NAME¶
systemd.network - Network configuration
SYNOPSIS¶
network.network
DESCRIPTION¶
A plain ini-style text file that encodes network configuration for
matching network interfaces, used by systemd-networkd(8). See
systemd.syntax(7) for a general description of the syntax.
The main network file must have the extension .network; other
extensions are ignored. Networks are applied to links whenever the links
appear.
Note that not all settings and configurations can be made with
.network files, and that it may be necessary to use systemd.link(5))
or systemd.netdev(5)) files in conjuction with .network files when
working with physical and virtual network devices respectively.
The .network files are read from the files located in the system
network directories /usr/lib/systemd/network and
/usr/local/lib/systemd/network [1], the volatile runtime network directory
/run/systemd/network and the local administration network directory
/etc/systemd/network. All configuration files are collectively sorted and
processed in alphanumeric order, regardless of the directories in which they
live. However, files with identical filenames replace each other. It is
recommended that each filename is prefixed with a number smaller than
"70" (e.g. 10-eth0.network). Otherwise, the default .network files
or those generated by systemd-network-generator.service(8) may take
precedence over user configured files. Files in /etc/ have the highest
priority, files in /run/ take precedence over files with the same name under
/usr/. This can be used to override a system-supplied configuration file
with a local file if needed. As a special case, an empty file (file size 0)
or symlink with the same name pointing to /dev/null disables the
configuration file entirely (it is "masked").
Along with the network file foo.network, a "drop-in"
directory foo.network.d/ may exist. All files with the suffix
".conf" from this directory will be merged in the alphanumeric
order and parsed after the main file itself has been parsed. This is useful
to alter or add configuration settings, without having to modify the main
configuration file. Each drop-in file must have appropriate section
headers.
In addition to /etc/systemd/network, drop-in ".d"
directories can be placed in /usr/lib/systemd/network or
/run/systemd/network directories. Drop-in files in /etc/ take precedence
over those in /run/ which in turn take precedence over those in /usr/lib/.
Drop-in files under any of these directories take precedence over the main
network file wherever located.
[MATCH] SECTION OPTIONS¶
The network file contains a [Match] section, which determines if a
given network file may be applied to a given interface; and a [Network]
section specifying how the interface should be configured. The first (in
alphanumeric order) of the network files that matches a given interface is
applied, all later files are ignored, even if they match as well.
Note that any network interfaces that have the
ID_NET_MANAGED_BY= udev property set will never be matched by any
.network files – unless the property's value is the string
"io.systemd.Network" – even if the [Match] section would
otherwise match. This may be used to exclude specific network interfaces
from systemd-networkd(8)'s management, while keeping the [Match]
section generic. The ID_NET_MANAGED_BY= property thus declares
intended ownership of the device, and permits ensuring that
concurrent network management implementations do not compete for management
of specific devices.
A network file is said to match a network interface if all matches
specified by the [Match] section are satisfied. When a network file does not
contain valid settings in [Match] section, then the file will match all
interfaces and systemd-networkd warns about that. Hint: to avoid the
warning and to make it clear that all interfaces shall be matched, add the
following:
The following keys are accepted:
MACAddress=
A whitespace-separated list of hardware addresses. The
acceptable formats are:
colon-delimited hexadecimal
Each field must be one byte. E.g.
"12:34:56:78:90:ab" or "AA:BB:CC:DD:EE:FF".
Added in version 250.
hyphen-delimited hexadecimal
Each field must be one byte. E.g.
"12-34-56-78-90-ab" or "AA-BB-CC-DD-EE-FF".
Added in version 250.
dot-delimited hexadecimal
Each field must be two bytes. E.g.
"1234.5678.90ab" or "AABB.CCDD.EEFF".
Added in version 250.
IPv4 address format
E.g. "127.0.0.1" or "192.168.0.1".
Added in version 250.
IPv6 address format
E.g. "2001:0db8:85a3::8a2e:0370:7334" or
"::1".
Added in version 250.
The total length of each MAC address must be 4 (for IPv4 tunnel),
6 (for Ethernet), 16 (for IPv6 tunnel), or 20 (for InfiniBand). This option
may appear more than once, in which case the lists are merged. If the empty
string is assigned to this option, the list of hardware addresses defined
prior to this is reset. Defaults to unset.
Added in version 211.
PermanentMACAddress=
A whitespace-separated list of hardware's permanent
addresses. While
MACAddress= matches the device's current MAC address,
this matches the device's permanent MAC address, which may be different from
the current one. Use full colon-, hyphen- or dot-delimited hexadecimal, or
IPv4 or IPv6 address format. This option may appear more than once, in which
case the lists are merged. If the empty string is assigned to this option, the
list of hardware addresses defined prior to this is reset. Defaults to unset.
Added in version 245.
Path=
A whitespace-separated list of shell-style globs matching
the persistent path, as exposed by the udev property
ID_PATH.
Added in version 211.
Driver=
A whitespace-separated list of shell-style globs matching
the driver currently bound to the device, as exposed by the udev property
ID_NET_DRIVER of its parent device, or if that is not set, the driver
as exposed by
ethtool -i of the device itself. If the list is prefixed
with a "!", the test is inverted.
Added in version 211.
Type=
A whitespace-separated list of shell-style globs matching
the device type, as exposed by
networkctl list. If the list is prefixed
with a "!", the test is inverted. Some valid values are
"ether", "loopback", "wlan", "wwan".
Valid types are named either from the udev "DEVTYPE" attribute, or
"ARPHRD_" macros in linux/if_arp.h, so this is not comprehensive.
Added in version 211.
Kind=
A whitespace-separated list of shell-style globs matching
the device kind, as exposed by
networkctl status
INTERFACE or
ip -d link show INTERFACE.
If the list is prefixed with a "!", the test is inverted. Some valid
values are "bond", "bridge", "gre",
"tun", "veth". Valid kinds are given by netlink's
"IFLA_INFO_KIND" attribute, so this is not comprehensive.
Added in version 251.
Property=
A whitespace-separated list of udev property names with
their values after equals sign ("="). If multiple properties are
specified, the test results are ANDed. If the list is prefixed with a
"!", the test is inverted. If a value contains white spaces, then
please quote whole key and value pair. If a value contains quotation, then
please escape the quotation with "\".
Example: if a .link file has the following:
Property=ID_MODEL_ID=9999 "ID_VENDOR_FROM_DATABASE=vendor name" "KEY=with \"quotation\""
then, the .link file matches only when an interface has all the
above three properties.
Added in version 243.
Name=
A whitespace-separated list of shell-style globs matching
the device name, as exposed by the udev property "INTERFACE", or
device's alternative names. If the list is prefixed with a "!", the
test is inverted.
Added in version 211.
WLANInterfaceType=
A whitespace-separated list of wireless network type.
Supported values are "ad-hoc", "station", "ap",
"ap-vlan", "wds", "monitor",
"mesh-point", "p2p-client", "p2p-go",
"p2p-device", "ocb", and "nan". If the list is
prefixed with a "!", the test is inverted.
Added in version 244.
SSID=
A whitespace-separated list of shell-style globs matching
the SSID of the currently connected wireless LAN. If the list is prefixed with
a "!", the test is inverted.
Added in version 244.
BSSID=
A whitespace-separated list of hardware address of the
currently connected wireless LAN. Use full colon-, hyphen- or dot-delimited
hexadecimal. See the example in
MACAddress=. This option may appear
more than once, in which case the lists are merged. If the empty string is
assigned to this option, the list is reset.
Added in version 244.
Host=
Matches against the hostname or machine ID of the host.
See
ConditionHost= in
systemd.unit(5) for details. When prefixed
with an exclamation mark ("!"), the result is negated. If an empty
string is assigned, the previously assigned value is cleared.
Added in version 211.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific implementation. See
ConditionVirtualization= in
systemd.unit(5) for details. When
prefixed with an exclamation mark ("!"), the result is negated. If
an empty string is assigned, the previously assigned value is cleared.
Added in version 211.
KernelCommandLine=
Checks whether a specific kernel command line option is
set. See
ConditionKernelCommandLine= in
systemd.unit(5) for
details. When prefixed with an exclamation mark ("!"), the result is
negated. If an empty string is assigned, the previously assigned value is
cleared.
Added in version 211.
KernelVersion=
Checks whether the kernel version (as reported by
uname -r) matches a certain expression. See
ConditionKernelVersion= in
systemd.unit(5) for details. When
prefixed with an exclamation mark ("!"), the result is negated. If
an empty string is assigned, the previously assigned value is cleared.
Added in version 237.
Credential=
Checks whether the specified credential was passed to the
systemd-udevd.service service. See
System and Service Credentials[2]
for details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the previously assigned
value is cleared.
Added in version 252.
Architecture=
Checks whether the system is running on a specific
architecture. See
ConditionArchitecture= in
systemd.unit(5) for
details. When prefixed with an exclamation mark ("!"), the result is
negated. If an empty string is assigned, the previously assigned value is
cleared.
Added in version 211.
Firmware=
Checks whether the system is running on a machine with
the specified firmware. See
ConditionFirmware= in
systemd.unit(5) for details. When prefixed with an exclamation mark
("!"), the result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 249.
[LINK] SECTION OPTIONS¶
The [Link] section accepts the following keys:
MACAddress=
The hardware address to set for the device.
Added in version 218.
MTUBytes=
The maximum transmission unit in bytes to set for the
device. The usual suffixes K, M, G, are supported and are understood to the
base of 1024.
Note that if IPv6 is enabled on the interface, and the MTU is
chosen below 1280 (the minimum MTU for IPv6) it will automatically be
increased to this value.
Added in version 218.
ARP=
Takes a boolean. If set to true, the IPv4 ARP (low-level
Address Resolution Protocol) and IPv6 NDP (Neighbor Discovery Protocol) for
this interface are enabled. When unset, the kernel's default will be used.
For example, disabling ARP is useful when creating multiple
MACVLAN or VLAN virtual interfaces atop a single lower-level physical
interface, which will then only serve as a link/"bridge" device
aggregating traffic to the same physical link and not participate in the
network otherwise. Defaults to unset.
Added in version 232.
Multicast=
Takes a boolean. If set to true, the multicast flag on
the device is enabled. Defaults to unset.
Added in version 239.
AllMulticast=
Takes a boolean. If set to true, the driver retrieves all
multicast packets from the network. This happens when multicast routing is
enabled. Defaults to unset.
Added in version 239.
Promiscuous=
Takes a boolean. If set to true, promiscuous mode of the
interface is enabled. Defaults to unset.
If this is set to false for the underlying link of a
"passthru" mode MACVLAN/MACVTAP, the virtual interface will be
created with the "nopromisc" flag set.
Added in version 248.
Unmanaged=
Takes a boolean. When "yes", no attempts are
made to bring up or configure matching links, equivalent to when there are no
matching network files. Defaults to "no".
This is useful for preventing later matching network files from
interfering with certain interfaces that are fully controlled by other
applications.
Added in version 233.
Group=
Link groups are similar to port ranges found in managed
switches. When network interfaces are added to a numbered group, operations on
all the interfaces from that group can be performed at once. Takes an unsigned
integer in the range 0...2147483647. Defaults to unset.
Added in version 246.
RequiredForOnline=
Takes a boolean, a minimum operational state (e.g.,
"carrier"), or a range of operational state separated with a colon
(e.g., "degraded:routable"). Please see
networkctl(1) for
possible operational states. When "yes", the network is deemed
required when determining whether the system is online (including when running
systemd-networkd-wait-online). When "no", the network is
ignored when determining the online state. When a minimum operational state
and an optional maximum operational state are set,
systemd-networkd-wait-online deems that the interface is online when
the operational state is in the specified range.
Defaults to "yes" when ActivationPolicy= is not
set, or set to "up", "always-up", or "bound".
Defaults to "no" when ActivationPolicy= is set to
"manual" or "down". This is forced to "no"
when ActivationPolicy= is set to "always-down".
The network will be brought up normally (as configured by
ActivationPolicy=), but in the event that there is no address being
assigned by DHCP or the cable is not plugged in, the link will simply remain
offline and be skipped automatically by systemd-networkd-wait-online
if "RequiredForOnline=no".
The boolean value "yes" is translated as follows;
CAN devices
"carrier",
Added in version 256.
Master devices, e.g. bond or bridge
"degraded-carrier" with
RequiredFamilyForOnline=any,
Added in version 256.
Bonding port interfaces
"enslaved",
Added in version 256.
Other interfaces
"degraded".
Added in version 236.
This setting can be overridden by the command line option for
systemd-networkd-wait-online. See
systemd-networkd-wait-online.service(8) for more details.
Added in version 236.
RequiredFamilyForOnline=
Takes an address family. When specified, an IP address in
the given family is deemed required when determining whether the link is
online (including when running
systemd-networkd-wait-online). Takes one
of "ipv4", "ipv6", "both", or "any".
Defaults to "no". Note that this option has no effect if
"RequiredForOnline=no".
Added in version 249.
ActivationPolicy=
Specifies the policy for
systemd-networkd managing
the link administrative state. Specifically, this controls how
systemd-networkd changes the network device's "IFF_UP" flag,
which is sometimes controlled by system administrators by running e.g.,
ip
link set dev eth0 up or
ip link set dev eth0 down, and can also be
changed with
networkctl up eth0 or
networkctl down eth0.
Takes one of "up", "always-up",
"manual", "always-down", "down", or
"bound". When "manual", systemd-networkd will not
change the link's admin state automatically; the system administrator must
bring the interface up or down manually, as desired. When "up"
(the default) or "always-up", or "down" or
"always-down", systemd-networkd will set the link up or
down, respectively, when the interface is (re)configured. When
"always-up" or "always-down", systemd-networkd
will set the link up or down, respectively, any time systemd-networkd
detects a change in the administrative state. When BindCarrier= is
also set, this is automatically set to "bound" and any other value
is ignored.
When the policy is set to "down" or "manual",
the default value of RequiredForOnline= is "no". When the
policy is set to "always-down", the value of
RequiredForOnline= forced to "no".
The administrative state is not the same as the carrier state, so
using "always-up" does not mean the link will never lose carrier.
The link carrier depends on both the administrative state as well as the
network device's physical connection. However, to avoid reconfiguration
failures, when using "always-up", IgnoreCarrierLoss= is
forced to true.
Added in version 248.
[SR-IOV] SECTION OPTIONS¶
SR-IOV provides the ability to partition a single physical PCI
resource into virtual PCI functions which can then be e.g. injected into a
VM. In the case of network VFs, SR-IOV reduces latency and CPU utilisation
for north-south network traffic (that is, traffic with endpoints outside the
host machine), by allowing traffic to bypass the host machine’s
network stack.
The presence of an [SR-IOV] section in a .link file will cause the
creation and configuration of the specified virtual function. Within a
.network file, the specified virtual function will be configured, but must
already exist. Specify several [SR-IOV] sections to configure several
SR-IOVs.
The [SR-IOV] section accepts the following keys.
VirtualFunction=
Specifies a Virtual Function (VF), lightweight PCIe
function designed solely to move data in and out. Takes an integer in the
range 0...2147483646. This option is compulsory.
Added in version 251.
VLANId=
Specifies VLAN ID of the virtual function. Takes an
integer in the range 1...4095.
Added in version 251.
QualityOfService=
Specifies quality of service of the virtual function.
Takes an integer in the range 1...4294967294.
Added in version 251.
VLANProtocol=
Specifies VLAN protocol of the virtual function. Takes
"802.1Q" or "802.1ad".
Added in version 251.
MACSpoofCheck=
Takes a boolean. Controls the MAC spoof checking. When
unset, the kernel's default will be used.
Added in version 251.
QueryReceiveSideScaling=
Takes a boolean. Toggle the ability of querying the
receive side scaling (RSS) configuration of the virtual function (VF). The VF
RSS information like RSS hash key may be considered sensitive on some devices
where this information is shared between VF and the physical function (PF).
When unset, the kernel's default will be used.
Added in version 251.
Trust=
Takes a boolean. Allows one to set trust mode of the
virtual function (VF). When set, VF users can set a specific feature which may
impact security and/or performance. When unset, the kernel's default will be
used.
Added in version 251.
LinkState=
Allows one to set the link state of the virtual function
(VF). Takes a boolean or a special value "auto". Setting to
"auto" means a reflection of the physical function (PF) link state,
"yes" lets the VF to communicate with other VFs on this host even if
the PF link state is down, "no" causes the hardware to drop any
packets sent by the VF. When unset, the kernel's default will be used.
Added in version 251.
MACAddress=
Specifies the MAC address for the virtual function.
Added in version 251.
[NETWORK] SECTION OPTIONS¶
The [Network] section accepts the following keys:
Description=
A description of the device. This is only used for
presentation purposes.
Added in version 211.
DHCP=
Enables DHCPv4 and/or DHCPv6 client support. Accepts
"yes", "no", "ipv4", or "ipv6".
Defaults to "no".
Note that DHCPv6 will by default be triggered by Router
Advertisements, if reception is enabled, regardless of this parameter. By
explicitly enabling DHCPv6 support here, the DHCPv6 client will be started
in the mode specified by the WithoutRA= setting in the [DHCPv6]
section, regardless of the presence of routers on the link, or what flags
the routers pass. See IPv6AcceptRA=.
Furthermore, note that by default the domain name specified
through DHCP is not used for name resolution. See option UseDomains=
below.
See the [DHCPv4] or [DHCPv6] sections below for further
configuration options for the DHCP client support.
Added in version 211.
DHCPServer=
Takes a boolean. If set to "yes", DHCPv4 server
will be started. Defaults to "no". Further settings for the DHCP
server may be set in the [DHCPServer] section described below.
Even if this is enabled, the DHCP server will not be started
automatically and wait for the persistent storage being ready to load/save
leases in the storage, unless RelayTarget= or PersistLeases=no
are specified in the [DHCPServer] section. It will be started after
systemd-networkd-persistent-storage.service is started, which calls
networkctl persistent-storage yes. See networkctl(1) for more
details.
Added in version 215.
LinkLocalAddressing=
Enables link-local address autoconfiguration. Accepts a
boolean,
ipv4, and
ipv6. An IPv6 link-local address is
configured when
yes or
ipv6. An IPv4 link-local address is
configured when
yes or
ipv4 and when DHCPv4 autoconfiguration
has been unsuccessful for some time. (IPv4 link-local address
autoconfiguration will usually happen in parallel with repeated attempts to
acquire a DHCPv4 lease).
Defaults to no when KeepMaster= or Bridge= is
set or when the specified MACVLAN=/MACVTAP= has
Mode=passthru, or ipv6 otherwise.
Added in version 219.
IPv6LinkLocalAddressGenerationMode=
Specifies how IPv6 link-local address is generated. Takes
one of "eui64", "none", "stable-privacy" and
"random". When unset, "stable-privacy" is used if
IPv6StableSecretAddress= is specified, and if not, "eui64" is
used. Note that if
LinkLocalAddressing= is "no" or
"ipv4", then
IPv6LinkLocalAddressGenerationMode= will be
ignored. Also, even if
LinkLocalAddressing= is "yes" or
"ipv6", setting
IPv6LinkLocalAddressGenerationMode=none
disables to configure an IPv6 link-local address.
Added in version 246.
IPv6StableSecretAddress=
Takes an IPv6 address. The specified address will be used
as a stable secret for generating IPv6 link-local address. If this setting is
specified, and
IPv6LinkLocalAddressGenerationMode= is unset, then
IPv6LinkLocalAddressGenerationMode=stable-privacy is implied. If this
setting is not specified, and "stable-privacy" is set to
IPv6LinkLocalAddressGenerationMode=, then a stable secret address will
be generated from the local machine ID and the interface name.
Added in version 249.
IPv4LLStartAddress=
Specifies the first IPv4 link-local address to try. Takes
an IPv4 address for example 169.254.1.2, from the link-local address range:
169.254.0.0/16 except for 169.254.0.0/24 and 169.254.255.0/24. This setting
may be useful if the device should always have the same address as long as
there is no address conflict. When unset, a random address will be
automatically selected. Defaults to unset.
Added in version 252.
IPv4LLRoute=
Takes a boolean. If set to true, sets up the route needed
for non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults to false.
Added in version 216.
DefaultRouteOnDevice=
Takes a boolean. If set to true, sets up the IPv4 default
route bound to the interface. Defaults to false. This is useful when creating
routes on point-to-point interfaces. This is equivalent to e.g. the following,
ip route add default dev veth99
or,
Currently, there are no way to specify e.g., the table for the
route configured by this setting. To configure the default route with such
an additional property, please use the following instead:
[Route]
Gateway=0.0.0.0
Table=1234
If you'd like to create an IPv6 default route bound to the
interface, please use the following:
[Route]
Gateway=::
Table=1234
Added in version 243.
LLMNR=
Takes a boolean or "resolve". When true,
enables
Link-Local Multicast Name Resolution[3] on the link. When set
to "resolve", only resolution is enabled, but not host registration
and announcement. Defaults to true. This setting is read by
systemd-resolved.service(8).
Added in version 216.
MulticastDNS=
Takes a boolean or "resolve". When true,
enables
Multicast DNS[4] support on the link. When set to
"resolve", only resolution is enabled, but not host or service
registration and announcement. Defaults to false. This setting is read by
systemd-resolved.service(8).
Added in version 229.
DNSOverTLS=
Takes a boolean or "opportunistic". When true,
enables
DNS-over-TLS[5] support on the link. When set to
"opportunistic", compatibility with non-DNS-over-TLS servers is
increased, by automatically turning off DNS-over-TLS servers in this case.
This option defines a per-interface setting for
resolved.conf(5)'s
global
DNSOverTLS= option. Defaults to unset, and the global setting
will be used. This setting is read by
systemd-resolved.service(8).
Added in version 239.
DNSSEC=
Takes a boolean or "allow-downgrade". When
true, enables
DNSSEC[6] DNS validation support on the link. When set to
"allow-downgrade", compatibility with non-DNSSEC capable networks is
increased, by automatically turning off DNSSEC in this case. This option
defines a per-interface setting for
resolved.conf(5)'s global
DNSSEC= option. Defaults to unset, and the global setting will be used.
This setting is read by
systemd-resolved.service(8).
Added in version 229.
DNSSECNegativeTrustAnchors=
A space-separated list of DNSSEC negative trust anchor
domains. If specified and DNSSEC is enabled, look-ups done via the interface's
DNS server will be subject to the list of negative trust anchors, and not
require authentication for the specified domains, or anything below it. Use
this to disable DNSSEC authentication for specific private domains, that
cannot be proven valid using the Internet DNS hierarchy. Defaults to the empty
list. This setting is read by
systemd-resolved.service(8).
Added in version 229.
LLDP=
Controls support for Ethernet LLDP packet reception. LLDP
is a link-layer protocol commonly implemented on professional routers and
bridges which announces which physical port a system is connected to, as well
as other related data. Accepts a boolean or the special value
"routers-only". When true, incoming LLDP packets are accepted and a
database of all LLDP neighbors maintained. If "routers-only" is set
only LLDP data of various types of routers is collected and LLDP data about
other types of devices ignored (such as stations, telephones and others). If
false, LLDP reception is disabled. Defaults to "routers-only". Use
networkctl(1) to query the collected neighbor data. LLDP is only
available on Ethernet links. See
EmitLLDP= below for enabling LLDP
packet emission from the local system.
Added in version 219.
EmitLLDP=
Controls support for Ethernet LLDP packet emission.
Accepts a boolean parameter or the special values "nearest-bridge",
"non-tpmr-bridge" and "customer-bridge". Defaults to
false, which turns off LLDP packet emission. If not false, a short LLDP packet
with information about the local system is sent out in regular intervals on
the link. The LLDP packet will contain information about the local hostname,
the local machine ID (as stored in
machine-id(5)) and the local
interface name, as well as the pretty hostname of the system (as set in
machine-info(5)). LLDP emission is only available on Ethernet links.
Note that this setting passes data suitable for identification of host to the
network and should thus not be enabled on untrusted networks, where such
identification data should not be made available. Use this option to permit
other systems to identify on which interfaces they are connected to this
system. The three special values control propagation of the LLDP packets. The
"nearest-bridge" setting permits propagation only to the nearest
connected bridge, "non-tpmr-bridge" permits propagation across
Two-Port MAC Relays, but not any other bridges, and
"customer-bridge" permits propagation until a customer bridge is
reached. For details about these concepts, see
IEEE 802.1AB-2016[7].
Note that configuring this setting to true is equivalent to
"nearest-bridge", the recommended and most restricted level of
propagation. See
LLDP= above for an option to enable LLDP reception.
Added in version 230.
BindCarrier=
A link name or a list of link names. When set, controls
the behavior of the current link. When all links in the list are in an
operational down state, the current link is brought down. When at least one
link has carrier, the current interface is brought up.
This forces ActivationPolicy= to be set to
"bound".
Added in version 220.
Address=
A static IPv4 or IPv6 address and its prefix length,
separated by a "/" character. Specify this key more than once to
configure several addresses. The format of the address must be as described in
inet_pton(3). This is a short-hand for an [Address] section only
containing an Address key (see below). This option may be specified more than
once.
If the specified address is "0.0.0.0" (for IPv4) or
"::" (for IPv6), a new address range of the requested size is
automatically allocated from a system-wide pool of unused ranges. Note that
the prefix length must be equal or larger than 8 for IPv4, and 64 for IPv6.
The allocated range is checked against all current network interfaces and
all known network configuration files to avoid address range conflicts. The
default system-wide pool consists of 192.168.0.0/16, 172.16.0.0/12 and
10.0.0.0/8 for IPv4, and fd00::/8 for IPv6. This functionality is useful to
manage a large number of dynamically created network interfaces with the
same network configuration and automatic address range assignment.
If an IPv4 link-local address (169.254.0.0/16) is specified, IPv4
Address Conflict Detection (RFC 5227[8]) is enabled for the address.
To assign an IPv4 link-local address without IPv4 Address Conflict
Detection, please use [Address] section to configure the address and disable
DuplicateAddressDetection=.
[Address]
Address=169.254.10.1/24
DuplicateAddressDetection=none
If an empty string is specified, then the all previous assignments
in both [Network] and [Address] sections are cleared.
Added in version 211.
Gateway=
The gateway address, which must be in the format
described in
inet_pton(3). This is a short-hand for a [Route] section
only containing a
Gateway= key. This option may be specified more than
once.
Added in version 211.
DNS=
A DNS server address, which must be in the format
described in
inet_pton(3). This option may be specified more than once.
Each address can optionally take a port number separated with ":", a
network interface name or index separated with "%", and a Server
Name Indication (SNI) separated with "#". When IPv6 address is
specified with a port number, then the address must be in the square brackets.
That is, the acceptable full formats are
"111.222.333.444:9953%ifname#example.com" for IPv4 and
"[1111:2222::3333]:9953%ifname#example.com" for IPv6. If an empty
string is assigned, then the all previous assignments are cleared. This
setting is read by
systemd-resolved.service(8).
Added in version 211.
UseDomains=
Specifies the protocol-independent default value for the
same settings in [IPv6AcceptRA], [DHCPv4], and [DHCPv6] sections below. Takes
a boolean, or the special value
route. See also the same setting in
[DHCPv4] below. Defaults to unset.
Added in version 256.
Domains=
A whitespace-separated list of domains which should be
resolved using the DNS servers on this link. Each item in the list should be a
domain name, optionally prefixed with a tilde ("~"). The domains
with the prefix are called "routing-only domains". The domains
without the prefix are called "search domains" and are first used as
search suffixes for extending single-label hostnames (hostnames containing no
dots) to become fully qualified domain names (FQDNs). If a single-label
hostname is resolved on this interface, each of the specified search domains
are appended to it in turn, converting it into a fully qualified domain name,
until one of them may be successfully resolved.
Both "search" and "routing-only" domains are
used for routing of DNS queries: look-ups for hostnames ending in those
domains (hence also single label names, if any "search domains"
are listed), are routed to the DNS servers configured for this interface.
The domain routing logic is particularly useful on multi-homed hosts with
DNS servers serving particular private DNS zones on each interface.
The "routing-only" domain "~." (the tilde
indicating definition of a routing domain, the dot referring to the DNS root
domain which is the implied suffix of all valid DNS names) has special
effect. It causes all DNS traffic which does not match another configured
domain routing entry to be routed to DNS servers specified for this
interface. This setting is useful to prefer a certain set of DNS servers if
a link on which they are connected is available.
This setting is read by systemd-resolved.service(8).
"Search domains" correspond to the domain and search
entries in resolv.conf(5). Domain name routing has no equivalent in
the traditional glibc API, which has no concept of domain name servers
limited to a specific link.
Added in version 216.
DNSDefaultRoute=
Takes a boolean argument. If true, this link's configured
DNS servers are used for resolving domain names that do not match any link's
configured
Domains= setting. If false, this link's configured DNS
servers are never used for such domains, and are exclusively used for
resolving names that match at least one of the domains configured on this
link. If not specified, defaults to an automatic mode: queries not matching
any link's configured domains will be routed to this link if it has no
routing-only domains configured.
Added in version 240.
NTP=
An NTP server address (either an IP address, or a
hostname). This option may be specified more than once. This setting is read
by
systemd-timesyncd.service(8).
Added in version 216.
IPv4Forwarding=
Configures IPv4 packet forwarding for the interface.
Takes a boolean value. This controls the
net.ipv4.conf.
INTERFACE.forwarding sysctl option of the network
interface. See
IP Sysctl[9] for more details about the sysctl option.
Defaults to true if
IPMasquerade= is enabled for IPv4, otherwise the
value specified to the same setting in
networkd.conf(5) will be used.
If none of them are specified, the sysctl option will not be changed.
To control the global setting, use the same setting in
networkd.conf(5).
Added in version 256.
IPv6Forwarding=
Configures interface-specific host/router behaviour.
Takes a boolean value. This controls the
net.ipv6.conf.
INTERFACE.forwarding sysctl option of the network
interface. See
IP Sysctl[9] for more details about the sysctl option.
Defaults to true if
IPMasquerade= is enabled for IPv6 or
IPv6SendRA= is enabled, otherwise the value specified to the same
setting in
networkd.conf(5) will be used. If none of them are
specified, the sysctl option will not be changed.
To control the global setting, use the same setting in
networkd.conf(5).
Note, unlike IPv4Forwarding=, enabling per-interface
IPv6Forwarding= on two or more interfaces DOES NOT make IPv6
packets forwarded within the interfaces. This setting just controls the
per-interface sysctl value, and the sysctl value is not directly correlated
to whether packets are forwarded. To ensure IPv6 packets forwarded, the
global setting in networkd.conf(5) needs to be enabled.
Added in version 256.
IPMasquerade=
Configures IP masquerading for the network interface. If
enabled, packets forwarded from the network interface will be appear as coming
from the local host. Typically, this should be enabled on the downstream
interface of routers. Takes one of "ipv4", "ipv6",
"both", or "no". Defaults to "no". Note that any
positive boolean values such as "yes" or "true" are now
deprecated. Please use one of the values above. Specifying "ipv4" or
"both" implies
IPv4Forwarding= settings in both .network file
for this interface and the global
networkd.conf(5) unless they are
explicitly specified. Similarly for
IPv6Forwarding= when
"ipv6" or "both" is specified. See
IPv4Forwarding=/
IPv6Forwarding= in the above for the per-link
settings, and
networkd.conf(5) for the global settings.
Added in version 219.
IPv6PrivacyExtensions=
Configures use of stateless temporary addresses that
change over time (see
RFC 4941[10], Privacy Extensions for Stateless
Address Autoconfiguration in IPv6). Takes a boolean or the special values
"prefer-public" and "kernel". When true, enables the
privacy extensions and prefers temporary addresses over public addresses. When
"prefer-public", enables the privacy extensions, but prefers public
addresses over temporary addresses. When false, the privacy extensions remain
disabled. When "kernel", the kernel's default setting will be left
in place. When unspecified, the value specified in the same setting in
networkd.conf(5), which defaults to "no", will be used.
Added in version 222.
IPv6AcceptRA=
Takes a boolean. Controls IPv6 Router Advertisement (RA)
reception support for the interface. If true, RAs are accepted; if false, RAs
are ignored. When RAs are accepted, they may trigger the start of the DHCPv6
client if the relevant flags are set in the RA data, or if no routers are
found on the link. Defaults to false for bridge devices, when
IPv6Forwarding=,
IPv6SendRA=, or
KeepMaster= is enabled.
Otherwise, enabled by default. Cannot be enabled on devices aggregated in a
bond device or when link-local addressing is disabled.
Further settings for the IPv6 RA support may be configured in the
[IPv6AcceptRA] section, see below.
Also see IP Sysctl[9] in the kernel documentation regarding
"accept_ra", but note that systemd's setting of 1 (i.e.
true) corresponds to kernel's setting of 2.
Note that kernel's implementation of the IPv6 RA protocol is
always disabled, regardless of this setting. If this option is enabled, a
userspace implementation of the IPv6 RA protocol is used, and the kernel's
own implementation remains disabled, since systemd-networkd needs to
know all details supplied in the advertisements, and these are not available
from the kernel if the kernel's own implementation is used.
Added in version 231.
IPv6DuplicateAddressDetection=
Configures the amount of IPv6 Duplicate Address Detection
(DAD) probes to send. When unset, the kernel's default will be used.
Added in version 228.
IPv6HopLimit=
Configures IPv6 Hop Limit. Takes an integer in the range
1...255. For each router that forwards the packet, the hop limit is
decremented by 1. When the hop limit field reaches zero, the packet is
discarded. When unset, the kernel's default will be used.
Added in version 228.
IPv6RetransmissionTimeSec=
Configures IPv6 Retransmission Time. The time between
retransmitted Neighbor Solicitation messages. Used by address resolution and
the Neighbor Unreachability Detection algorithm. A value of zero is ignored
and the kernel's current value will be used. Defaults to unset, and the
kernel's current value will be used.
Added in version 256.
IPv4ReversePathFilter=
Configure IPv4 Reverse Path Filtering. If enabled, when
an IPv4 packet is received, the machine will first check whether the
source of the packet would be routed through the interface it came in.
If there is no route to the source on that interface, the machine will drop
the packet. Takes one of "no", "strict", or
"loose". When "no", no source validation will be done.
When "strict", each incoming packet is tested against the FIB and if
the incoming interface is not the best reverse path, the packet check will
fail. By default, failed packets are discarded. When "loose", each
incoming packet's source address is tested against the FIB. The packet is
dropped only if the source address is not reachable via any interface on that
router. See
RFC 3704[11]. When unset, the kernel's default will be
used.
Added in version 255.
MulticastIGMPVersion=
Configures IPv4 Multicast IGMP Version to be used, and
controls the value of
/proc/sys/net/ipv4/conf/
INTERFACE/force_igmp_version. Takes one of
"no", "v1", "v2", or "v3". When
"no", no enforcement of an IGMP version is applied. IGMPv1/v2
fallbacks are allowed, and
systemd-networkd will return to IGMPv3 mode
after all IGMPv1/v2 Querier Present timers have expired. When "v1",
use of IGMP version 1 is enforced. An IGMPv1 report will be returned even if
IGMPv2/v3 queries are received. When "v2", use of IGMP version 2 is
enforced. An IGMPv2 report will be returned if an IGMPv2/v3 query is received.
systemd-networkd will fall back to IGMPv1 if an IGMPv1 query is
received. When "v3", use of IGMP version 3 is enforced, and the
response is the same as with "no". Defaults to unset — the
sysctl is not set.
Added in version 257.
IPv4AcceptLocal=
Takes a boolean. Accept packets with local source
addresses. In combination with suitable routing, this can be used to direct
packets between two local interfaces over the wire and have them accepted
properly. When unset, the kernel's default will be used.
Added in version 246.
IPv4RouteLocalnet=
Takes a boolean. When true, the kernel does not consider
loopback addresses as martian source or destination while routing. This
enables the use of 127.0.0.0/8 for local routing purposes. When unset, the
kernel's default will be used.
Added in version 248.
IPv4ProxyARP=
Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP
is the technique in which one host, usually a router, answers ARP requests
intended for another machine. By "faking" its identity, the router
accepts responsibility for routing packets to the "real"
destination. See
RFC 1027[11]. When unset, the kernel's default will be
used.
Added in version 233.
IPv4ProxyARPPrivateVLAN=
Takes a boolean. Configures proxy ARP private VLAN for
IPv4, also known as VLAN aggregation, private VLAN, source-port filtering,
port-isolation, or MAC-forced forwarding.
This variant of the ARP proxy technique will allow the ARP proxy
to reply back to the same interface.
See RFC 3069[12]. When unset, the kernel's default will be
used.
Added in version 256.
IPv6ProxyNDP=
Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP
(Neighbor Discovery Protocol) is a technique for IPv6 to allow routing of
addresses to a different destination when peers expect them to be present on a
certain physical link. In this case, a router answers Neighbour Advertisement
messages intended for another machine by offering its own MAC address as
destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will
only send Neighbour Advertisement messages for addresses in the IPv6 neighbor
proxy table, which can also be shown by
ip -6 neighbour show proxy.
systemd-networkd will control the per-interface `proxy_ndp` switch for
each configured interface depending on this option. When unset, the kernel's
default will be used.
Added in version 234.
IPv6ProxyNDPAddress=
An IPv6 address, for which Neighbour Advertisement
messages will be proxied. This option may be specified more than once.
systemd-networkd will add the
IPv6ProxyNDPAddress= entries to
the kernel's IPv6 neighbor proxy table. This setting implies
IPv6ProxyNDP=yes but has no effect if
IPv6ProxyNDP= has been set
to false. When unset, the kernel's default will be used.
Added in version 233.
IPv6SendRA=
Whether to enable or disable Router Advertisement sending
on a link. Takes a boolean value. When enabled, prefixes configured in
[IPv6Prefix] sections and routes configured in the [IPv6RoutePrefix] sections
are distributed as defined in the [IPv6SendRA] section. If
DHCPPrefixDelegation= is enabled, then the delegated prefixes are also
distributed. See
DHCPPrefixDelegation= setting and the [IPv6SendRA],
[IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more
configuration options.
If enabled, IPv6Forwarding= on this interface is also
enabled, unless the setting is explicitly specified. See
IPv6Forwarding= in the above for more details.
Added in version 247.
DHCPPrefixDelegation=
Takes a boolean value. When enabled, requests subnet
prefixes on another link via the DHCPv6 protocol or via the 6RD option in the
DHCPv4 protocol. An address within each delegated prefix will be assigned, and
the prefixes will be announced through IPv6 Router Advertisement if
IPv6SendRA= is enabled. This behaviour can be configured in the
[DHCPPrefixDelegation] section. Defaults to disabled.
Added in version 250.
IPv6MTUBytes=
Configures IPv6 maximum transmission unit (MTU). An
integer greater than or equal to 1280 bytes. When unset, the kernel's default
will be used.
Added in version 239.
KeepMaster=
Takes a boolean value. When enabled, the current master
interface index will not be changed, and
BatmanAdvanced=,
Bond=,
Bridge=, and
VRF= settings are ignored. This may be useful when
a netdev with a master interface is created by another program, e.g.
systemd-nspawn(1). Defaults to false.
Added in version 250.
BatmanAdvanced=, Bond=, Bridge=,
VRF=
The name of the B.A.T.M.A.N. Advanced, bond, bridge, or
VRF interface to add the link to. See
systemd.netdev(5).
Added in version 211.
IPoIB=, IPVLAN=, IPVTAP=, MACsec=,
MACVLAN=, MACVTAP=, Tunnel=, VLAN=,
VXLAN=, Xfrm=
The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN,
MACVTAP, tunnel, VLAN, VXLAN, or Xfrm to be created on the link. See
systemd.netdev(5). This option may be specified more than once.
Added in version 211.
ActiveSlave=
Takes a boolean. Specifies the new active slave. The
"ActiveSlave=" option is only valid for following modes:
"active-backup", "balance-alb", and
"balance-tlb". Defaults to false.
Added in version 235.
PrimarySlave=
Takes a boolean. Specifies which slave is the primary
device. The specified device will always be the active slave while it is
available. Only when the primary is off-line will alternate devices be used.
This is useful when one slave is preferred over another, e.g. when one slave
has higher throughput than another. The "PrimarySlave=" option is
only valid for following modes: "active-backup",
"balance-alb", and "balance-tlb". Defaults to false.
Added in version 235.
ConfigureWithoutCarrier=
Takes a boolean. Allows
systemd-networkd to
configure a specific link even if it has no carrier. Defaults to false. If
enabled, and the
IgnoreCarrierLoss= setting is not explicitly set, then
it is enabled as well.
With this enabled, to make the interface enter the
"configured" state, which is required to make
systemd-networkd-wait-online work properly for the interface, all
dynamic address configuration mechanisms like DHCP= and
IPv6AcceptRA= (which is enabled by default in most cases) need to be
disabled. Also, DuplicateAddressDetection= (which is enabled by
default for IPv4 link-local addresses and all IPv6 addresses) needs to be
disabled for all static address configurations. Otherwise, without carrier,
the interface will be stuck in the "configuring" state, and
systemd-networkd-wait-online for the interface will timeout. Also, it
is recommended to set RequiredForOnline=no-carrier to make
systemd-networkd-wait-online work for the interface.
Added in version 235.
IgnoreCarrierLoss=
Takes a boolean or a timespan. When true,
systemd-networkd retains both the static and dynamic configuration of
the interface even if its carrier is lost. When false,
systemd-networkd
drops both the static and dynamic configuration of the interface. When a
timespan is specified,
systemd-networkd waits for the specified
timespan, and ignores the carrier loss if the link regain its carrier within
the timespan. Setting 0 seconds is equivalent to "no", and
"infinite" is equivalent to "yes".
Setting a finite timespan may be useful when e.g. in the following
cases:
•A wireless interface connecting to a network
which has multiple access points with the same SSID.
•Enslaving a wireless interface to a bond
interface, which may disconnect from the connected access point and causes its
carrier to be lost.
•The driver of the interface resets when the MTU
is changed.
When Bond= is specified to a wireless interface, defaults
to 3 seconds. When the DHCPv4 client is enabled and UseMTU= in the
[DHCPv4] section enabled, defaults to 5 seconds. Otherwise, defaults to the
value specified with ConfigureWithoutCarrier=. When
ActivationPolicy= is set to "always-up", this is forced to
"yes", and ignored any user specified values.
Added in version 242.
KeepConfiguration=
Takes a boolean or one of "static",
"dynamic-on-stop", and "dynamic". When "static",
systemd-networkd will not drop statically configured addresses and
routes on starting up process. When "dynamic-on-stop", the
dynamically configurad addresses and routes, such as DHCPv4, DHCPv6, SLAAC,
and IPv4 link-local address, will not be dropped when
systemd-networkd
is being stopped. When "dynamic", the dynamically configured
addresses and routes will never be dropped, and the lifetime of DHCPv4 leases
will be ignored. This is contrary to the DHCP specification, but may be the
best choice if, e.g., the root filesystem relies on this connection. The
setting "dynamic" implies "dynamic-on-stop", and
"yes" implies "dynamic" and "static". Defaults
to "dynamic-on-stop" when
systemd-networkd is running in
initrd, "yes" when the root filesystem is a network filesystem, and
"no" otherwise.
Added in version 257.
[ADDRESS] SECTION OPTIONS¶
An [Address] section accepts the following keys. Specify several
[Address] sections to configure several addresses.
Address=
As in the [Network] section. This setting is mandatory.
Each [Address] section can contain one
Address= setting.
Added in version 211.
Peer=
The peer address in a point-to-point connection. Accepts
the same format as the
Address= setting.
Added in version 216.
Broadcast=
Takes an IPv4 address or boolean value. The address must
be in the format described in
inet_pton(3). If set to true, then the
IPv4 broadcast address will be derived from the
Address= setting. If
set to false, then the broadcast address will not be set. Defaults to true,
except for wireguard interfaces, where it default to false.
Added in version 211.
Label=
Specifies the label for the IPv4 address. The label must
be a 7-bit ASCII string with a length of 1...15 characters. Defaults to unset.
Added in version 211.
PreferredLifetime=
Allows the default "preferred lifetime" of the
address to be overridden. Only three settings are accepted:
"forever", "infinity", which is the default and means that
the address never expires, and "0", which means that the address is
considered immediately "expired" and will not be used, unless
explicitly requested. A setting of
PreferredLifetime=0 is useful for
addresses which are added to be used only by a specific application, which is
then configured to use them explicitly.
Added in version 230.
Scope=
The scope of the address, which can be "global"
(valid everywhere on the network, even through a gateway), "link"
(only valid on this device, will not traverse a gateway) or "host"
(only valid within the device itself, e.g. 127.0.0.1) or an integer in the
range 0...255. Defaults to "global". IPv4 only - IPv6 scope is
automatically assigned by the kernel and cannot be set manually.
Added in version 235.
RouteMetric=
The metric of the prefix route, which is pointing to the
subnet of the configured IP address, taking the configured prefix length into
account. Takes an unsigned integer in the range 0...4294967295. When unset or
set to 0, the kernel's default value is used. This setting will be ignored
when
AddPrefixRoute= is false.
Added in version 246.
HomeAddress=
Takes a boolean. Designates this address the "home
address" as defined in
RFC 6275[13]. Supported only on IPv6.
Defaults to false.
Added in version 232.
DuplicateAddressDetection=
Takes one of "ipv4", "ipv6",
"both", or "none". When "ipv4", performs IPv4
Address Conflict Detection. See
RFC 5227[8]. When "ipv6",
performs IPv6 Duplicate Address Detection. See
RFC 4862[14]. Defaults
to "ipv4" for IPv4 link-local addresses (169.254.0.0/16),
"ipv6" for IPv6 addresses, and "none" otherwise.
Added in version 232.
ManageTemporaryAddress=
Takes a boolean. If true the kernel manage temporary
addresses created from this one as template on behalf of Privacy Extensions
RFC 3041[15]. For this to become active, the use_tempaddr sysctl
setting has to be set to a value greater than zero. The given address needs to
have a prefix length of 64. This flag allows using privacy extensions in a
manually configured network, just like if stateless auto-configuration was
active. Defaults to false.
Added in version 232.
AddPrefixRoute=
Takes a boolean. When true, the prefix route for the
address is automatically added. Defaults to true.
Added in version 245.
AutoJoin=
Takes a boolean. Joining multicast group on ethernet
level via
ip maddr command would not work if we have an Ethernet switch
that does IGMP snooping since the switch would not replicate multicast packets
on ports that did not have IGMP reports for the multicast addresses. Linux
vxlan interfaces created via
ip link add vxlan or
systemd-networkd's netdev kind vxlan have the group option that enables
them to do the required join. By extending
ip address command with
option "autojoin" we can get similar functionality for openvswitch
(OVS) vxlan interfaces as well as other tunneling mechanisms that need to
receive multicast traffic. Defaults to "no".
Added in version 232.
NetLabel=label
This setting provides a method for integrating static and
dynamic network configuration into Linux
NetLabel[16] subsystem rules,
used by
Linux Security Modules (LSMs)[17] for network access control.
The label, with suitable LSM rules, can be used to control connectivity of
(for example) a service with peers in the local network. At least with
SELinux, only the ingress can be controlled but not egress. The benefit of
using this setting is that it may be possible to apply interface independent
part of NetLabel configuration at very early stage of system boot sequence, at
the time when the network interfaces are not available yet, with
netlabelctl(8), and the per-interface configuration with
systemd-networkd once the interfaces appear later. Currently this
feature is only implemented for SELinux.
The option expects a single NetLabel label. The label must conform
to lexical restrictions of LSM labels. When an interface is configured with
IP addresses, the addresses and subnetwork masks will be appended to the
NetLabel Fallback Peer Labeling[18] rules. They will be removed when
the interface is deconfigured. Failures to manage the labels will be
ignored.
Warning
Once labeling is enabled for network traffic, a lot of LSM access control points
in Linux networking stack go from dormant to active. Care should be taken to
avoid getting into a situation where for example remote connectivity is
broken, when the security policy has not been updated to consider LSM
per-packet access controls and no rules would allow any network traffic. Also
note that additional configuration with
netlabelctl(8) is needed.
Example:
[Address]
NetLabel=system_u:object_r:localnet_peer_t:s0
With the example rules applying for interface "eth0",
when the interface is configured with an IPv4 address of 10.0.0.123/8,
systemd-networkd performs the equivalent of netlabelctl
operation
netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0
and the reverse operation when the IPv4 address is deconfigured.
The configuration can be used with LSM rules; in case of SELinux to allow a
SELinux domain to receive data from objects of SELinux "peer"
class. For example:
type localnet_peer_t;
allow my_server_t localnet_peer_t:peer recv;
The effect of the above configuration and rules (in absence of
other rules as may be the case) is to only allow "my_server_t"
(and nothing else) to receive data from local subnet 10.0.0.0/8 of interface
"eth0".
Added in version 252.
NFTSet=source:family:table:set
This setting provides a method for integrating network
configuration into firewall rules with
NFT[19] sets. The benefit of
using the setting is that static network configuration (or dynamically
obtained network addresses, see similar directives in other sections) can be
used in firewall rules with the indirection of NFT set types. For example,
access could be granted for hosts in the local subnetwork only. Firewall rules
using IP address of an interface are also instantly updated when the network
configuration changes, for example via DHCP.
This option expects a whitespace separated list of NFT set
definitions. Each definition consists of a colon-separated tuple of source
type (one of "address", "prefix" or
"ifindex"), NFT address family (one of "arp",
"bridge", "inet", "ip", "ip6", or
"netdev"), table name and set name. The names of tables and sets
must conform to lexical restrictions of NFT table names. The type of the
element used in the NFT filter must match the type implied by the directive
("address", "prefix" or "ifindex") and address
type (IPv4 or IPv6) as shown in the table below.
Table 1. Defined source type
values
| Source type |
Description |
Corresponding NFT type name |
| "address" |
host IP address |
"ipv4_addr" or "ipv6_addr" |
| "prefix" |
network prefix |
"ipv4_addr" or "ipv6_addr", with "flags
interval" |
| "ifindex" |
interface index |
"iface_index" |
When an interface is configured with IP addresses, the addresses,
subnetwork masks or interface index will be appended to the NFT sets. The
information will be removed when the interface is deconfigured.
systemd-networkd only inserts elements to (or removes from) the sets,
so the related NFT rules, tables and sets must be prepared elsewhere in
advance. Failures to manage the sets will be ignored.
Example:
[Address]
NFTSet=prefix:netdev:filter:eth_ipv4_prefix
Corresponding NFT rules:
table netdev filter {
set eth_ipv4_prefix {
type ipv4_addr
flags interval
}
chain eth_ingress {
type filter hook ingress device "eth0" priority filter; policy drop;
ip daddr != @eth_ipv4_prefix drop
accept
}
}
Added in version 255.
[NEIGHBOR] SECTION OPTIONS¶
A [Neighbor] section accepts the following keys. The neighbor
section adds a permanent, static entry to the neighbor table (IPv6) or ARP
table (IPv4) for the given hardware address on the links matched for the
network. Specify several [Neighbor] sections to configure several static
neighbors.
Address=
The IP address of the neighbor.
Added in version 240.
LinkLayerAddress=
The link layer address (MAC address or IP address) of the
neighbor.
Added in version 243.
[IPV6ADDRESSLABEL] SECTION OPTIONS¶
An [IPv6AddressLabel] section accepts the following keys. Specify
several [IPv6AddressLabel] sections to configure several address labels.
IPv6 address labels are used for address selection. See RFC 3484[20].
Precedence is managed by userspace, and only the label itself is stored in
the kernel.
Label=
The label for the prefix. Takes an unsigned integer in
the range 0...4294967294 (0xfffffffe). 4294967295 (0xffffffff) is reserved.
This setting is mandatory.
Added in version 234.
Prefix=
Takes an IPv6 address with a prefix length, separated by
a slash "/" character. This setting is mandatory.
Added in version 234.
[ROUTINGPOLICYRULE] SECTION OPTIONS¶
An [RoutingPolicyRule] section accepts the following settings.
Specify several [RoutingPolicyRule] sections to configure several rules.
TypeOfService=
This specifies the Type of Service (ToS) field of packets
to match; it takes an unsigned integer in the range 0...255. The field can be
used to specify precedence (the first 3 bits) and ToS (the next 3 bits). The
field can be also used to specify Differentiated Services Code Point (DSCP)
(the first 6 bits) and Explicit Congestion Notification (ECN) (the last 2
bits). See
Type of Service[21] and
Differentiated services[22]
for more details.
Added in version 235.
From=
Specifies the source address prefix to match. Possibly
followed by a slash and the prefix length.
Added in version 235.
To=
Specifies the destination address prefix to match.
Possibly followed by a slash and the prefix length.
Added in version 235.
FirewallMark=
Specifies the iptables firewall mark value to match (a
number in the range 0...4294967295). Optionally, the firewall mask (also a
number between 0...4294967295) can be suffixed with a slash ("/"),
e.g., "7/255". When the mark value is non-zero and no mask is
explicitly specified, all bits of the mark are compared.
Added in version 235.
Table=
Specifies the routing table identifier to look up if the
rule selector matches. Takes one of predefined names "default",
"main", and "local", and names defined in
RouteTable= in
networkd.conf(5), or a number between 1 and
4294967295. Defaults to "main". Ignored if
L3MasterDevice= is
true.
Added in version 235.
Priority=
Specifies the priority of this rule.
Priority= is
an integer in the range 0...4294967295. Higher number means lower priority,
and rules get processed in order of increasing number. Defaults to unset, and
the kernel will pick a value dynamically.
Added in version 235.
GoTo=
Specifies the target priority used by the
"goto" type of rule. Takes an integer in the range 1...4294967295.
This must be larger than the priority of the rule specified in
Priority=. When specified,
Type=goto is implied. This is
mandatory when
Type=goto.
Added in version 257.
IncomingInterface=
Specifies incoming device to match. If the interface is
loopback, the rule only matches packets originating from this host.
Added in version 236.
OutgoingInterface=
Specifies the outgoing device to match. The outgoing
interface is only available for packets originating from local sockets that
are bound to a device.
Added in version 236.
L3MasterDevice=
Takes a boolean. Specifies whether the rule is to direct
lookups to the tables associated with level 3 master devices (also known as
Virtual Routing and Forwarding or VRF devices). For further details see
Virtual Routing and Forwarding (VRF)[23]. Defaults to false.
Added in version 256.
SourcePort=
Specifies the source IP port or IP port range match in
forwarding information base (FIB) rules. A port range is specified by the
lower and upper port separated by a dash. Defaults to unset.
Added in version 240.
DestinationPort=
Specifies the destination IP port or IP port range match
in forwarding information base (FIB) rules. A port range is specified by the
lower and upper port separated by a dash. Defaults to unset.
Added in version 240.
IPProtocol=
Specifies the IP protocol to match in forwarding
information base (FIB) rules. Takes IP protocol name such as "tcp",
"udp" or "sctp", or IP protocol number such as
"6" for "tcp" or "17" for "udp".
Defaults to unset.
Added in version 240.
InvertRule=
A boolean. Specifies whether the rule is to be inverted.
Defaults to false.
Added in version 240.
Family=
Takes a special value "ipv4", "ipv6",
or "both". By default, the address family is determined by the
address specified in
To= or
From=. If neither
To= nor
From= are specified, then defaults to "ipv4".
Added in version 243.
User=
Takes a username, a user ID, or a range of user IDs
separated by a dash. Defaults to unset.
Added in version 245.
SuppressPrefixLength=
Takes a number
N in the range 0...128 and rejects
routing decisions that have a prefix length of
N or less. Defaults to
unset.
Added in version 245.
SuppressInterfaceGroup=
Takes an integer in the range 0...2147483647 and rejects
routing decisions that have an interface with the same group id. It has the
same meaning as
suppress_ifgroup in
ip rule. Defaults to unset.
Added in version 250.
Type=
Specifies Routing Policy Database (RPDB) rule type. Takes
one of "table", "goto", "nop",
"blackhole", "unreachable", or "prohibit". When
"goto", the target priority must be specified in
GoTo=.
Defaults to "table".
Added in version 248.
[NEXTHOP] SECTION OPTIONS¶
The [NextHop] section is used to manipulate entries in the
kernel's "nexthop" tables. The [NextHop] section accepts the
following settings. Specify several [NextHop] sections to configure several
hops.
Id=
The id of the next hop. Takes an integer in the range
1...4294967295. This is mandatory if
ManageForeignNextHops=no is
specified in
networkd.conf(5). Otherwise, if unspecified, an unused ID
will be automatically picked.
Added in version 244.
Gateway=
As in the [Network] section.
Added in version 244.
Family=
Takes one of the special values "ipv4" or
"ipv6". By default, the family is determined by the address
specified in
Gateway=. If
Gateway= is not specified, then
defaults to "ipv4".
Added in version 248.
OnLink=
Takes a boolean. If set to true, the kernel does not have
to check if the gateway is reachable directly by the current machine (i.e.,
attached to the local network), so that we can insert the nexthop in the
kernel table without it being complained about. Defaults to "no".
Added in version 248.
Blackhole=
Takes a boolean. If enabled, packets to the corresponding
routes are discarded silently, and
Gateway= cannot be specified.
Defaults to "no".
Added in version 248.
Group=
Takes a whitespace separated list of nexthop IDs. Each ID
must be in the range 1...4294967295. Optionally, each nexthop ID can take a
weight after a colon ("
id[:
weight]"). The weight must
be in the range 1...255. If the weight is not specified, then it is assumed
that the weight is 1. This setting cannot be specified with
Gateway=,
Family=,
Blackhole=. This setting can be specified multiple
times. If an empty string is assigned, then the all previous assignments are
cleared. Defaults to unset.
Added in version 249.
[ROUTE] SECTION OPTIONS¶
The [Route] section accepts the following settings. Specify
several [Route] sections to configure several routes.
Gateway=
Takes the gateway address or the special values
"_dhcp4" and "_ipv6ra". If "_dhcp4" or
"_ipv6ra" is set, then the gateway address provided by DHCPv4 or
IPv6 RA is used.
Added in version 211.
GatewayOnLink=
Takes a boolean. If set to true, the kernel does not have
to check if the gateway is reachable directly by the current machine (i.e.,
attached to the local network), so that we can insert the route in the kernel
table without it being complained about. Defaults to "no".
Added in version 234.
Destination=
The destination prefix of the route. Possibly followed by
a slash and the prefix length. If omitted, a full-length host route is
assumed.
Added in version 211.
Source=
The source prefix of the route. Possibly followed by a
slash and the prefix length. If omitted, a full-length host route is assumed.
Added in version 218.
Metric=
The metric of the route. Takes an unsigned integer in the
range 0...4294967295. Defaults to unset, and the kernel's default will be
used.
Added in version 216.
IPv6Preference=
Specifies the route preference as defined in
RFC
4191[24] for Router Discovery messages. Which can be one of
"low" the route has a lowest priority, "medium" the route
has a default priority or "high" the route has a highest priority.
Added in version 234.
Scope=
The scope of the IPv4 route, which can be
"global", "site", "link", "host", or
"nowhere":
•"global" means the route can reach
hosts more than one hop away.
•"site" means an interior route in the
local autonomous system.
•"link" means the route can only reach
hosts on the local network (one hop away).
•"host" means the route will not leave
the local machine (used for internal addresses like 127.0.0.1).
•"nowhere" means the destination does
not exist.
For IPv4 route, defaults to "host" if Type= is
"local" or "nat", and "link" if Type=
is "broadcast", "multicast", "anycast", or
"unicast". In other cases, defaults to "global". The
value is not used for IPv6.
Added in version 219.
PreferredSource=
The preferred source address of the route. The address
must be in the format described in
inet_pton(3).
Added in version 227.
Table=
The table identifier for the route. Takes one of
predefined names "default", "main", and "local",
and names defined in
RouteTable= in
networkd.conf(5), or a
number between 1 and 4294967295. The table can be retrieved using
ip route
show table num. If unset and
Type= is
"local", "broadcast", "anycast", or
"nat", then "local" is used. In other cases, defaults to
"main".
Added in version 230.
HopLimit=
Configures per route hop limit. Takes an integer in the
range 1...255. See also
IPv6HopLimit=.
Added in version 255.
Protocol=
The protocol identifier for the route. Takes a number
between 0 and 255 or the special values "kernel", "boot",
"static", "ra" and "dhcp". Defaults to
"static".
Added in version 234.
Type=
Specifies the type for the route. Takes one of
"unicast", "local", "broadcast",
"anycast", "multicast", "blackhole",
"unreachable", "prohibit", "throw",
"nat", and "xresolve". If "unicast", a regular
route is defined, i.e. a route indicating the path to take to a destination
network address. If "blackhole", packets to the defined route are
discarded silently. If "unreachable", packets to the defined route
are discarded and the ICMP message "Host Unreachable" is generated.
If "prohibit", packets to the defined route are discarded and the
ICMP message "Communication Administratively Prohibited" is
generated. If "throw", route lookup in the current routing table
will fail and the route selection process will return to Routing Policy
Database (RPDB). Defaults to "unicast".
Added in version 235.
InitialCongestionWindow=
The TCP initial congestion window is used during the
start of a TCP connection. During the start of a TCP session, when a client
requests a resource, the server's initial congestion window determines how
many packets will be sent during the initial burst of data without waiting for
acknowledgement. Takes a number between 1 and 1023. Note that 100 is
considered an extremely large value for this option. When unset, the kernel's
default (typically 10) will be used.
Added in version 237.
InitialAdvertisedReceiveWindow=
The TCP initial advertised receive window is the amount
of receive data (in bytes) that can initially be buffered at one time on a
connection. The sending host can send only that amount of data before waiting
for an acknowledgment and window update from the receiving host. Takes a
number between 1 and 1023. Note that 100 is considered an extremely large
value for this option. When unset, the kernel's default will be used.
Added in version 237.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode for
the route is enabled. When unset, the kernel's default will be used.
Added in version 237.
FastOpenNoCookie=
Takes a boolean. When true enables TCP fastopen without a
cookie on a per-route basis. When unset, the kernel's default will be used.
Added in version 243.
MTUBytes=
The maximum transmission unit in bytes to set for the
route. The usual suffixes K, M, G, are supported and are understood to the
base of 1024.
Added in version 239.
TCPAdvertisedMaximumSegmentSize=
Specifies the Path MSS (in bytes) hints given on TCP
layer. The usual suffixes K, M, G, are supported and are understood to the
base of 1024. An unsigned integer in the range 1...4294967294. When unset, the
kernel's default will be used.
Added in version 248.
TCPCongestionControlAlgorithm=
Specifies the TCP congestion control algorithm for the
route. Takes a name of the algorithm, e.g. "bbr", "dctcp",
or "vegas". When unset, the kernel's default will be used.
Added in version 252.
TCPRetransmissionTimeoutSec=
Specifies the TCP Retransmission Timeout (RTO) for the
route. Takes time values in seconds. This value specifies the timeout of an
alive TCP connection, when retransmissions remain unacknowledged. When unset,
the kernel's default will be used.
Added in version 255.
MultiPathRoute=address[@name]
[weight]
Configures multipath route. Multipath routing is the
technique of using multiple alternative paths through a network. Takes gateway
address. Optionally, takes a network interface name or index separated with
"@", and a weight in 1..256 for this multipath route separated with
whitespace. This setting can be specified multiple times. If an empty string
is assigned, then the all previous assignments are cleared.
Added in version 245.
NextHop=
Specifies the nexthop id. Takes an unsigned integer in
the range 1...4294967295. If set, the corresponding [NextHop] section must be
configured. Defaults to unset.
Added in version 248.
[DHCPV4] SECTION OPTIONS¶
The [DHCPv4] section configures the DHCPv4 client, if it is
enabled with the DHCP= setting described above:
RequestAddress=
Takes an IPv4 address. When specified, the Requested IP
Address option (option code 50) is added with it to the initial DHCPDISCOVER
message sent by the DHCP client. Defaults to unset, and an already assigned
dynamic address to the interface is automatically picked.
Added in version 255.
SendHostname=
When true (the default), the machine's hostname (or the
value specified with
Hostname=, described below) will be sent to the
DHCP server. Note that the hostname must consist only of 7-bit ASCII
lower-case characters and no spaces or dots, and be formatted as a valid DNS
domain name. Otherwise, the hostname is not sent even if this option is true.
Added in version 215.
Hostname=
Use this value for the hostname which is sent to the DHCP
server, instead of machine's hostname. Note that the specified hostname must
consist only of 7-bit ASCII lower-case characters and no spaces or dots, and
be formatted as a valid DNS domain name.
Added in version 223.
MUDURL=
When configured, the specified Manufacturer Usage
Description (MUD) URL will be sent to the DHCPv4 server. Takes a URL of length
up to 255 characters. A superficial verification that the string is a valid
URL will be performed. DHCPv4 clients are intended to have at most one MUD URL
associated with them. See
RFC 8520[25].
MUD is an embedded software standard defined by the IETF that
allows IoT device makers to advertise device specifications, including the
intended communication patterns for their device when it connects to the
network. The network can then use this to author a context-specific access
policy, so the device functions only within those parameters.
Added in version 246.
ClientIdentifier=
The DHCPv4 client identifier to use. Takes one of
mac or
duid. If set to
mac, the MAC address of the link
is used. If set to
duid, an RFC4361-compliant Client ID, which is the
combination of IAID and DUID, is used. IAID can be configured by
IAID=.
DUID can be configured by
DUIDType= and
DUIDRawData=. Defaults
to
duid.
Added in version 220.
VendorClassIdentifier=
The vendor class identifier used to identify vendor type
and configuration.
Added in version 216.
UserClass=
A DHCPv4 client can use UserClass option to identify the
type or category of user or applications it represents. The information
contained in this option is a string that represents the user class of which
the client is a member. Each class sets an identifying string of information
to be used by the DHCP service to classify clients. Takes a
whitespace-separated list of strings.
Added in version 239.
DUIDType=
Override the global
DUIDType= setting for this
network. See
networkd.conf(5) for a description of possible values.
Added in version 230.
DUIDRawData=
Override the global
DUIDRawData= setting for this
network. See
networkd.conf(5) for a description of possible values.
Added in version 230.
IAID=
The DHCP Identity Association Identifier (IAID) for the
interface, a 32-bit unsigned integer.
Added in version 230.
RapidCommit=
Takes a boolean. The DHCPv4 client can obtain
configuration parameters from a DHCPv4 server through a rapid two-message
exchange (discover and ack). When the rapid commit option is set by both the
DHCPv4 client and the DHCPv4 server, the two-message exchange is used.
Otherwise, the four-message exchange (discover, offer, request, and ack) is
used. The two-message exchange provides faster client configuration. See
RFC 4039[26] for details. Defaults to true when
Anonymize=no and
neither
AllowList= nor
DenyList= is specified, and false
otherwise.
Added in version 255.
Anonymize=
Takes a boolean. When true, the options sent to the DHCP
server will follow the
RFC 7844[27] (Anonymity Profiles for DHCP
Clients) to minimize disclosure of identifying information. Defaults to false.
This option should only be set to true when
MACAddressPolicy= is set to random (see
systemd.link(5)).
When true, ClientIdentifier=mac, RapidCommit=no,
SendHostname=no, Use6RD=no, UseCaptivePortal=no,
UseMTU=no, UseNTP=no, UseSIP=no, and
UseTimezone=no are implied and these settings in the .network file
are silently ignored. Also, Hostname=, MUDURL=,
RequestAddress=, RequestOptions=, SendOption=,
SendVendorOption=, UserClass=, and
VendorClassIdentifier= are silently ignored.
With this option enabled DHCP requests will mimic those generated
by Microsoft Windows, in order to reduce the ability to fingerprint and
recognize installations. This means DHCP request sizes will grow and lease
data will be more comprehensive than normally, though most of the requested
data is not actually used.
Added in version 235.
RequestOptions=
Sets request options to be sent to the server in the
DHCPv4 request options list. A whitespace-separated list of integers in the
range 1...254. Defaults to unset.
Added in version 244.
SendOption=
Send an arbitrary raw option in the DHCPv4 request. Takes
a DHCP option number, data type and data separated with a colon
("
option:
type:
value"). The option number must
be an integer in the range 1...254. The type takes one of "uint8",
"uint16", "uint32", "ipv4address", or
"string". Special characters in the data string may be escaped using
C-style escapes[28]. This setting can be specified multiple times. If
an empty string is specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 244.
SendVendorOption=
Send an arbitrary vendor option in the DHCPv4 request.
Takes a DHCP option number, data type and data separated with a colon
("
option:
type:
value"). The option number must
be an integer in the range 1...254. The type takes one of "uint8",
"uint16", "uint32", "ipv4address", or
"string". Special characters in the data string may be escaped using
C-style escapes[28]. This setting can be specified multiple times. If
an empty string is specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 246.
IPServiceType=
Takes one of the special values "none",
"CS6", or "CS4". When "none" no IP service type
is set to the packet sent from the DHCPv4 client. When "CS6"
(network control) or "CS4" (realtime), the corresponding service
type will be set. Defaults to "CS6".
Added in version 244.
SocketPriority=
The Linux socket option
SO_PRIORITY applied to the
raw IP socket used for initial DHCPv4 messages. Unset by default. Usual values
range from 0 to 6. More details about
SO_PRIORITY socket option in
socket(7). Can be used in conjunction with [VLAN] section
EgressQOSMaps= setting of .netdev file to set the 802.1Q VLAN ethernet
tagged header priority, see
systemd.netdev(5).
Added in version 253.
Label=
Specifies the label for the IPv4 address received from
the DHCP server. The label must be a 7-bit ASCII string with a length of
1...15 characters. Defaults to unset.
Added in version 250.
UseDNS=
When true (the default), the DNS servers received from
the DHCP server will be used.
This corresponds to the nameserver option in
resolv.conf(5).
Added in version 211.
RoutesToDNS=
When true, the routes to the DNS servers received from
the DHCP server will be configured. When
UseDNS= is disabled, this
setting is ignored. Defaults to true.
Added in version 243.
UseNTP=
When true (the default), the NTP servers received from
the DHCP server will be used by systemd-timesyncd.service.
Added in version 220.
RoutesToNTP=
When true, the routes to the NTP servers received from
the DHCP server will be configured. When
UseNTP= is disabled, this
setting is ignored. Defaults to true.
Added in version 249.
UseSIP=
When true (the default), the SIP servers received from
the DHCP server will be collected and made available to client programs.
Added in version 244.
UseCaptivePortal=
When true (the default), the captive portal advertised by
the DHCP server will be recorded and made available to client programs and
displayed in the
networkctl(1) status output per-link.
Added in version 254.
UseDNR=
When true, designated resolvers advertised by the DHCP
server will be used as encrypted DNS servers. See
RFC 9463[29].
Defaults to unset, and the value for UseDNS= will be
used.
Added in version 257.
UseMTU=
When true, the interface maximum transmission unit from
the DHCP server will be used on the current link. If
MTUBytes= is set,
then this setting is ignored. Defaults to false.
Note, some drivers will reset the interfaces if the MTU is
changed. For such interfaces, please try to use IgnoreCarrierLoss=
with a short timespan, e.g. "3 seconds".
Added in version 211.
UseHostname=
When true (the default), the hostname received from the
DHCP server will be set as the transient hostname of the system.
Added in version 211.
UseDomains=
Takes a boolean, or the special value
route. When
true, the domain name received from the DHCP server will be used as DNS search
domain over this link, similarly to the effect of the
Domains= setting.
If set to
route, the domain name received from the DHCP server will be
used for routing DNS queries only, but not for searching, similarly to the
effect of the
Domains= setting when the argument is prefixed with
"~".
When unspecified, the value specified in the same setting in the
[Network] section will be used. When it is unspecified, the value specified
in the same setting in the [DHCPv4] section in networkd.conf(5) will
be used. When it is unspecified, the value specified in the same setting in
the [Network] section in networkd.conf(5) will be used. When none of
them are specified, defaults to "no".
It is recommended to enable this option only on trusted networks,
as setting this affects resolution of all hostnames, in particular of
single-label names. It is generally safer to use the supplied domain only as
routing domain, rather than as search domain, in order to not have it affect
local resolution of single-label names.
When set to true, this setting corresponds to the domain
option in resolv.conf(5).
Added in version 216.
UseRoutes=
When true (the default), the static routes will be
requested from the DHCP server and added to the routing table with a metric of
1024, and a scope of
global,
link or
host, depending on
the route's destination and gateway. If the destination is on the local host,
e.g., 127.x.x.x, or the same as the link's own address, the scope will be set
to
host. Otherwise, if the gateway is null (a direct route), a
link scope will be used. For anything else, scope defaults to
global.
Added in version 215.
RouteMetric=
Set the routing metric for routes specified by the DHCP
server (including the prefix route added for the specified prefix). Takes an
unsigned integer in the range 0...4294967295. Defaults to 1024.
Added in version 217.
RouteTable=num
The table identifier for DHCP routes. Takes one of
predefined names "default", "main", and "local",
and names defined in
RouteTable= in
networkd.conf(5), or a
number between 1...4294967295.
When used in combination with VRF=, the VRF's routing table
is used when this parameter is not specified.
Added in version 232.
RouteMTUBytes=
Specifies the MTU for the DHCP routes. Please see the
[Route] section for further details.
Added in version 245.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode is
enabled for the routes configured by the acquired DHCPv4 lease. When unset,
the kernel's default will be used.
Added in version 253.
InitialCongestionWindow=
As in the [Route] section.
Added in version 255.
InitialAdvertisedReceiveWindow=
As in the [Route] section.
Added in version 255.
UseGateway=
When true, and the DHCP server provides a Router option,
the default gateway based on the router address will be configured. Defaults
to unset, and the value specified with
UseRoutes= will be used.
Note, when the server provides both the Router and Classless
Static Routes option, and UseRoutes= is enabled, the Router option is
always ignored regardless of this setting. See RFC 3442[30].
Added in version 246.
UseTimezone=
When true, the timezone received from the DHCP server
will be set as timezone of the local system. Defaults to false.
Added in version 226.
Use6RD=
When true, subnets of the received IPv6 prefix are
assigned to downstream interfaces which enables
DHCPPrefixDelegation=.
See also
DHCPPrefixDelegation= in the [Network] section, the
[DHCPPrefixDelegation] section, and
RFC 5969[31]. Defaults to false.
Added in version 250.
UnassignedSubnetPolicy=
Takes "none", or one of the reject types:
"unreachable", "prohibit", "blackhole", or
"throw". If a reject type is specified, the reject route
corresponding to the acquired 6RD prefix will be configured. For example, when
"unreachable",
unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium
will be configured. See RFC 7084[32]. If "none"
is specified, such route will not be configured. This may be useful when
custom firewall rules that handle packets for unassigned subnets will be
configured. Defaults to "unreachable".
Added in version 257.
IPv6OnlyMode=
When true, the DHCPv4 configuration will be delayed by
the timespan provided by the DHCP server and skip to configure dynamic IPv4
network connectivity if IPv6 connectivity is provided within the timespan. See
RFC 8925[33]. Defaults to false.
Added in version 255.
FallbackLeaseLifetimeSec=
Allows one to set DHCPv4 lease lifetime when DHCPv4
server does not send the lease lifetime. Takes one of "forever" or
"infinity". If specified, the acquired address never expires.
Defaults to unset.
Added in version 246.
RequestBroadcast=
Request the server to use broadcast messages before the
IP address has been configured. This is necessary for devices that cannot
receive RAW packets, or that cannot receive packets at all before an IP
address has been configured. On the other hand, this must not be enabled on
networks where broadcasts are filtered out.
Added in version 216.
MaxAttempts=
Specifies how many times the DHCPv4 client configuration
should be attempted. Takes a number or "infinity". Defaults to
"infinity". Note that the time between retries is increased
exponentially, up to approximately one per minute, so the network will not be
overloaded even if this number is high. The default is suitable in most
circumstances.
Added in version 243.
ListenPort=
Set the port from which the DHCP client packets
originate.
Added in version 233.
ServerPort=
Set the port on which the DHCP server is listening.
Added in version 256.
DenyList=
A whitespace-separated list of IPv4 addresses. Each
address can optionally take a prefix length after "/". DHCP offers
from servers in the list are rejected. Note that if
AllowList= is
configured then
DenyList= is ignored.
Note that this filters only DHCP offers, so the filtering might
not work when RapidCommit= is enabled. See also RapidCommit=
above.
Added in version 246.
AllowList=
A whitespace-separated list of IPv4 addresses. Each
address can optionally take a prefix length after "/". DHCP offers
from servers in the list are accepted.
Note that this filters only DHCP offers, so the filtering might
not work when RapidCommit= is enabled. See also RapidCommit=
above.
Added in version 246.
SendRelease=
When true, the DHCPv4 client sends a DHCP release packet
when it stops. Defaults to true.
Added in version 243.
SendDecline=
A boolean. When true,
systemd-networkd performs
IPv4 Duplicate Address Detection to the acquired address by the DHCPv4 client.
If duplicate is detected, the DHCPv4 client rejects the address by sending a
DHCPDECLINE packet to the DHCP server, and tries to obtain an IP
address again. See
RFC 5227[8]. Defaults to false.
Added in version 245.
NetLabel=
This applies the NetLabel for the addresses received with
DHCP, like
NetLabel= in [Address] section applies it to statically
configured addresses. See
NetLabel= in [Address] section for more
details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like
NFTSet= in [Address] section applies it to
static configuration. See
NFTSet= in [Address] section for more
details. For "address" or "prefix" source types, the type
of the element used in the NFT filter must be "ipv4_addr".
Added in version 255.
[DHCPV6] SECTION OPTIONS¶
The [DHCPv6] section configures the DHCPv6 client, if it is
enabled with the DHCP= setting described above, or invoked by the
IPv6 Router Advertisement:
MUDURL=, IAID=, DUIDType=,
DUIDRawData=, RequestOptions=
As in the [DHCPv4] section.
Added in version 246.
SendOption=
As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option numbers, the option number is an integer in the
range 1...65536.
Added in version 246.
SendVendorOption=
Send an arbitrary vendor option in the DHCPv6 request.
Takes an enterprise identifier, DHCP option number, data type, and data
separated with a colon ("
enterprise
identifier:
option:
type:
value"). Enterprise
identifier is an unsigned integer in the range 1...4294967294. The option
number must be an integer in the range 1...254. Data type takes one of
"uint8", "uint16", "uint32",
"ipv4address", "ipv6address", or "string".
Special characters in the data string may be escaped using
C-style
escapes[28]. This setting can be specified multiple times. If an empty
string is specified, then all options specified earlier are cleared. Defaults
to unset.
Added in version 246.
UserClass=
A DHCPv6 client can use User Class option to identify the
type or category of user or applications it represents. The information
contained in this option is a string that represents the user class of which
the client is a member. Each class sets an identifying string of information
to be used by the DHCP service to classify clients. Special characters in the
data string may be escaped using
C-style escapes[28]. This setting can
be specified multiple times. If an empty string is specified, then all options
specified earlier are cleared. Takes a whitespace-separated list of strings.
Note that currently
NUL bytes are not allowed.
Added in version 246.
VendorClass=
A DHCPv6 client can use VendorClass option to identify
the vendor that manufactured the hardware on which the client is running. The
information contained in the data area of this option is contained in one or
more opaque fields that identify details of the hardware configuration. Takes
a whitespace-separated list of strings.
Added in version 246.
PrefixDelegationHint=
Takes an IPv6 address with prefix length in the same
format as the
Address= in the [Network] section. The DHCPv6 client will
include a prefix hint in the DHCPv6 solicitation sent to the server. The
prefix length must be in the range 1...128. Defaults to unset.
Added in version 244.
UnassignedSubnetPolicy=
Takes "none" or one of the reject types:
"unreachable", "prohibit", "blackhole", or
"throw". If a reject type is specified, the reject route
corresponding to the delegated prefix will be configured. For example, when
"unreachable",
unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium
will be configured. See RFC 7084[32]. If "none"
is specified, such route will not be configured. This may be useful when
custom firewall rules that handle packets for unassigned subnets will be
configured. Defaults to "unreachable".
Added in version 257.
RapidCommit=
Takes a boolean. The DHCPv6 client can obtain
configuration parameters from a DHCPv6 server through a rapid two-message
exchange (solicit and reply). When the rapid commit option is set by both the
DHCPv6 client and the DHCPv6 server, the two-message exchange is used.
Otherwise, the four-message exchange (solicit, advertise, request, and reply)
is used. The two-message exchange provides faster client configuration. See
RFC 3315[34] for details. Defaults to true, and the two-message
exchange will be used if the server support it.
Added in version 252.
SendHostname=
When true (the default), the machine's hostname (or the
value specified with
Hostname=, described below) will be sent to the
DHCPv6 server. Note that the hostname must consist only of 7-bit ASCII
lower-case characters and no spaces or dots, and be formatted as a valid DNS
domain name. Otherwise, the hostname is not sent even if this option is true.
Added in version 255.
Hostname=
Use this value for the hostname which is sent to the
DHCPv6 server, instead of machine's hostname. Note that the specified hostname
must consist only of 7-bit ASCII lower-case characters and no spaces or dots,
and be formatted as a valid DNS domain name.
Added in version 255.
UseAddress=
When true (the default), the IP addresses provided by the
DHCPv6 server will be assigned.
Added in version 248.
UseCaptivePortal=
When true (the default), the captive portal advertised by
the DHCPv6 server will be recorded and made available to client programs and
displayed in the
networkctl(1) status output per-link.
Added in version 254.
UseDelegatedPrefix=
When true (the default), the client will request the
DHCPv6 server to delegate prefixes. If the server provides prefixes to be
delegated, then subnets of the prefixes are assigned to the interfaces that
have
DHCPPrefixDelegation=yes. See also the
DHCPPrefixDelegation= setting in the [Network] section, settings in the
[DHCPPrefixDelegation] section, and
RFC 8415[35].
Added in version 250.
UseDNS=, UseDNR=, UseNTP=,
UseHostname=, UseDomains=, NetLabel=,
SendRelease=
As in the [DHCPv4] section.
Added in version 243.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like
NFTSet= in [Address] section applies it to
static configuration. See
NFTSet= in [Address] section for more
details. For "address" or "prefix" source types, the type
of the element used in the NFT filter must be "ipv6_addr".
Added in version 255.
WithoutRA=
Allows DHCPv6 client to start without router
advertisements's "managed" or "other configuration" flag.
Takes one of "no", "solicit", or
"information-request". If this is not specified, "solicit"
is used when
DHCPPrefixDelegation= is enabled and
UplinkInterface=:self is specified in the [DHCPPrefixDelegation]
section. Otherwise, defaults to "no", and the DHCPv6 client will be
started when an RA is received. See also the
DHCPv6Client= setting in
the [IPv6AcceptRA] section.
Added in version 246.
[DHCPPREFIXDELEGATION] SECTION OPTIONS¶
The [DHCPPrefixDelegation] section configures subnet prefixes of
the delegated prefixes acquired by a DHCPv6 client or by a DHCPv4 client
through the 6RD option on another interface. The settings in this section
are used only when the DHCPPrefixDelegation= setting in the [Network]
section is enabled.
UplinkInterface=
Specifies the name or the index of the uplink interface,
or one of the special values ":self" and ":auto". When
":self", the interface itself is considered the uplink interface,
and
WithoutRA=solicit is implied if the setting is not explicitly
specified. When ":auto", the first link which acquired prefixes to
be delegated from the DHCPv6 or DHCPv4 server is selected. Defaults to
":auto".
Added in version 250.
SubnetId=
Configure a specific subnet ID on the interface from a
(previously) received prefix delegation. You can either set "auto"
(the default) or a specific subnet ID (as defined in
RFC 4291[36],
section 2.5.4), in which case the allowed value is hexadecimal, from 0 to
0x7fffffffffffffff inclusive.
Added in version 246.
Announce=
Takes a boolean. When enabled, and
IPv6SendRA= in
[Network] section is enabled, the delegated prefixes are distributed through
the IPv6 Router Advertisement. This setting will be ignored when the
DHCPPrefixDelegation= setting is enabled on the upstream interface.
Defaults to yes.
Added in version 247.
Assign=
Takes a boolean. Specifies whether to add an address from
the delegated prefixes which are received from the WAN interface by the DHCPv6
Prefix Delegation. When true (on LAN interface), the EUI-64 algorithm will be
used by default to form an interface identifier from the delegated prefixes.
See also
Token= setting below. Defaults to yes.
Added in version 246.
Token=
Specifies an optional address generation mode for
assigning an address in each delegated prefix. This accepts the same syntax as
Token= in the [IPv6AcceptRA] section. If
Assign= is set to
false, then this setting will be ignored. Defaults to unset, which means the
EUI-64 algorithm will be used.
Added in version 246.
ManageTemporaryAddress=
As in the [Address] section, but defaults to true.
Added in version 248.
RouteMetric=
The metric of the route to the delegated prefix subnet.
Takes an unsigned integer in the range 0...4294967295. When set to 0, the
kernel's default value is used. Defaults to 256.
Added in version 249.
NetLabel=
This applies the NetLabel for the addresses received with
DHCP, like
NetLabel= in [Address] section applies it to statically
configured addresses. See
NetLabel= in [Address] section for more
details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like
NFTSet= in [Address] section applies it to
static configuration. See
NFTSet= in [Address] section for more
details. For "address" or "prefix" source types, the type
of the element used in the NFT filter must be "ipv6_addr".
Added in version 255.
[IPV6ACCEPTRA] SECTION OPTIONS¶
The [IPv6AcceptRA] section configures the IPv6 Router
Advertisement (RA) client, if it is enabled with the IPv6AcceptRA=
setting described above:
UseRedirect=
When true (the default), Redirect message sent by the
current first-hop router will be accepted, and routes to redirected nodes will
be configured.
Added in version 256.
Token=
Specifies an optional address generation mode for the
Stateless Address Autoconfiguration (SLAAC). The following values are
supported:
eui64
The EUI-64 algorithm will be used to generate an address
for that prefix. Only supported by Ethernet or InfiniBand interfaces.
Added in version 250.
static:ADDRESS
An IPv6 address must be specified after a colon
(":"), and the lower bits of the supplied address are combined with
the upper bits of a prefix received in a Router Advertisement (RA) message to
form a complete address. Note that if multiple prefixes are received in an RA
message, or in multiple RA messages, addresses will be formed from each of
them using the supplied address. This mode implements SLAAC but uses a static
interface identifier instead of an identifier generated by using the EUI-64
algorithm. Because the interface identifier is static, if Duplicate Address
Detection detects that the computed address is a duplicate (in use by another
node on the link), then this mode will fail to provide an address for that
prefix. If an IPv6 address without mode is specified, then "static"
mode is assumed.
Added in version 250.
prefixstable[:ADDRESS][,UUID]
The algorithm specified in
RFC 7217[37] will be
used to generate interface identifiers. This mode can optionally take an IPv6
address separated with a colon (":"). If an IPv6 address is
specified, then an interface identifier is generated only when a prefix
received in an RA message matches the supplied address.
This mode can also optionally take a non-null UUID in the format
which sd_id128_from_string() accepts, e.g.
"86b123b969ba4b7eb8b3d8605123525a" or
"86b123b9-69ba-4b7e-b8b3-d8605123525a". If a UUID is specified,
the value is used as the secret key to generate interface identifiers. If
not specified, then an application specific ID generated with the system's
machine-ID will be used as the secret key. See sd-id128(3),
sd_id128_from_string(3), and sd_id128_get_machine(3).
Note that the "prefixstable" algorithm uses both the
interface name and MAC address as input to the hash to compute the interface
identifier, so if either of those are changed the resulting interface
identifier (and address) will be changed, even if the prefix received in the
RA message has not been changed.
Added in version 250.
If no address generation mode is specified (which is the default),
or a received prefix does not match any of the addresses provided in
"prefixstable" mode, then the EUI-64 algorithm will be used for
Ethernet or InfiniBand interfaces, otherwise "prefixstable" will
be used to form an interface identifier for that prefix.
This setting can be specified multiple times. If an empty string
is assigned, then the all previous assignments are cleared.
Examples:
Token=eui64
Token=::1a:2b:3c:4d
Token=static:::1a:2b:3c:4d
Token=prefixstable
Token=prefixstable:2002:da8:1::
Added in version 250.
UseDNS=
When true (the default), the DNS servers received in the
Router Advertisement will be used.
This corresponds to the nameserver option in
resolv.conf(5).
Added in version 231.
UseDNR=
When true, the DNR servers received in the Router
Advertisement will be used. Defaults to the value of
UseDNS=.
Added in version 257.
UseDomains=
Takes a boolean, or the special value "route".
When true, the domain name received via IPv6 Router Advertisement (RA) will be
used as DNS search domain over this link, similarly to the effect of the
Domains= setting. If set to "route", the domain name received
via IPv6 RA will be used for routing DNS queries only, but not for searching,
similarly to the effect of the
Domains= setting when the argument is
prefixed with "~". Defaults to false.
It is recommended to enable this option only on trusted networks,
as setting this affects resolution of all hostnames, in particular of
single-label names. It is generally safer to use the supplied domain only as
routing domain, rather than as search domain, in order to not have it affect
local resolution of single-label names.
When set to true, this setting corresponds to the domain
option in resolv.conf(5).
Added in version 231.
RouteTable=num
The table identifier for the routes received in the
Router Advertisement. Takes one of predefined names "default",
"main", and "local", and names defined in
RouteTable= in
networkd.conf(5), or a number between
1...4294967295.
When used in combination with VRF=, the VRF's routing table
is used when this parameter is not specified.
Added in version 232.
RouteMetric=
Set the routing metric for the routes received in the
Router Advertisement. Takes an unsigned integer in the range 0...4294967295,
or three unsigned integer separated with ":", in that case the first
one is used when the router preference is high, the second is for medium
preference, and the last is for low preference
("
high:
medium:
low"). Defaults to
"512:1024:2048".
Added in version 249.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode is
enabled for the routes configured by the received RAs. When unset, the
kernel's default will be used.
Added in version 253.
UseMTU=
Takes a boolean. When true, the MTU received in the
Router Advertisement will be used. Defaults to true.
Added in version 250.
UseHopLimit=
Takes a boolean. When true, the hop limit received in the
Router Advertisement will be set to routes configured based on the
advertisement. See also
IPv6HopLimit=. Defaults to true.
Added in version 255.
UseReachableTime=
Takes a boolean. When true, the reachable time received
in the Router Advertisement will be set on the interface receiving the
advertisement. It is used as the base timespan of the validity of a neighbor
entry. Defaults to true.
Added in version 256.
UseRetransmissionTime=
Takes a boolean. When true, the retransmission time
received in the Router Advertisement will be set on the interface receiving
the advertisement. It is used as the time between retransmissions of Neighbor
Solicitation messages to a neighbor when resolving the address or when probing
the reachability of a neighbor. Defaults to true.
Added in version 256.
UseGateway=
When true (the default), the router address will be
configured as the default gateway.
Added in version 250.
UseRoutePrefix=
When true (the default), the routes corresponding to the
route prefixes received in the Router Advertisement will be configured.
Added in version 250.
UseCaptivePortal=
When true (the default), the captive portal received in
the Router Advertisement will be recorded and made available to client
programs and displayed in the
networkctl(1) status output per-link.
Added in version 254.
UsePREF64=
When true, the IPv6 PREF64 (or NAT64) prefixes received
in the Router Advertisement will be recorded and made available to client
programs and displayed in the
networkctl(1) status output per-link. See
RFC 8781[38]. Defaults to false.
Added in version 255.
UseAutonomousPrefix=
When true (the default), the autonomous prefix received
in the Router Advertisement will be used and take precedence over any
statically configured ones.
Added in version 242.
UseOnLinkPrefix=
When true (the default), the onlink prefix received in
the Router Advertisement will be used and takes precedence over any statically
configured ones.
Added in version 242.
RouterDenyList=
A whitespace-separated list of IPv6 router addresses.
Each address can optionally take a prefix length after "/". Any
information advertised by the listed router is ignored.
Added in version 248.
RouterAllowList=
A whitespace-separated list of IPv6 router addresses.
Each address can optionally take a prefix length after "/". Only
information advertised by the listed router is accepted. Note that if
RouterAllowList= is configured then
RouterDenyList= is ignored.
Added in version 248.
PrefixDenyList=
A whitespace-separated list of IPv6 prefixes. Each prefix
can optionally take its prefix length after "/". IPv6 prefixes
supplied via router advertisements in the list are ignored.
Added in version 248.
PrefixAllowList=
A whitespace-separated list of IPv6 prefixes. Each prefix
can optionally take its prefix length after "/". IPv6 prefixes
supplied via router advertisements in the list are allowed. Note that if
PrefixAllowList= is configured then
PrefixDenyList= is ignored.
Added in version 248.
RouteDenyList=
A whitespace-separated list of IPv6 route prefixes. Each
prefix can optionally take its prefix length after "/". IPv6 route
prefixes supplied via router advertisements in the list are ignored.
Added in version 248.
RouteAllowList=
A whitespace-separated list of IPv6 route prefixes. Each
prefix can optionally take its prefix length after "/". IPv6 route
prefixes supplied via router advertisements in the list are allowed. Note that
if
RouteAllowList= is configured then
RouteDenyList= is ignored.
Added in version 248.
DHCPv6Client=
Takes a boolean, or the special value "always".
When true, the DHCPv6 client will be started in "solicit" mode if
the RA has the "managed" flag or "information-request"
mode if the RA lacks the "managed" flag but has the "other
configuration" flag. If set to "always", the DHCPv6 client will
be started in "solicit" mode when an RA is received, even if neither
the "managed" nor the "other configuration" flag is set in
the RA. This will be ignored when
WithoutRA= in the [DHCPv6] section is
enabled, or
UplinkInterface=:self in the [DHCPPrefixDelegation] section
is specified. Defaults to true.
Added in version 246.
NetLabel=
This applies the NetLabel for the addresses received with
RA, like
NetLabel= in [Address] section applies it to statically
configured addresses. See
NetLabel= in [Address] section for more
details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with RA, like
NFTSet= in [Address] section applies it to
static configuration. See
NFTSet= in [Address] section for more
details. For "address" or "prefix" source types, the type
of the element used in the NFT filter must be "ipv6_addr".
Added in version 255.
[DHCPSERVER] SECTION OPTIONS¶
The [DHCPServer] section contains settings for the DHCP server, if
enabled via the DHCPServer= option described above:
ServerAddress=
Specifies the server address for the DHCP server. Takes
an IPv4 address with prefix length separated with a slash, e.g.
"192.168.0.1/24". Defaults to unset, and one of static IPv4
addresses configured in [Network] or [Address] section will be automatically
selected. This setting may be useful when the interface on which the DHCP
server is running has multiple static IPv4 addresses.
This implies Address= in [Network] or [Address] section
with the same address and prefix length. That is,
[Network]
DHCPServer=yes
Address=192.168.0.1/24
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
or
[Network]
DHCPServer=yes
[Address]
Address=192.168.0.1/24
[Address]
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
are equivalent to the following:
[Network]
DHCPServer=yes
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
Since version 255, like the Address= setting in [Network]
or [Address] section, this also supports a null address, e.g.
"0.0.0.0/24", and an unused address will be automatically
selected. For more details about the automatic address selection, see
Address= setting in [Network] section in the above.
Added in version 249.
PoolOffset=, PoolSize=
Configures the pool of addresses to hand out. The pool is
a contiguous sequence of IP addresses in the subnet configured for the server
address, which does not include the subnet nor the broadcast address.
PoolOffset= takes the offset of the pool from the start of subnet, or
zero to use the default value.
PoolSize= takes the number of IP
addresses in the pool or zero to use the default value. By default, the pool
starts at the first address after the subnet address and takes up the rest of
the subnet, excluding the broadcast address. If the pool includes the server
address (the default), this is reserved and not handed out to clients.
Added in version 226.
DefaultLeaseTimeSec=, MaxLeaseTimeSec=
Control the default and maximum DHCP lease time to pass
to clients. These settings take time values in seconds or another common time
unit, depending on the suffix. The default lease time is used for clients that
did not ask for a specific lease time. If a client asks for a lease time
longer than the maximum lease time, it is automatically shortened to the
specified time. The default lease time defaults to 1h, the maximum lease time
to 12h. Shorter lease times are beneficial if the configuration data in DHCP
leases changes frequently and clients shall learn the new settings with
shorter latencies. Longer lease times reduce the generated DHCP network
traffic.
Added in version 226.
UplinkInterface=
Specifies the name or the index of the uplink interface,
or one of the special values ":none" and ":auto". When
emitting DNS, NTP, or SIP servers is enabled but no servers are specified, the
servers configured in the uplink interface will be emitted. When
":auto", the link which has a default gateway with the highest
priority will be automatically selected. When ":none", no uplink
interface will be selected. Defaults to ":auto".
Added in version 249.
EmitDNS=, DNS=
EmitDNS= takes a boolean. Configures whether the
DHCP leases handed out to clients shall contain DNS server information.
Defaults to "yes". The DNS servers to pass to clients may be
configured with the
DNS= option, which takes a list of IPv4 addresses,
or special value "_server_address" which will be converted to the
address used by the DHCP server.
If the EmitDNS= option is enabled but no servers
configured, the servers are automatically propagated from an
"uplink" interface that has appropriate servers set. The
"uplink" interface is determined by the default route of the
system with the highest priority. Note that this information is acquired at
the time the lease is handed out, and does not take uplink interfaces into
account that acquire DNS server information at a later point. If no suitable
uplink interface is found the DNS server data from /etc/resolv.conf is used.
Also, note that the leases are not refreshed if the uplink network
configuration changes. To ensure clients regularly acquire the most current
uplink DNS server information, it is thus advisable to shorten the DHCP
lease time via MaxLeaseTimeSec= described above.
This setting can be specified multiple times. If an empty string
is specified, then all DNS servers specified earlier are cleared.
Added in version 226.
EmitNTP=, NTP=, EmitSIP=, SIP=,
EmitPOP3=, POP3=, EmitSMTP=, SMTP=,
EmitLPR=, LPR=
Similar to the
EmitDNS= and
DNS= settings
described above, these settings configure whether and what server information
for the indicate protocol shall be emitted as part of the DHCP lease. The same
syntax, propagation semantics and defaults apply as for
EmitDNS= and
DNS=.
Added in version 226.
EmitRouter=, Router=
The
EmitRouter= setting takes a boolean value, and
configures whether the DHCP lease should contain the router option. The
Router= setting takes an IPv4 address, and configures the router
address to be emitted. When the
Router= setting is not specified, then
the server address will be used for the router option. When the
EmitRouter= setting is disabled, the
Router= setting will be
ignored. The
EmitRouter= setting defaults to true, and the
Router= setting defaults to unset.
Added in version 230.
EmitTimezone=, Timezone=
Takes a boolean. Configures whether the DHCP leases
handed out to clients shall contain timezone information. Defaults to
"yes". The
Timezone= setting takes a timezone string (such as
"Europe/Berlin" or "UTC") to pass to clients. If no
explicit timezone is set, the system timezone of the local host is propagated,
as determined by the /etc/localtime symlink.
Added in version 226.
BootServerAddress=
Takes an IPv4 address of the boot server used by e.g. PXE
boot systems. When specified, this address is sent in the
siaddr field
of the DHCP message header. See
RFC 2131[39] for more details. Defaults
to unset.
Added in version 251.
BootServerName=
Takes a name of the boot server used by e.g. PXE boot
systems. When specified, this name is sent in the DHCP option 66 ("TFTP
server name"). See
RFC 2132[40] for more details. Defaults to
unset.
Note that typically setting one of BootServerName= or
BootServerAddress= is sufficient, but both can be set too, if
desired.
Added in version 251.
BootFilename=
Takes a path or URL to a file loaded by e.g. a PXE boot
loader. When specified, this path is sent in the DHCP option 67
("Bootfile name"). See
RFC 2132[40] for more details.
Defaults to unset.
Added in version 251.
IPv6OnlyPreferredSec=
Takes a timespan. Controls the
RFC 8925[33]
IPv6-Only Preferred option. Specifies the DHCPv4 option to indicate that a
host supports an IPv6-only mode and is willing to forgo obtaining an IPv4
address if the network provides IPv6 connectivity. Defaults to unset, and not
send the option. The minimum allowed value is 300 seconds.
Added in version 255.
SendOption=
Send a raw option with value via DHCPv4 server. Takes a
DHCP option number, data type and data
("
option:
type:
value"). The option number is an
integer in the range 1...254. The type takes one of "uint8",
"uint16", "uint32", "ipv4address",
"ipv6address", or "string". Special characters in the data
string may be escaped using
C-style escapes[28]. This setting can be
specified multiple times. If an empty string is specified, then all options
specified earlier are cleared. Defaults to unset.
Added in version 244.
SendVendorOption=
Send a vendor option with value via DHCPv4 server. Takes
a DHCP option number, data type and data
("
option:
type:
value"). The option number is an
integer in the range 1...254. The type takes one of "uint8",
"uint16", "uint32", "ipv4address", or
"string". Special characters in the data string may be escaped using
C-style escapes[28]. This setting can be specified multiple times. If
an empty string is specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 246.
BindToInterface=
Takes a boolean value. When "yes", DHCP server
socket will be bound to its network interface and all socket communication
will be restricted to this interface. Defaults to "yes", except if
RelayTarget= is used (see below), in which case it defaults to
"no".
Added in version 249.
RelayTarget=
Takes an IPv4 address, which must be in the format
described in
inet_pton(3). Turns this DHCP server into a DHCP relay
agent. See
RFC 1542[41]. The address is the address of DHCP server or
another relay agent to forward DHCP messages to and from.
Added in version 249.
RelayAgentCircuitId=
Specifies value for Agent Circuit ID suboption of Relay
Agent Information option. Takes a string, which must be in the format
"string:
value", where "
value" should be
replaced with the value of the suboption. Defaults to unset (means no Agent
Circuit ID suboption is generated). Ignored if
RelayTarget= is not
specified.
Added in version 249.
RelayAgentRemoteId=
Specifies value for Agent Remote ID suboption of Relay
Agent Information option. Takes a string, which must be in the format
"string:
value", where "
value" should be
replaced with the value of the suboption. Defaults to unset (means no Agent
Remote ID suboption is generated). Ignored if
RelayTarget= is not
specified.
Added in version 249.
RapidCommit=
Takes a boolean. When true, the server supports
RFC
4039[42]. When a client sends a DHCPDISCOVER message with the Rapid Commit
option to the server, then the server will reply with a DHCPACK message to the
client, instead of DHCPOFFER. Defaults to true.
Added in version 255.
PersistLeases=
Takes a boolean. When true, the DHCP server will load and
save leases in the persistent storage. When false, the DHCP server will
neither load nor save leases in the persistent storage. Hence, bound leases
will be lost when the interface is reconfigured e.g. by
networkctl
reconfigure, or
systemd-networkd.service(8) is restarted. That may
cause address conflict on the network. So, please take an extra care when
disable this setting. When unspecified, the value specified in the same
setting in
networkd.conf(5), which defaults to "yes", will be
used.
Added in version 256.
[DHCPSERVERSTATICLEASE] SECTION OPTIONS¶
The "[DHCPServerStaticLease]" section configures a
static DHCP lease to assign a fixed IPv4 address to a specific device based
on its MAC address. This section can be specified multiple times.
MACAddress=
The hardware address of a device to match. This key is
mandatory.
Added in version 249.
Address=
The IPv4 address that should be assigned to the device
that was matched with
MACAddress=. This key is mandatory.
Added in version 249.
[IPV6SENDRA] SECTION OPTIONS¶
The [IPv6SendRA] section contains settings for sending IPv6 Router
Advertisements and whether to act as a router, if enabled via the
IPv6SendRA= option described above. IPv6 network prefixes or routes
are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
Managed=, OtherInformation=
Takes a boolean. Controls whether a DHCPv6 server is used
to acquire IPv6 addresses on the network link when
Managed= is set to
"true" or if only additional network information can be obtained via
DHCPv6 for the network link when
OtherInformation= is set to
"true". Both settings default to "false", which means that
a DHCPv6 server is not being used.
Added in version 235.
RouterLifetimeSec=
Takes a timespan. Configures the IPv6 router lifetime in
seconds. The value must be 0 seconds, or between 4 seconds and 9000 seconds.
When set to 0, the host is not acting as a router. Defaults to 1800 seconds
(30 minutes).
Added in version 235.
ReachableTimeSec=
Configures the time, used in the Neighbor Unreachability
Detection algorithm, for which clients can assume a neighbor is reachable
after having received a reachability confirmation. Takes a time span in the
range 0...4294967295 ms. When 0, clients will handle it as if the value was
not specified. Defaults to 0.
Added in version 256.
RetransmitSec=
Configures the time, used in the Neighbor Unreachability
Detection algorithm, for which clients can use as retransmit time on address
resolution and the Neighbor Unreachability Detection algorithm. Takes a time
span in the range 0...4294967295 ms. When 0, clients will handle it as if the
value wasn't specified. Defaults to 0.
Added in version 255.
RouterPreference=
Configures IPv6 router preference if
RouterLifetimeSec= is non-zero. Valid values are "high",
"medium" and "low", with "normal" and
"default" added as synonyms for "medium" just to make
configuration easier. See
RFC 4191[24] for details. Defaults to
"medium".
Added in version 235.
HopLimit=
Configures hop limit. Takes an integer in the range
0...255. See also
IPv6HopLimit=.
Added in version 255.
UplinkInterface=
Specifies the name or the index of the uplink interface,
or one of the special values ":none" and ":auto". When
emitting DNS servers or search domains is enabled but no servers are
specified, the servers configured in the uplink interface will be emitted.
When ":auto", the value specified to the same setting in the
[DHCPPrefixDelegation] section will be used if
DHCPPrefixDelegation= is
enabled, otherwise the link which has a default gateway with the highest
priority will be automatically selected. When ":none", no uplink
interface will be selected. Defaults to ":auto".
Added in version 250.
EmitDNS=, DNS=
DNS= specifies a list of recursive DNS server IPv6
addresses that are distributed via Router Advertisement messages when
EmitDNS= is true.
DNS= also takes special value
"_link_local"; in that case the IPv6 link-local address is
distributed. If
DNS= is empty, DNS servers are read from the [Network]
section. If the [Network] section does not contain any DNS servers either, DNS
servers from the uplink interface specified in
UplinkInterface= will be
used. When
EmitDNS= is false, no DNS server information is sent in
Router Advertisement messages.
EmitDNS= defaults to true.
Added in version 235.
EmitDomains=, Domains=
A list of DNS search domains distributed via Router
Advertisement messages when
EmitDomains= is true. If
Domains= is
empty, DNS search domains are read from the [Network] section. If the
[Network] section does not contain any DNS search domains either, DNS search
domains from the uplink interface specified in
UplinkInterface= will be
used. When
EmitDomains= is false, no DNS search domain information is
sent in Router Advertisement messages.
EmitDomains= defaults to true.
Added in version 235.
DNSLifetimeSec=
Lifetime in seconds for the DNS server addresses listed
in
DNS= and search domains listed in
Domains=. Defaults to 3600
seconds (one hour).
Added in version 235.
HomeAgent=
Takes a boolean. Specifies that IPv6 router
advertisements indicate to hosts that the router acts as a Home Agent and
includes a Home Agent option. Defaults to false. See
RFC 6275[13] for
further details.
Added in version 255.
HomeAgentLifetimeSec=
Takes a timespan. Specifies the lifetime of the Home
Agent. An integer, the default unit is seconds, in the range 1...65535.
Defaults to the value set to
RouterLifetimeSec=.
Added in version 255.
HomeAgentPreference=
Configures IPv6 Home Agent preference. Takes an integer
in the range 0...65535. Defaults to 0.
Added in version 255.
[IPV6PREFIX] SECTION OPTIONS¶
One or more [IPv6Prefix] sections contain the IPv6 prefixes that
are announced via Router Advertisements. See RFC 4861[43] for further
details.
AddressAutoconfiguration=, OnLink=
Takes a boolean to specify whether IPv6 addresses can be
autoconfigured with this prefix and whether the prefix can be used for onlink
determination. Both settings default to "true" in order to ease
configuration.
Added in version 235.
Prefix=
The IPv6 prefix that is to be distributed to hosts.
Similarly to configuring static IPv6 addresses, the setting is configured as
an IPv6 prefix and its prefix length, separated by a "/" character.
Use multiple [IPv6Prefix] sections to configure multiple IPv6 prefixes since
prefix lifetimes, address autoconfiguration and onlink status may differ from
one prefix to another.
Added in version 235.
PreferredLifetimeSec=, ValidLifetimeSec=
Preferred and valid lifetimes for the prefix measured in
seconds.
PreferredLifetimeSec= defaults to 1800 seconds (30 minutes)
and
ValidLifetimeSec= defaults to 3600 seconds (one hour).
Added in version 235.
Assign=
Takes a boolean. When true, adds an address from the
prefix. Default to false.
Added in version 246.
Token=
Specifies an optional address generation mode for
assigning an address in each prefix. This accepts the same syntax as
Token= in the [IPv6AcceptRA] section. If
Assign= is set to
false, then this setting will be ignored. Defaults to unset, which means the
EUI-64 algorithm will be used.
Added in version 250.
RouteMetric=
The metric of the prefix route. Takes an unsigned integer
in the range 0...4294967295. When unset or set to 0, the kernel's default
value is used. This setting is ignored when
Assign= is false.
Added in version 249.
[IPV6ROUTEPREFIX] SECTION OPTIONS¶
One or more [IPv6RoutePrefix] sections contain the IPv6 prefix
routes that are announced via Router Advertisements. See RFC 4191[24]
for further details.
Route=
The IPv6 route that is to be distributed to hosts.
Similarly to configuring static IPv6 routes, the setting is configured as an
IPv6 prefix routes and its prefix route length, separated by a "/"
character. Use multiple [IPv6RoutePrefix] sections to configure multiple IPv6
prefix routes.
Added in version 244.
LifetimeSec=
Lifetime for the route prefix measured in seconds.
LifetimeSec= defaults to 3600 seconds (one hour).
Added in version 244.
[IPV6PREF64PREFIX] SECTION OPTIONS¶
One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64
(or NAT64) prefixes that are announced via Router Advertisements. See RFC
8781[38] for further details.
Prefix=
The IPv6 PREF64 (or NAT64) prefix that is to be
distributed to hosts. The setting holds an IPv6 prefix that should be set up
for NAT64 translation (PLAT) to allow 464XLAT on the network segment. Use
multiple [IPv6PREF64Prefix] sections to configure multiple IPv6 prefixes since
prefix lifetime may differ from one prefix to another. The prefix is an
address with a prefix length, separated by a slash "/" character.
Valid NAT64 prefix length are 96, 64, 56, 48, 40, and 32 bits.
Added in version 255.
LifetimeSec=
Lifetime for the prefix measured in seconds. Should be
greater than or equal to
RouterLifetimeSec=.
LifetimeSec=
defaults to 1800 seconds.
Added in version 255.
[BRIDGE] SECTION OPTIONS¶
The [Bridge] section accepts the following keys:
UnicastFlood=
Takes a boolean. Controls whether the bridge should flood
traffic for which an FDB entry is missing and the destination is unknown
through this port. When unset, the kernel's default will be used.
Added in version 223.
MulticastFlood=
Takes a boolean. Controls whether the bridge should flood
traffic for which an MDB entry is missing and the destination is unknown
through this port. When unset, the kernel's default will be used.
Added in version 242.
MulticastToUnicast=
Takes a boolean. Multicast to unicast works on top of the
multicast snooping feature of the bridge. Which means unicast copies are only
delivered to hosts which are interested in it. When unset, the kernel's
default will be used.
Added in version 240.
NeighborSuppression=
Takes a boolean. Configures whether ARP and ND neighbor
suppression is enabled for this port. When unset, the kernel's default will be
used.
Added in version 242.
Learning=
Takes a boolean. Configures whether MAC address learning
is enabled for this port. When unset, the kernel's default will be used.
Added in version 242.
HairPin=
Takes a boolean. Configures whether traffic may be sent
back out of the port on which it was received. When this flag is false, then
the bridge will not forward traffic back out of the receiving port. When
unset, the kernel's default will be used.
Added in version 223.
Isolated=
Takes a boolean. Configures whether this port is isolated
or not. Within a bridge, isolated ports can only communicate with non-isolated
ports. When set to true, this port can only communicate with other ports whose
Isolated setting is false. When set to false, this port can communicate with
any other ports. When unset, the kernel's default will be used.
Added in version 251.
UseBPDU=
Takes a boolean. Configures whether STP Bridge Protocol
Data Units will be processed by the bridge port. When unset, the kernel's
default will be used.
Added in version 223.
FastLeave=
Takes a boolean. This flag allows the bridge to
immediately stop multicast traffic on a port that receives an IGMP Leave
message. It is only used with IGMP snooping if enabled on the bridge. When
unset, the kernel's default will be used.
Added in version 223.
AllowPortToBeRoot=
Takes a boolean. Configures whether a given port is
allowed to become a root port. Only used when STP is enabled on the bridge.
When unset, the kernel's default will be used.
Added in version 223.
ProxyARP=
Takes a boolean. Configures whether proxy ARP to be
enabled on this port. When unset, the kernel's default will be used.
Added in version 243.
ProxyARPWiFi=
Takes a boolean. Configures whether proxy ARP to be
enabled on this port which meets extended requirements by IEEE 802.11 and
Hotspot 2.0 specifications. When unset, the kernel's default will be used.
Added in version 243.
MulticastRouter=
Configures this port for having multicast routers
attached. A port with a multicast router will receive all multicast traffic.
Takes one of "no" to disable multicast routers on this port,
"query" to let the system detect the presence of routers,
"permanent" to permanently enable multicast traffic forwarding on
this port, or "temporary" to enable multicast routers temporarily on
this port, not depending on incoming queries. When unset, the kernel's default
will be used.
Added in version 243.
Cost=
Sets the "cost" of sending packets of this
interface. Each port in a bridge may have a different speed and the cost is
used to decide which link to use. Faster interfaces should have lower costs.
It is an integer value between 1 and 65535.
Added in version 218.
Priority=
Sets the "priority" of sending packets on this
interface. Each port in a bridge may have a different priority which is used
to decide which link to use. Lower value means higher priority. It is an
integer value between 0 to 63.
systemd-networkd does not set any
default, meaning the kernel default value of 32 is used.
Added in version 234.
[BRIDGEFDB] SECTION OPTIONS¶
The [BridgeFDB] section manages the forwarding database table of a
port and accepts the following keys. Specify several [BridgeFDB] sections to
configure several static MAC table entries.
MACAddress=
As in the [Network] section. This key is mandatory.
Added in version 219.
Destination=
Takes an IP address of the destination VXLAN tunnel
endpoint.
Added in version 243.
VLANId=
The VLAN ID for the new static MAC table entry. If
omitted, no VLAN ID information is appended to the new static MAC table entry.
Added in version 219.
VNI=
The VXLAN Network Identifier (or VXLAN Segment ID) to use
to connect to the remote VXLAN tunnel endpoint. Takes a number in the range
1...16777215. Defaults to unset.
Added in version 243.
AssociatedWith=
Specifies where the address is associated with. Takes one
of "use", "self", "master" or
"router". "use" means the address is in use. User space
can use this option to indicate to the kernel that the fdb entry is in use.
"self" means the address is associated with the port drivers fdb.
Usually hardware. "master" means the address is associated with
master devices fdb. "router" means the destination address is
associated with a router. Note that it is valid if the referenced device is a
VXLAN type device and has route shortcircuit enabled. Defaults to
"self".
Added in version 243.
OutgoingInterface=
Specifies the name or index of the outgoing interface for
the VXLAN device driver to reach the remote VXLAN tunnel endpoint. Defaults to
unset.
Added in version 249.
[BRIDGEMDB] SECTION OPTIONS¶
The [BridgeMDB] section manages the multicast membership entries
forwarding database table of a port and accepts the following keys. Specify
several [BridgeMDB] sections to configure several permanent multicast
membership entries.
MulticastGroupAddress=
Specifies the IPv4, IPv6, or L2 MAC multicast group
address to add. This setting is mandatory.
Added in version 247.
VLANId=
The VLAN ID for the new entry. Valid ranges are 0 (no
VLAN) to 4094. Optional, defaults to 0.
Added in version 247.
[LLDP] SECTION OPTIONS¶
The [LLDP] section manages the Link Layer Discovery Protocol
(LLDP) and accepts the following keys:
MUDURL=
When configured, the specified Manufacturer Usage
Descriptions (MUD) URL will be sent in LLDP packets. The syntax and semantics
are the same as for
MUDURL= in the [DHCPv4] section described above.
The MUD URLs received via LLDP packets are saved and can be read
using the sd_lldp_neighbor_get_mud_url() function.
Added in version 246.
[CAN] SECTION OPTIONS¶
The [CAN] section manages the Controller Area Network (CAN bus)
and accepts the following keys:
BitRate=
The bitrate of CAN device in bits per second. The usual
SI prefixes (K, M) with the base of 1000 can be used here. Takes a number in
the range 1...4294967295.
Added in version 239.
SamplePoint=
Optional sample point in percent with one decimal (e.g.
"75%", "87.5%") or permille (e.g.
"875‰"). This will be ignored when
BitRate= is
unspecified.
Added in version 239.
TimeQuantaNSec=, PropagationSegment=,
PhaseBufferSegment1=, PhaseBufferSegment2=,
SyncJumpWidth=
Specifies the time quanta, propagation segment, phase
buffer segment 1 and 2, and the synchronization jump width, which allow one to
define the CAN bit-timing in a hardware independent format as proposed by the
Bosch CAN 2.0 Specification.
TimeQuantaNSec= takes a timespan in
nanoseconds.
PropagationSegment=,
PhaseBufferSegment1=,
PhaseBufferSegment2=, and
SyncJumpWidth= take number of time
quantum specified in
TimeQuantaNSec= and must be an unsigned integer in
the range 0...4294967295. These settings except for
SyncJumpWidth= will
be ignored when
BitRate= is specified.
Added in version 250.
DataBitRate=, DataSamplePoint=
The bitrate and sample point for the data phase, if
CAN-FD is used. These settings are analogous to the
BitRate= and
SamplePoint= keys.
Added in version 246.
DataTimeQuantaNSec=, DataPropagationSegment=,
DataPhaseBufferSegment1=, DataPhaseBufferSegment2=,
DataSyncJumpWidth=
Specifies the time quanta, propagation segment, phase
buffer segment 1 and 2, and the synchronization jump width for the data phase,
if CAN-FD is used. These settings are analogous to the
TimeQuantaNSec=
or related settings.
Added in version 250.
FDMode=
Takes a boolean. When "yes", CAN-FD mode is
enabled for the interface. Note, that a bitrate and optional sample point
should also be set for the CAN-FD data phase using the
DataBitRate= and
DataSamplePoint= keys, or
DataTimeQuanta= and related settings.
Added in version 246.
FDNonISO=
Takes a boolean. When "yes", non-ISO CAN-FD
mode is enabled for the interface. When unset, the kernel's default will be
used.
Added in version 246.
RestartSec=
Automatic restart delay time. If set to a non-zero value,
a restart of the CAN controller will be triggered automatically in case of a
bus-off condition after the specified delay time. Subsecond delays can be
specified using decimals (e.g. "0.1s") or a "ms" or
"us" postfix. Using "infinity" or "0" will turn
the automatic restart off. By default, automatic restart is disabled.
Added in version 239.
Termination=
Takes a boolean or a termination resistor value in ohm in
the range 0...65535. When "yes", the termination resistor is set to
120 ohm. When "no" or "0" is set, the termination resistor
is disabled. When unset, the kernel's default will be used.
Added in version 246.
TripleSampling=
Takes a boolean. When "yes", three samples
(instead of one) are used to determine the value of a received bit by majority
rule. When unset, the kernel's default will be used.
Added in version 242.
BusErrorReporting=
Takes a boolean. When "yes", reporting of CAN
bus errors is activated (those include single bit, frame format, and bit
stuffing errors, unable to send dominant bit, unable to send recessive bit,
bus overload, active error announcement, error occurred on transmission). When
unset, the kernel's default will be used. Note: in case of a CAN bus with a
single CAN device, sending a CAN frame may result in a huge number of CAN bus
errors.
Added in version 248.
ListenOnly=
Takes a boolean. When "yes", listen-only mode
is enabled. When the interface is in listen-only mode, the interface neither
transmit CAN frames nor send ACK bit. Listen-only mode is important to debug
CAN networks without interfering with the communication or acknowledge the CAN
frame. When unset, the kernel's default will be used.
Added in version 246.
Loopback=
Takes a boolean. When "yes", loopback mode is
enabled. When the loopback mode is enabled, the interface treats messages
transmitted by itself as received messages. The loopback mode is important to
debug CAN networks. When unset, the kernel's default will be used.
Added in version 250.
OneShot=
Takes a boolean. When "yes", one-shot mode is
enabled. When unset, the kernel's default will be used.
Added in version 250.
PresumeAck=
Takes a boolean. When "yes", the interface will
ignore missing CAN ACKs. When unset, the kernel's default will be used.
Added in version 250.
ClassicDataLengthCode=
Takes a boolean. When "yes", the interface will
handle the 4bit data length code (DLC). When unset, the kernel's default will
be used.
Added in version 250.
[IPOIB] SECTION OPTIONS¶
The [IPoIB] section manages the IP over Infiniband and accepts the
following keys:
Mode=
Takes one of the special values "datagram" or
"connected". Defaults to unset, and the kernel's default is used.
When "datagram", the Infiniband unreliable datagram (UD)
transport is used, and so the interface MTU is equal to the IB L2 MTU minus
the IPoIB encapsulation header (4 bytes). For example, in a typical IB
fabric with a 2K MTU, the IPoIB MTU will be 2048 - 4 = 2044 bytes.
When "connected", the Infiniband reliable connected (RC)
transport is used. Connected mode takes advantage of the connected nature of
the IB transport and allows an MTU up to the maximal IP packet size of 64K,
which reduces the number of IP packets needed for handling large UDP
datagrams, TCP segments, etc and increases the performance for large
messages.
Added in version 250.
IgnoreUserspaceMulticastGroup=
Takes an boolean value. When true, the kernel ignores
multicast groups handled by userspace. Defaults to unset, and the kernel's
default is used.
Added in version 250.
[QDISC] SECTION OPTIONS¶
The [QDisc] section manages the traffic control queueing
discipline (qdisc).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes
one of "clsact" or "ingress". This is mandatory.
Added in version 244.
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[NETWORKEMULATOR] SECTION OPTIONS¶
The [NetworkEmulator] section manages the queueing discipline
(qdisc) of the network emulator. It can be used to configure the kernel
packet scheduler and simulate packet delay and loss for UDP or TCP
applications, or limit the bandwidth usage of a particular service to
simulate internet connections.
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
DelaySec=
Specifies the fixed amount of delay to be added to all
packets going out of the interface. Defaults to unset.
Added in version 245.
DelayJitterSec=
Specifies the chosen delay to be added to the packets
outgoing to the network interface. Defaults to unset.
Added in version 245.
PacketLimit=
Specifies the maximum number of packets the qdisc may
hold queued at a time. An unsigned integer in the range 0...4294967294.
Defaults to 1000.
Added in version 245.
LossRate=
Specifies an independent loss probability to be added to
the packets outgoing from the network interface. Takes a percentage value,
suffixed with "%". Defaults to unset.
Added in version 245.
DuplicateRate=
Specifies that the chosen percent of packets is
duplicated before queuing them. Takes a percentage value, suffixed with
"%". Defaults to unset.
Added in version 245.
[TOKENBUCKETFILTER] SECTION OPTIONS¶
The [TokenBucketFilter] section manages the queueing discipline
(qdisc) of token bucket filter (tbf).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
LatencySec=
Specifies the latency parameter, which specifies the
maximum amount of time a packet can sit in the Token Bucket Filter (TBF).
Defaults to unset.
Added in version 245.
LimitBytes=
Takes the number of bytes that can be queued waiting for
tokens to become available. When the size is suffixed with K, M, or G, it is
parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset.
Added in version 246.
BurstBytes=
Specifies the size of the bucket. This is the maximum
amount of bytes that tokens can be available for instantaneous transfer. When
the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to unset.
Added in version 246.
Rate=
Specifies the device specific bandwidth. When suffixed
with K, M, or G, the specified bandwidth is parsed as Kilobits, Megabits, or
Gigabits, respectively, to the base of 1000. Defaults to unset.
Added in version 245.
MPUBytes=
The Minimum Packet Unit (MPU) determines the minimal
token usage (specified in bytes) for a packet. When suffixed with K, M, or G,
the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
respectively, to the base of 1024. Defaults to zero.
Added in version 245.
PeakRate=
Takes the maximum depletion rate of the bucket. When
suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits,
or Gigabits, respectively, to the base of 1000. Defaults to unset.
Added in version 245.
MTUBytes=
Specifies the size of the peakrate bucket. When suffixed
with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to unset.
Added in version 245.
[PIE] SECTION OPTIONS¶
The [PIE] section manages the queueing discipline (qdisc) of
Proportional Integral controller-Enhanced (PIE).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are dropped. An unsigned
integer in the range 1...4294967294. Defaults to unset and kernel's default is
used.
Added in version 246.
[FLOWQUEUEPIE] SECTION OPTIONS¶
The "[FlowQueuePIE]" section manages the queueing
discipline (qdisc) of Flow Queue Proportional Integral controller-Enhanced
(fq_pie).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are dropped. An unsigned
integer ranges 1 to 4294967294. Defaults to unset and kernel's default is
used.
Added in version 247.
[STOCHASTICFAIRBLUE] SECTION OPTIONS¶
The [StochasticFairBlue] section manages the queueing discipline
(qdisc) of stochastic fair blue (sfb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are dropped. An unsigned
integer in the range 0...4294967294. Defaults to unset and kernel's default is
used.
Added in version 246.
[STOCHASTICFAIRNESSQUEUEING] SECTION OPTIONS¶
The [StochasticFairnessQueueing] section manages the queueing
discipline (qdisc) of stochastic fairness queueing (sfq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PerturbPeriodSec=
Specifies the interval in seconds for queue algorithm
perturbation. Defaults to unset.
Added in version 245.
[BFIFO] SECTION OPTIONS¶
The [BFIFO] section manages the queueing discipline (qdisc) of
Byte limited Packet First In First Out (bfifo).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
LimitBytes=
Specifies the hard limit in bytes on the FIFO buffer
size. The size limit prevents overflow in case the kernel is unable to dequeue
packets as quickly as it receives them. When this limit is reached, incoming
packets are dropped. When suffixed with K, M, or G, the specified size is
parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel default is used.
Added in version 246.
[PFIFO] SECTION OPTIONS¶
The [PFIFO] section manages the queueing discipline (qdisc) of
Packet First In First Out (pfifo).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the number of packets in the
FIFO queue. The size limit prevents overflow in case the kernel is unable to
dequeue packets as quickly as it receives them. When this limit is reached,
incoming packets are dropped. An unsigned integer in the range 0...4294967294.
Defaults to unset and kernel's default is used.
Added in version 246.
[PFIFOHEADDROP] SECTION OPTIONS¶
The [PFIFOHeadDrop] section manages the queueing discipline
(qdisc) of Packet First In First Out Head Drop (pfifo_head_drop).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
As in [PFIFO] section.
Added in version 246.
[PFIFOFAST] SECTION OPTIONS¶
The [PFIFOFast] section manages the queueing discipline (qdisc) of
Packet First In First Out Fast (pfifo_fast).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[CAKE] SECTION OPTIONS¶
The [CAKE] section manages the queueing discipline (qdisc) of
Common Applications Kept Enhanced (CAKE).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Bandwidth=
Specifies the shaper bandwidth. When suffixed with K, M,
or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
respectively, to the base of 1000. Defaults to unset and kernel's default is
used.
Added in version 246.
AutoRateIngress=
Takes a boolean value. Enables automatic capacity
estimation based on traffic arriving at this qdisc. This is most likely to be
useful with cellular links, which tend to change quality randomly. If this
setting is enabled, the
Bandwidth= setting is used as an initial
estimate. Defaults to unset, and the kernel's default is used.
Added in version 250.
OverheadBytes=
Specifies that bytes to be addeded to the size of each
packet. Bytes may be negative. Takes an integer in the range -64...256.
Defaults to unset and kernel's default is used.
Added in version 246.
MPUBytes=
Rounds each packet (including overhead) up to the
specified bytes. Takes an integer in the range 1...256. Defaults to unset and
kernel's default is used.
Added in version 250.
CompensationMode=
Takes one of "none", "atm", or
"ptm". Specifies the compensation mode for overhead calculation.
When "none", no compensation is taken into account. When
"atm", enables the compensation for ATM cell framing, which is
normally found on ADSL links. When "ptm", enables the compensation
for PTM encoding, which is normally found on VDSL2 links and uses a 64b/65b
encoding scheme. Defaults to unset and the kernel's default is used.
Added in version 250.
UseRawPacketSize=
Takes a boolean value. When true, the packet size
reported by the Linux kernel will be used, instead of the underlying IP packet
size. Defaults to unset, and the kernel's default is used.
Added in version 250.
FlowIsolationMode=
CAKE places packets from different flows into different
queues, then packets from each queue are delivered fairly. This specifies
whether the fairness is based on source address, destination address,
individual flows, or any combination of those. The available values are:
none
The flow isolation is disabled, and all traffic passes
through a single queue.
Added in version 250.
src-host
Flows are defined only by source address. Equivalent to
the "srchost" option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
dst-host
Flows are defined only by destination address. Equivalent
to the "dsthost" option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
hosts
Flows are defined by source-destination host pairs.
Equivalent to the same option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
flows
Flows are defined by the entire 5-tuple of source
address, destination address, transport protocol, source port and destination
port. Equivalent to the same option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
dual-src-host
Flows are defined by the 5-tuple (see "flows"
in the above), and fairness is applied first over source addresses, then over
individual flows. Equivalent to the "dual-srchost" option for
tc
qdisc command. See also
tc-cake(8).
Added in version 250.
dual-dst-host
Flows are defined by the 5-tuple (see "flows"
in the above), and fairness is applied first over destination addresses, then
over individual flows. Equivalent to the "dual-dsthost" option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
triple
Flows are defined by the 5-tuple (see "flows"),
and fairness is applied over source and destination addresses, and also over
individual flows. Equivalent to the "triple-isolate" option for
tc qdisc command. See also
tc-cake(8).
Added in version 250.
Defaults to unset and the kernel's default is used.
Added in version 250.
NAT=
Takes a boolean value. When true, CAKE performs a NAT
lookup before applying flow-isolation rules, to determine the true addresses
and port numbers of the packet, to improve fairness between hosts inside the
NAT. This has no practical effect when
FlowIsolationMode= is
"none" or "flows", or if NAT is performed on a different
host. Defaults to unset, and the kernel's default is used.
Added in version 250.
PriorityQueueingPreset=
CAKE divides traffic into "tins", and each tin
has its own independent set of flow-isolation queues, bandwidth threshold, and
priority. This specifies the preset of tin profiles. The available values are:
besteffort
Disables priority queueing by placing all traffic in one
tin.
Added in version 250.
precedence
Enables priority queueing based on the legacy
interpretation of TOS "Precedence" field. Use of this preset on the
modern Internet is firmly discouraged.
Added in version 250.
diffserv8
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with eight tins: Background Traffic, High
Throughput, Best Effort, Video Streaming, Low Latency Transactions,
Interactive Shell, Minimum Latency, and Network Control.
Added in version 250.
diffserv4
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with four tins: Background Traffic, Best
Effort, Streaming Media, and Latency Sensitive.
Added in version 250.
diffserv3
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with three tins: Background Traffic, Best
Effort, and Latency Sensitive.
Added in version 250.
Defaults to unset, and the kernel's default is used.
Added in version 250.
FirewallMark=
Takes an integer in the range 1...4294967295. When
specified, firewall-mark-based overriding of CAKE's tin selection is enabled.
Defaults to unset, and the kernel's default is used.
Added in version 250.
Wash=
Takes a boolean value. When true, CAKE clears the DSCP
fields, except for ECN bits, of any packet passing through CAKE. Defaults to
unset, and the kernel's default is used.
Added in version 250.
SplitGSO=
Takes a boolean value. When true, CAKE will split General
Segmentation Offload (GSO) super-packets into their on-the-wire components and
dequeue them individually. Defaults to unset, and the kernel's default is
used.
Added in version 250.
RTTSec=
Specifies the RTT for the filter. Takes a timespan.
Typical values are e.g. 100us for extremely high-performance 10GigE+ networks
like datacentre, 1ms for non-WiFi LAN connections, 100ms for typical internet
connections. Defaults to unset, and the kernel's default will be used.
Added in version 253.
AckFilter=
Takes a boolean value, or special value
"aggressive". If enabled, ACKs in each flow are queued and redundant
ACKs to the upstream are dropped. If yes, the filter will always keep at least
two redundant ACKs in the queue, while in "aggressive" mode, it will
filter down to a single ACK. This may improve download throughput on links
with very asymmetrical rate limits. Defaults to unset, and the kernel's
default will be used.
Added in version 253.
[CONTROLLEDDELAY] SECTION OPTIONS¶
The [ControlledDelay] section manages the queueing discipline
(qdisc) of controlled delay (CoDel).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are dropped. An unsigned
integer in the range 0...4294967294. Defaults to unset and kernel's default is
used.
Added in version 245.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and kernel's default is
used.
Added in version 245.
IntervalSec=
Takes a timespan. This is used to ensure that the
measured minimum delay does not become too stale. Defaults to unset and
kernel's default is used.
Added in version 245.
ECN=
Takes a boolean. This can be used to mark packets instead
of dropping them. Defaults to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE). Defaults to unset and
kernel's default is used.
Added in version 245.
[DEFICITROUNDROBINSCHEDULER] SECTION OPTIONS¶
The [DeficitRoundRobinScheduler] section manages the queueing
discipline (qdisc) of Deficit Round Robin Scheduler (DRR).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[DEFICITROUNDROBINSCHEDULERCLASS] SECTION OPTIONS¶
The [DeficitRoundRobinSchedulerClass] section manages the traffic
control class of Deficit Round Robin Scheduler (DRR).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to "root".
ClassId=
Configures the unique identifier of the class. It is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to unset.
QuantumBytes=
Specifies the amount of bytes a flow is allowed to
dequeue before the scheduler moves to the next class. When suffixed with K, M,
or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
respectively, to the base of 1024. Defaults to the MTU of the interface.
Added in version 246.
[ENHANCEDTRANSMISSIONSELECTION] SECTION OPTIONS¶
The [EnhancedTransmissionSelection] section manages the queueing
discipline (qdisc) of Enhanced Transmission Selection (ETS).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Bands=
Specifies the number of bands. An unsigned integer in the
range 1...16. This value has to be at least large enough to cover the strict
bands specified through the
StrictBands= and bandwidth-sharing bands
specified in
QuantumBytes=.
Added in version 246.
StrictBands=
Specifies the number of bands that should be created in
strict mode. An unsigned integer in the range 1...16.
Added in version 246.
QuantumBytes=
Specifies the white-space separated list of quantum used
in band-sharing bands. When suffixed with K, M, or G, the specified size is
parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. This setting can be specified multiple times. If an empty string is
assigned, then the all previous assignments are cleared.
Added in version 246.
PriorityMap=
The priority map maps the priority of a packet to a band.
The argument is a whitespace separated list of numbers. The first number
indicates which band the packets with priority 0 should be put to, the second
is for priority 1, and so on. There can be up to 16 numbers in the list. If
there are fewer, the default band that traffic with one of the unmentioned
priorities goes to is the last one. Each band number must be in the range
0...255. This setting can be specified multiple times. If an empty string is
assigned, then the all previous assignments are cleared.
Added in version 246.
[GENERICRANDOMEARLYDETECTION] SECTION OPTIONS¶
The [GenericRandomEarlyDetection] section manages the queueing
discipline (qdisc) of Generic Random Early Detection (GRED).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
VirtualQueues=
Specifies the number of virtual queues. Takes an integer
in the range 1...16. Defaults to unset and kernel's default is used.
Added in version 246.
DefaultVirtualQueue=
Specifies the number of default virtual queue. This must
be less than
VirtualQueue=. Defaults to unset and kernel's default is
used.
Added in version 246.
GenericRIO=
Takes a boolean. It turns on the RIO-like buffering
scheme. Defaults to unset and kernel's default is used.
Added in version 246.
[FAIRQUEUEINGCONTROLLEDDELAY] SECTION OPTIONS¶
The [FairQueueingControlledDelay] section manages the queueing
discipline (qdisc) of fair queuing controlled delay (FQ-CoDel).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When
this limit is reached, incoming packets are dropped. Defaults to unset and
kernel's default is used.
Added in version 245.
MemoryLimitBytes=
Specifies the limit on the total number of bytes that can
be queued in this FQ-CoDel instance. When suffixed with K, M, or G, the
specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
to the base of 1024. Defaults to unset and kernel's default is used.
Added in version 246.
Flows=
Specifies the number of flows into which the incoming
packets are classified. Defaults to unset and kernel's default is used.
Added in version 245.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and kernel's default is
used.
Added in version 245.
IntervalSec=
Takes a timespan. This is used to ensure that the
measured minimum delay does not become too stale. Defaults to unset and
kernel's default is used.
Added in version 245.
QuantumBytes=
Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan. When suffixed with
K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's
default is used.
Added in version 246.
ECN=
Takes a boolean. This can be used to mark packets instead
of dropping them. Defaults to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE). Defaults to unset and
kernel's default is used.
Added in version 245.
[FAIRQUEUEING] SECTION OPTIONS¶
The [FairQueueing] section manages the queueing discipline (qdisc)
of fair queue traffic policing (FQ).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When
this limit is reached, incoming packets are dropped. Defaults to unset and
kernel's default is used.
Added in version 245.
FlowLimit=
Specifies the hard limit on the maximum number of packets
queued per flow. Defaults to unset and kernel's default is used.
Added in version 245.
QuantumBytes=
Specifies the credit per dequeue RR round, i.e. the
amount of bytes a flow is allowed to dequeue at once. When suffixed with K, M,
or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
respectively, to the base of 1024. Defaults to unset and kernel's default is
used.
Added in version 246.
InitialQuantumBytes=
Specifies the initial sending rate credit, i.e. the
amount of bytes a new flow is allowed to dequeue initially. When suffixed with
K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's
default is used.
Added in version 245.
MaximumRate=
Specifies the maximum sending rate of a flow. When
suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits,
or Gigabits, respectively, to the base of 1000. Defaults to unset and kernel's
default is used.
Added in version 245.
Buckets=
Specifies the size of the hash table used for flow
lookups. Defaults to unset and kernel's default is used.
Added in version 245.
OrphanMask=
Takes an unsigned integer. For packets not owned by a
socket, fq is able to mask a part of hash and reduce number of buckets
associated with the traffic. Defaults to unset and kernel's default is used.
Added in version 245.
Pacing=
Takes a boolean, and enables or disables flow pacing.
Defaults to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE). Defaults to unset and
kernel's default is used.
Added in version 245.
[TRIVIALLINKEQUALIZER] SECTION OPTIONS¶
The [TrivialLinkEqualizer] section manages the queueing discipline
(qdisc) of trivial link equalizer (teql).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Id=
Specifies the interface ID "N" of teql.
Defaults to "0". Note that when teql is used, currently, the module
sch_teql with
max_equalizers=N+1 option must be loaded before
systemd-networkd is started.
Added in version 245.
[HIERARCHYTOKENBUCKET] SECTION OPTIONS¶
The [HierarchyTokenBucket] section manages the queueing discipline
(qdisc) of hierarchy token bucket (htb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
DefaultClass=
Takes the minor id in hexadecimal of the default class.
Unclassified traffic gets sent to the class. Defaults to unset.
Added in version 246.
RateToQuantum=
Takes an unsigned integer. The DRR quantums are
calculated by dividing the value configured in
Rate= by
RateToQuantum=.
Added in version 246.
[HIERARCHYTOKENBUCKETCLASS] SECTION OPTIONS¶
The [HierarchyTokenBucketClass] section manages the traffic
control class of hierarchy token bucket (htb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to "root".
ClassId=
Configures the unique identifier of the class. It is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to unset.
Priority=
Specifies the priority of the class. In the round-robin
process, classes with the lowest priority field are tried for packets first.
Added in version 246.
QuantumBytes=
Specifies how many bytes to serve from leaf at once. When
suffixed with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Added in version 246.
MTUBytes=
Specifies the maximum packet size we create. When
suffixed with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Added in version 246.
OverheadBytes=
Takes an unsigned integer which specifies per-packet size
overhead used in rate computations. When suffixed with K, M, or G, the
specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
to the base of 1024.
Added in version 246.
Rate=
Specifies the maximum rate this class and all its
children are guaranteed. When suffixed with K, M, or G, the specified size is
parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000.
This setting is mandatory.
Added in version 246.
CeilRate=
Specifies the maximum rate at which a class can send, if
its parent has bandwidth to spare. When suffixed with K, M, or G, the
specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to
the base of 1000. When unset, the value specified with
Rate= is used.
Added in version 246.
BufferBytes=
Specifies the maximum bytes burst which can be
accumulated during idle period. When suffixed with K, M, or G, the specified
size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the
base of 1024.
Added in version 246.
CeilBufferBytes=
Specifies the maximum bytes burst for ceil which can be
accumulated during idle period. When suffixed with K, M, or G, the specified
size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the
base of 1024.
Added in version 246.
[CLASSFULMULTIQUEUEING] SECTION OPTIONS¶
The [ClassfulMultiQueueing] section manages the queueing
discipline (qdisc) of Classful Multi Queueing (mq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[BANDMULTIQUEUEING] SECTION OPTIONS¶
The [BandMultiQueueing] section manages the queueing discipline
(qdisc) of Band Multi Queueing (multiq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[HEAVYHITTERFILTER] SECTION OPTIONS¶
The [HeavyHitterFilter] section manages the queueing discipline
(qdisc) of Heavy Hitter Filter (hhf).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are dropped. An unsigned
integer in the range 0...4294967294. Defaults to unset and kernel's default is
used.
Added in version 246.
[QUICKFAIRQUEUEING] SECTION OPTIONS¶
The [QuickFairQueueing] section manages the queueing discipline
(qdisc) of Quick Fair Queueing (QFQ).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", "clsact", "ingress" or a class
identifier. The class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the
qdisc, known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
[QUICKFAIRQUEUEINGCLASS] SECTION OPTIONS¶
The [QuickFairQueueingClass] section manages the traffic control
class of Quick Fair Queueing (qfq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes
one of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to "root".
ClassId=
Configures the unique identifier of the class. It is
specified as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults
to unset.
Weight=
Specifies the weight of the class. Takes an integer in
the range 1...1023. Defaults to unset in which case the kernel default is
used.
Added in version 246.
MaxPacketBytes=
Specifies the maximum packet size in bytes for the class.
When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024. When unset, the
kernel default is used.
Added in version 246.
[BRIDGEVLAN] SECTION OPTIONS¶
The [BridgeVLAN] section manages the VLAN ID configurations of a
bridge master or port, and accepts the following keys. To make the settings
in this section take an effect, VLANFiltering= option has to be
enabled on the bridge master, see the [Bridge] section in
systemd.netdev(5). If at least one valid settings specified in this
section in a .network file for an interface, all assigned VLAN IDs on the
interface that are not configured in the .network file will be removed. If
VLAN IDs on an interface need to be managed by other tools, then the
settings in this section cannot be used in the matching .network file.
VLAN=
The VLAN ID allowed on the port. This can be either a
single ID or a range M-N. Takes an integer in the range 1...4094. This setting
can be specified multiple times. If an empty string is assigned, then the all
previous assignments are cleared.
Added in version 231.
EgressUntagged=
The VLAN ID specified here will be used to untag frames
on egress. Configuring
EgressUntagged= implicates the use of
VLAN= above and will enable the VLAN ID for ingress as well. This can
be either a single ID or a range M-N. This setting can be specified multiple
times. If an empty string is assigned, then the all previous assignments are
cleared.
Added in version 231.
PVID=
The port VLAN ID specified here is assigned to all
untagged frames at ingress. Takes an VLAN ID or negative boolean value (e.g.
"no"). When false, the currently assigned port VLAN ID will be
dropped. Configuring
PVID= implicates the use of
VLAN= setting
in the above and will enable the VLAN ID for ingress as well. Defaults to
unset, and will keep the assigned port VLAN ID if exists.
Added in version 231.
EXAMPLES¶
Example 1. Static network configuration
# /etc/systemd/network/50-static.network
[Match]
Name=enp2s0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
This brings interface "enp2s0" up with a static address.
The specified gateway will be used for a default route.
Example 2. DHCP on ethernet links
# /etc/systemd/network/80-dhcp.network
[Match]
Name=en*
[Network]
DHCP=yes
This will enable DHCPv4 and DHCPv6 on all interfaces with names
starting with "en" (i.e. ethernet interfaces).
Example 3. IPv6 Prefix Delegation (DHCPv6
PD)
# /etc/systemd/network/55-dhcpv6-pd-upstream.network
[Match]
Name=enp1s0
[Network]
DHCP=ipv6
# The lines below are optional, to also assign an address in the delegated prefix
# to the upstream interface. Uncomment the lines below if necessary.
#[Network]
#DHCPPrefixDelegation=yes
#[DHCPPrefixDelegation]
#UplinkInterface=:self
#SubnetId=0
#Announce=no
# If the upstream network does not provides any Router Advertisement (RA) messages,
# then uncomment the lines below to make the DHCPv6 client forcibly started in the
# managed mode.
#[Network]
#IPv6AcceptRA=no
#[DHCPv6]
#WithoutRA=solicit
# If the upstream network provides Router Advertisement (RA) messages with the
# Managed bit unset, then uncomment the lines below to make the DHCPv6 client
# forcibly started in the managed mode when an RA is received.
#[DHCPv6]
#UseAddress=no
#[IPv6AcceptRA]
#DHCPv6Client=always
# /etc/systemd/network/55-dhcpv6-pd-downstream.network
[Match]
Name=enp2s0
[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes
# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no
[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes
This will enable DHCPv6-PD on the interface enp1s0 as an upstream
interface where the DHCPv6 client is running and enp2s0 as a downstream
interface where the prefix is delegated to. The delegated prefixes are
distributed by IPv6 Router Advertisement on the downstream network.
Example 4. IPv6 Prefix Delegation (DHCPv4
6RD)
# /etc/systemd/network/55-dhcpv4-6rd-upstream.network
[Match]
Name=enp1s0
[Network]
DHCP=ipv4
# When DHCPv4-6RD is used, the upstream network does not support IPv6.
# Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
IPv6AcceptRA=no
[DHCPv4]
Use6RD=yes
# /etc/systemd/network/55-dhcpv4-6rd-downstream.network
[Match]
Name=enp2s0
[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes
# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no
[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes
This will enable DHCPv4-6RD on the interface enp1s0 as an upstream
interface where the DHCPv4 client is running and enp2s0 as a downstream
interface where the prefix is delegated to. The delegated prefixes are
distributed by IPv6 Router Advertisement on the downstream network.
Example 5. A bridge with two enslaved
links
# /etc/systemd/network/25-bridge-static.netdev
[NetDev]
Name=bridge0
Kind=bridge
# /etc/systemd/network/25-bridge-static.network
[Match]
Name=bridge0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
# /etc/systemd/network/25-bridge-slave-interface-2.network
[Match]
Name=wlp3s0
[Network]
Bridge=bridge0
This creates a bridge and attaches devices "enp2s0" and
"wlp3s0" to it. The bridge will have the specified static address
and network assigned, and a default route via the specified gateway will be
added. The specified DNS server will be added to the global list of DNS
resolvers.
Example 6. Bridge port with VLAN
forwarding
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
[BridgeVLAN]
VLAN=1-32
PVID=42
EgressUntagged=42
[BridgeVLAN]
VLAN=100-299
[BridgeVLAN]
EgressUntagged=300-400
This overrides the configuration specified in the previous example
for the interface "enp2s0", and enables VLAN on that bridge port.
VLAN IDs 1-32, 42, 100-400 will be allowed. Packets tagged with VLAN IDs 42,
300-400 will be untagged when they leave on this interface. Untagged packets
which arrive on this interface will be assigned VLAN ID 42.
Example 7. Various tunnels
/etc/systemd/network/25-tunnels.network
[Match]
Name=ens1
[Network]
Tunnel=ipip-tun
Tunnel=sit-tun
Tunnel=gre-tun
Tunnel=vti-tun
/etc/systemd/network/25-tunnel-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
/etc/systemd/network/25-tunnel-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
/etc/systemd/network/25-tunnel-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
/etc/systemd/network/25-tunnel-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
This will bring interface "ens1" up and create an IPIP
tunnel, a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
Example 8. A bond device
# /etc/systemd/network/30-bond1.network
[Match]
Name=bond1
[Network]
DHCP=ipv6
# /etc/systemd/network/30-bond1.netdev
[NetDev]
Name=bond1
Kind=bond
# /etc/systemd/network/30-bond1-dev1.network
[Match]
MACAddress=52:54:00:e9:64:41
[Network]
Bond=bond1
# /etc/systemd/network/30-bond1-dev2.network
[Match]
MACAddress=52:54:00:e9:64:42
[Network]
Bond=bond1
This will create a bond device "bond1" and enslave the
two devices with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to
it. IPv6 DHCP will be used to acquire an address.
Example 9. Virtual Routing and Forwarding
(VRF)
Add the "bond1" interface to the VRF master interface
"vrf1". This will redirect routes generated on this interface to
be within the routing table defined during VRF creation. For kernels before
4.8 traffic will not be redirected towards the VRFs routing table unless
specific ip-rules are added.
# /etc/systemd/network/25-vrf.network
[Match]
Name=bond1
[Network]
VRF=vrf1
Example 10. MacVTap
This brings up a network interface "macvtap-test" and
attaches it to "enp0s25".
# /usr/lib/systemd/network/25-macvtap.network
[Match]
Name=enp0s25
[Network]
MACVTAP=macvtap-test
Example 11. A Xfrm interface with physical
underlying device.
# /etc/systemd/network/27-xfrm.netdev
[NetDev]
Name=xfrm0
Kind=xfrm
[Xfrm]
InterfaceId=7
# /etc/systemd/network/27-eth0.network
[Match]
Name=eth0
[Network]
Xfrm=xfrm0
This creates a "xfrm0" interface and binds it to the
"eth0" device. This allows hardware based ipsec offloading to the
"eth0" nic. If offloading is not needed, xfrm interfaces can be
assigned to the "lo" device.
NOTES¶
- 1.
- 💣💥🧨💥💥💣 Please note that
those configuration files must be available at all times. If /usr/local/
is a separate partition, it may not be available during early boot, and
must not be used for configuration.
- 2.
- System and Service Credentials
- 3.
- Link-Local Multicast Name Resolution
- 4.
- Multicast DNS
- 5.
- DNS-over-TLS
- 6.
- DNSSEC
- 7.
- IEEE 802.1AB-2016
- 8.
- RFC 5227
- 9.
- IP Sysctl
- 10.
- RFC 4941
- 11.
- RFC 3704
- 12.
- RFC 3069
- 13.
- RFC 6275
- 14.
- RFC 4862
- 15.
- RFC 3041
- 16.
- NetLabel
- 17.
- Linux Security Modules (LSMs)
- 18.
- NetLabel Fallback Peer Labeling
- 19.
- NFT
- 20.
- RFC 3484
- 21.
- Type of Service
- 22.
- Differentiated services
- 23.
- Virtual Routing and Forwarding (VRF)
- 24.
- RFC 4191
- 25.
- RFC 8520
- 26.
- RFC 4039
- 27.
- RFC 7844
- 28.
- C-style escapes
- 29.
- RFC 9463
- 30.
- RFC 3442
- 31.
- RFC 5969
- 32.
- RFC 7084
- 33.
- RFC 8925
- 34.
- RFC 3315
- 35.
- RFC 8415
- 36.
- RFC 4291
- 37.
- RFC 7217
- 38.
- RFC 8781
- 39.
- RFC 2131
- 40.
- RFC 2132
- 41.
- RFC 1542
- 42.
- RFC 4039
- 43.
- RFC 4861
