NAME¶
scamper —
parallel Internet measurement utility
SYNOPSIS¶
scamper |
[ -?Dv
]
[-c command
]
[-p pps
]
[-w window
]
[-M monitorname
]
[-l listname
]
[-L listid
]
[-C cycleid
]
[-o outfile
]
[-F firewall
]
[-d debugfile
]
[-e pidfile
]
[-O options
]
[-i IPs | -I cmds | -f file | -P port | -U unix-dom
] |
DESCRIPTION¶
The
scamper utility provides the ability to
execute Internet measurement techniques to IPv4 and IPv6 addresses, in
parallel, to fill a specified packets-per-second rate. Currently,
scamper supports the well-known traceroute
and ping techniques, as well as MDA traceroute, alias resolution, some parts
of tbit, sting, and neighbour discovery.
scamper has four modes of operation. First,
scamper can be supplied a list of addresses
on the command line with the
-i option.
scamper will then execute a command with
each of the supplied addresses, in parallel, and output the results as each
task completes. Second,
scamper can be
supplied a list of addresses in a listfile, one address per line, using the
-f option. Third,
scamper can be supplied a list of complete
commands on the command line with the
-I
option. Finally,
scamper can be instructed
to listen on a port specified with the
-P
option only accessible on the local host, or on a unix domain socket specified
with the
-U option, where it can take
commands dynamically.
The options are as follows:
-?- prints a list of command line options and a synopsis of each.
-v- causes
scamper to output version
information and exit.
-D- With this option set,
scamper will
detach and become a daemon. Use with the
-P or
-U options.
-c
command- specifies the command for
scamper to
use by default. The current choices for this option are:
- dealias
- neighbourdisc
- ping
- trace
- tracelb
- sniff
- sting
- tbit
scamper uses trace by default. The
available commands and their options are documented below.
-p
pps- specifies the target packets-per-second rate for
scamper to reach. By default, this
value is 20.
-w
window- specifies the maximum number of tasks that may be probed in parallel. A
value of zero places no upper limit. By default, zero is used.
-M
monitorname- specifies the canonical name of machine where
scamper is run. This value is used when
recording the output in a warts output file.
-l
listname- specifies the name of the list when run from the command line. This value
is used when recording the output in a warts output file.
-L
listid- specifies the numerical id of the list when run from the command line.
This value is used when recording the output in a warts output file.
-C
cycleid- specifies the numerical cycle id to begin with when run from the command
line. This value is used when recording the output in a warts output
file.
-o
outfile- specifies the default output file to write measurement results to. By
default, stdout is used.
-F
firewall- specifies that scamper may use the firewall in measurements that require
it. To use the firewall on FreeBSD and MacOS X systems, pass ipfw
here.
-d
debugfile- specifies a filename to write debugging messages to. By default, no
debugfile is used, though debugging output is sent to stderr if scamper is
built for debugging.
-e
pidfile- specifies a file to write scamper's process ID to. If scamper is built
with privilege separation, the ID of the unprivileged process is
written.
-O
options- allows scamper's behaviour to be further tailored. The current choices for
this option are:
- text output results using plain text.
Suitable for interactive use.
- warts output results to a warts binary
file. Suitable for archiving measurement results and for use by
researchers as it records details that cannot be easily represented
with the text option.
- planetlab tell scamper it is running on a
planetlab system. Necessary to use planetlab's safe raw sockets.
- rawtcp tell scamper to use IPPROTO_RAW
socket to send IPv4 TCP probes, rather than a datalink socket.
- select tell scamper to use
select(2) rather than
poll(2)
- kqueue tell scamper to use
kqueue(2) rather than
poll(2) on systems where
kqueue(2) is available.
- epoll tell scamper to use
epoll(7) rather than
poll(2) on systems where
epoll(7) is available.
- tsps the input file consists of a
sequence of IP addresses for pre-specified IP timestamps.
- cmdfile the input file consists of
complete commands.
- dlts use timestamps from the datalink
layer, if possible.
- outcopy write a copy of all data written
by scamper with the default output method.
- debugfileappend append to the debugfile
specified with the
-d option. The
default is to truncate the debugfile.
-i
IP 1..N- specifies the addresses to probe, on the command line, using the command
specified with the
-c option.
-f
listfile- specifies the input file to read for target addresses, one per line, and
uses the command specified with the
-c
option on each.
-I
cmds.- specifies complete commands, including target addresses, for scamper to
execute.
-P
port- specifies that
scamper provide a
control socket listening on the specified port on the local host.
-U
unix domain socket- specifies that
scamper provide a
control socket listening on the specified socket in the unix domain.
TRACE OPTIONS¶
The trace command is used for conducting traceroute. The following variations of
the
traceroute(8) options are available:
trace [
-MQT
]
[
-c confidence
]
[
-d dport
]
[
-f firsthop
]
[
-g gaplimit
]
[
-G gapaction
]
[
-l loops
]
[
-L loopaction
]
[
-m maxttl
]
[
-p payload
]
[
-P method
]
[
-q attempts
]
[
-s sport
]
[
-S srcaddr
]
[
-t tos
]
[
-U userid
]
[
-w wait
]
[
-W wait-probe
]
[
-z gss-entry
]
[
-Z lss-name
]
-c
confidence- specifies that a hop should be probed to a specified confidence level (95%
or 99%) to be sure the trace has seen all interfaces that will reply for
that hop.
-d
dport- specifies the base destination port value to use for UDP-based and
TCP-based traceroute methods. For ICMP-paris, this option sets the ICMP
checksum value.
-f
firsthop- specifies the TTL or HLIM value to begin probing with. By default, a first
hop of one is used.
-g
gaplimit- specifies the number of unresponsive hops permitted until a check is made
to see if the destination will respond. By default, a gap limit of 5 hops
is used. Setting the gap limit to 0 disables the gap limit, but doing this
is not recommended.
-G
gapaction- specifies what should happen if the gaplimit condition is met. A value of
1 (default) means halt probing, while a value of 2 means send last-ditch
probes.
-m
maxttl- specifies the maximum TTL or HLIM value that will be probed. By default,
there is no restriction, apart from the 255 hops that the Internet
protocols allow.
-M- specifies that path MTU discovery (PMTUD) should be attempted for the path
when the initial traceroute completes.
scamper will not conduct PMTUD unless
it is probing a responsive destination, as otherwise there is no way to
distinguish all packets being lost from just big packets (larger than MTU)
being lost.
-l
loops- specifies the maximum number of loops permitted until probing stops. By
default, a value of one is used. A value of zero disables loop
checking.
-L
loopaction- specifies the action to take when a loop is encountered. A value of 1
tells scamper to probe beyond the first loop in the trace.
-p
payload- specifies the payload of the probe to use as a base. The payload is
specified in hexadecimal. Note that the payload supplied is merely a base;
the first 2 bytes may be modified to accomplish ICMP-Paris and UDP-Paris
traceroute.
-P
method- specifies the traceroute method to use.
scamper currently supports five
different probe methods: UDP, ICMP, UDP-paris, ICMP-paris, TCP, and
TCP-ACK. By default, UDP-paris is used.
-q
attempts- specifies the maximum number of attempts to obtain a response per hop. By
default, a value of two is used.
-Q- specifies that all allocated probes are sent, regardless of how many
responses have been received.
-s
sport- specifies the source port value to use. For ICMP-based methods, this
option specifies the ICMP identifier to use.
-S
srcaddr- specifies the source address to use in probes. The address cannot be
spoofed.
-t
tos- specifies the value to set in the IP ToS/DSCP + ECN byte. By default, this
byte is set to zero.
-T- specifies that time exceeded messages from the destination do not cause
the trace to be defined as reaching the destination.
-U
userid- specifies an unsigned integer to include with the data collected; the
meaning of the user-id is entirely up to the user and has no effect on the
behaviour of traceroute.
-w
wait- specifies how long to wait, in seconds, for a reply. By default, a value
of 5 is used.
-W
wait-probe- specifies the minimum time to wait, in 10s of milliseconds, between
sending consecutive probes. By default the next probe is sent as soon as
possible.
-z
gss-entry- specifies an IP address to halt probing when encountered; used with the
double-tree algorithm.
-Z
lss-name- specifies the name of the local stop set to use when determining when to
halt probing backwards; used with the double-tree algorithm.
PING OPTIONS¶
The ping command is used for conducting ping. The following variations of the
ping(8) options are available:
ping [
-R
]
[
-B payload
]
[
-c probecount
]
[
-C icmp-sum
]
[
-d dport
]
[
-F sport
]
[
-i wait
]
[
-m ttl
]
[
-M MTU
]
[
-o replycount
]
[
-O options
]
[
-p pattern
]
[
-P method
]
[
-U userid
]
[
-s size
]
[
-S srcaddr
]
[
-T timestamp
]
[
-z tos
]
-B
payload- specifies, in a hexadecimal string, the payload to include in each
probe.
-c
probecount- specifies the number of probes to send before exiting. By default, a value
of 4 is used.
-C
icmp-sum- specifies the ICMP checksum to use when sending a probe. The payload of
each probe will be manipulated so that the checksum is valid.
-d
dport- specifies the destination port to use in each TCP/UDP probe.
-F
sport- specifies the source port to use in each TCP/UDP probe, and the ICMP ID to
use in ICMP probes.
-i
wait- specifies the length of time to wait, in seconds, between probes. By
default, a value of 1 is used.
-m
ttl- specifies the TTL value to use for outgoing packets. By default, a value
of 64 is used.
-M
MTU- specifies a pseudo MTU value. If the response packet is larger than the
pseudo MTU, an ICMP packet too big (PTB) message is sent.
-o
replycount- specifies the number of replies required at which time probing may cease.
By default, all probes are sent.
-O
options- The current choices for this option are:
- spoof specifies that the source address
is to be spoofed according to the address specified with the
-S option. The address scamper
would otherwise use as the source address is embedded in the payload
of the probe.
-p
pattern- specifies the pattern, in hex, to use in probes. Up to 16 bytes may be
specified. By default, each probe's bytes are zeroed.
-P
method- specifies the type of ping packets to send. By default, ICMP echo requests
are sent. Choices are: icmp-echo, icmp-time, tcp-ack, tcp-ack-sport, udp,
and udp-dport.
-U
userid- specifies an unsigned integer to include with the data collected; the
meaning of the user-id is entirely up to the user and has no effect on the
behaviour of ping.
-R- specifies that the record route IP option should be used.
-s
size- specifies the size of the probes to send. The probe size includes the
length of the IP and ICMP headers. By default, a probe size of 84 bytes is
used for IPv4 pings, and 56 bytes for IPv6 pings.
-S
srcaddr- specifies the source address to use in probes. The address can be spoofed
if -O spoof is included.
-T
timestamp- specifies that an IP timestamp option be included. The timestamp option
can either be: tsprespec where IP addresses of devices of interest can be
specified; tsonly, where timestamps are embedded by devices but no IP
addresses are included; and tsandaddr, where timestamps and IP addresses
are included by devices in the path. See the examples section for more
information.
-z
tos- specifies the value to use in the IPv4 ToS/DSCP + ECN byte. By default,
this byte is set to zero.
DEALIAS OPTIONS¶
The dealias command is used to send probes for the purpose of alias resolution.
It supports the mercator technique, where aliases are inferred if a router
uses a different address when sending an ICMP response; the ally technique,
where aliases are inferred if a sequence of probes sent to alternating IP
addresses yields responses with incrementing, interleaved IP-ID values;
radargun, where probes are sent to a set of IP addresses in multiple rounds
and aliases are inferred by post-processing the results; prefixscan, where an
alias is searched in a prefix for a specified IP address; and bump, where two
addresses believed to be aliases are probed in an effort to force their IP-ID
values out of sequence. The following options are available for the
scamper dealias command:
dealias
[
-d dport
]
[
-f fudge
]
[
-m method
]
[
-o replyc
]
[
-O option
]
[
-p probe-options
]
[
-q attempts
]
[
-r wait-round
]
[
-s sport
]
[
-t ttl
]
[
-U userid
]
[
-w wait-timeout
]
[
-W wait-probe
]
[
-x exclude
]
-d
dport- specifies the destination port to use when sending probes. Only valid for
the mercator technique; destination ports can be specified in probedefs
defined with
-p for other alias
resolution methods.
-f
fudge- specifies a fudge factor for alias matching. Defaults to 200. Only valid
for ally and bump.
-m
method- specifies which method to use for alias resolution. Valid options are:
ally, bump, mercator, prefixscan, and radargun.
-o
replyc- specifies how many replies to wait for. Only valid for prefixscan.
-O
option- allows alias resolution behaviour to be further tailored. The current
choices for this option are:
- inseq where IP-ID values are required to
be strictly in sequence (with no tolerance for packet reordering)
- shuffle randomise the order of probes
sent each round; only valid for radargun probing.
- nobs do not allow for byte swapped IP-ID
values in responses. Valid for ally and prefixscan.
-p
probedef- specifies a definition for a probe. Possible options are:
-c
sum- specifies what ICMP checksum to use for ICMP probes. The payload of
the probe will be altered appropriately.
-d
dst-port- specifies the destination port of the probe. Defaults to 33435.
-F
src-port- specifies the source port of the probe. Defaults to (pid & 0x7fff)
+ 0x8000.
-i
IP- specifies the destination IP address of the probe.
-P
method- specifies which method to use for the probe. Valid options are: udp,
udp-dport, tcp-ack, tcp-ack-sport, tcp-syn-sport, and icmp-echo.
-s
size- specifies the size of the probes to send.
-t
ttl- specifies the IP time to live of the probe.
The ally method accepts up to two probe definitions; the prefixscan method
expects one probe definition; radargun expects at least one probe
definition; bump expects two probe definitions.
-q
attempts- specifies how many times a probe should be retried if it does not obtain a
useful response.
-r
wait-round- specifies how many milliseconds to wait between probing rounds with
radargun.
-s
sport- specifies the source port to use when sending probes. Only valid for
mercator.
-t
ttl- specifies the time-to-live of probes sent. Only valid for mercator.
-U
userid- specifies an unsigned integer to include with the data collected; the
meaning of the user-id is entirely up to the user and has no effect on the
behaviour of dealias.
-w
wait-timeout- specifies how long to wait in milliseconds for a reply from the remote
host.
-W
wait-probe- specifies how long to wait in milliseconds between probes.
-x
exclude- specifies an IP address to exclude when using the prefixscan method. May
be specified multiple times to exclude multiple addresses.
NEIGHBOUR DISCOVERY OPTIONS¶
The neighbourdisc command attempts to find the layer-2 address of a given IP
address using IPv4 ARP or IPv6 Neighbour Discovery. The following options are
availible for the
scamper neighbourdisc
command:
neighbourdisc [
-FQ
]
[
-i interface
]
[
-o reply-count
]
[
-q attempts
]
[
-w wait
]
-F- specifies that we only want the first response.
-Q- specifies that we want to send all attempts.
-i
interface- specifies the name of the interface to use for neighbour discovery.
-o
reply-count- specifies how many replies we wait for.
-q
attempts- specifies how many probes we send out.
-w
wait- specifies how long to wait between probes in milliseconds. Defaults to
1000.
TBIT OPTIONS¶
The tbit command can be used to infer TCP behaviour of a specified host. At
present, it implements tests to check the ability of the host to respond to
ICMP Packet Too Big messages, and respond to Explicit Congestion Notification.
The following options are available for the
scamper tbit command:
tbit
[
-t type
]
[
-p app
]
[
-d dport
]
[
-s sport
]
[
-m mss
]
[
-M mtu
]
[
-O option
]
[
-P ptbsrc
]
[
-S srcaddr
]
[
-u url
]
-t
type- specifies which type of testing to use. Valid options are: pmtud, ecn,
null, sack-rcvr.
-p
app- specifies what kind of traffic to generate for testing. Destination port
defaults the application standard port. Valid applications are: smtp,
http, dns, ftp.
-d
dport- specifies the destination port for the packets being sent. Defaults are
application-specific.
-s
sport- specifies the source port for the packets being sent. Default is based of
the
scamper process id.
-m
mss- specifies the maximum segment size to advertise to the remote host.
-M
mtu- specifies the MTU to use in a Packet Too Big message.
-O
option- allows tbit behaviour to be further tailored. The current choice for this
option is:
- blackhole for PMTUD testing, do not send
Packet Too Big messages; this tests to ability of a host to infer a
PMTUD blackhole and work around it.
-P
ptbsrc- specifies the source address that should be used to send Packet Too Big
messages in the pmtud test.
-S
srcaddr- specifies the source address that should be used in TCP packets sent by
the tbit test.
-u
url- specifies a url for the http application.
TRACELB OPTIONS¶
The tracelb command is used to infer all per-flow load-balanced paths between a
source and destination. The following options are available for the
scamper tracelb command:
tracelb
[
-c confidence
]
[
-d dport
]
[
-f firsthop
]
[
-g gaplimit
]
[
-P method
]
[
-q attempts
]
[
-Q maxprobec
]
[
-s sport
]
[
-t tos
]
[
-U userid
]
[
-w wait-timeout
]
[
-W wait-probe
]
-c
confidence- specifies the level of confidence we want to attain that there are no more
parallel load balanced paths at a given hop. Valid values are 95 (default)
and 99, for 95% confidence and 99% confidence respectively.
-d
dport- specifies the base destination port to use. Defaults to 33435, the default
used by traceroute(8).
-f
firsthop- specifies how many hops away we should start probing.
-g
gaplimit- specifies how many consecutive unresponsive hops are permitted before
probing down a branch halts. Defaults to three.
-P
method- specifies which method we should use to do the probing. Valid options are:
"udp-dport", "icmp-echo", "udp-sport",
"tcp-sport", and "tcp-ack-sport". Defaults to
"udp-dport".
-q
attempts- specifies how many probes we should send in an attempt to receive a reply.
Defaults to 2.
-Q
maxprobec- specifies the maximum number of probes we ever want to send. Defaults to
3000.
-s
sport- specfies to the source port to use when sending probes. Default based on
process ID.
-t
tos- specifies the value for the IP Type-of-service field for outgoing probes.
Defaults to 0.
-U
userid- specifies an unsigned integer to include with the data collected; the
meaning of the user-id is entirely up to the user and has no effect on the
behaviour of tracelb.
-w
wait-timeout- specifies in seconds how long to wait for a reply to a probe. Defaults to
5.
-W
wait-probe- specifies in 1/100ths of seconds how long to wait between probes. Defaults
to 25 (i.e. 250ms).
STING OPTIONS¶
The sting command is used to infer one-way loss using an algorithm with TCP
probes. It requires the firewall be enabled in scamper using the
-F option. The following options are
available for the
scamper sting command:
sting
[
-c count
]
[
-d dport
]
[
-f distribution
]
[
-h request
]
[
-H hole
]
[
-i inter
]
[
-m mean
]
[
-s sport
]
-c
count- specifies the number of samples to make. By default 48 samples are sent,
as this value is the current default of the FreeBSD TCP reassembly queue
length. Sting 0.7 uses 100 samples.
-d
dport- specifies the base destination port to use. Defaults to 80, the default
port used by the HTTP protocol.
-f
distribution- specifies the delay distribution of samples. By default a uniform
distribution is constructed. Other distributions are currently not
implemented in scamper's implementation of sting.
-h
request- specifies the default request to make. Currently not implemented.
-H
hole- specifies the size of the initial hole left in the request. The default is
3 bytes, the same as sting-0.7.
-i
inter- specifies the inter-phase delay between data seeding and hole filling, in
milliseconds. By default, sting waits 2000ms between phases.
-m
mean- specifies the mean rate to send packets in the data phase, in
milliseconds. By default, sting waits 100ms between probes.
-s
sport- specfies to the source port to use when sending probes. Default is based
on the process ID.
SNIFF OPTIONS¶
The sniff command is used to capture packets matching a specific signature. At
present, the only supported signature is ICMP echo packets with a specific ID
value, or packets containing such a quote. The following options are available
for the
scamper sniff command:
sting
[
-c limit-pktc
]
[
-G limit-time
]
[
-S ipaddr
]
[
-U userid
]
<expression>
-c
limit-pktc- specifies the maximum number of packets to capture.
-G
limit-time- specifies the maximum time, in seconds, to capture packets.
-S
ipaddr- specifies the IP address that packets must arrive using. scamper uses the
IP address to identify the appropriate interface to listen for
packets.
-U
userid- specifies an unsigned integer to include with the data collected; the
meaning of the user-id is entirely up to the user and has no effect on the
behaviour of sniff.
The sole supported expression is icmp[icmpid] == X, where X is the ICMP-ID to
select.
DATA COLLECTION FEATURES¶
scamper has two data output formats. The
first is a human-readable format suitable for one-off data collection and
measurement. The second, known as
warts, is
a binary format that records much more meta-data and is more precise than the
human-readable format.
scamper is designed for Internet-scale
measurement, where large lists of targets are supplied for probing.
scamper has the ability to probe multiple
lists simultaneously, with each having a mix rate that specifies the priority
of the list.
scamper can also make multiple
cycles over a list of addresses.
When writing output to a
warts file,
scamper records details of the list and
cycle that each measurement task belongs to.
CONTROL SOCKET¶
When started with the
-P option,
scamper allows inter-process communication
via a TCP socket bound to the supplied port on the local host. This socket is
useful for controlling the operation of a long-lived
scamper process. A client may interact with
scamper by using
telnet(1) to open a connection
to the supplied port.
The following control socket commands are available.
exit- The exit command closes the current control socket connection.
attach- The attach command changes how
scamper
accepts and replies to commands, returning results straight over the
control socket. See ATTACH section below for
details on which commands are accepted.
get
argument- The get command returns the current setting for the supplied argument.
Valid argument values are: holdtime, monitorname, pid, pps, sport,
version.
set
argument ...- The set command sets the current setting for the supplied argument. Valid
argument values are: holdtime, monitorname, pps.
source
argument ...-
add
arguments- The
source add command allows a new
input source to be added. It accepts the following arguments:
name
string- The name of the source. This parameter is mandatory.
descr
string- An optional string describing the source.
command
string- The command to execute for each address supplied. If not supplied,
the default command is used.
list_id
uint32_t- An optional numeric list identifier, assigned by a human. If not
supplied, a value of zero is used.
cycle_id
uint32_t- An optional numeric initial cycle identifier to use, assigned by a
human. If not supplied, a value of one is used.
priority
uint32_t- An optional numeric value that specifies the mix rate of
measurements from the source compared to other sources. If not
supplied, a mix rate of one is used. A value of zero causes the
source to be created, but not actively used.
outfile
string- The name of the output file to write results to, previously
defined with
outfile open. If
not supplied, the default output file is used.
file
string- The name of the input file to read target addresses from. This
parameter is mandatory if the source is a managed source.
cycles
integer- The number of cycles to make over the target address file. If
zero,
scamper will loop
indefinitely over the file. This parameter is ignored unless a
managed source is defined.
autoreload
[on |
off
]- This parameter specifies if the target address file should be
re-read whenever a cycle is completed, or if the same set of
target addresses as the previous cycle should be used. If not
specified, the file is not automatically reloaded at cycle
time.
update
name arguments- The
source update command allows
some properties of an existing source to be modified. The source to
update is specified with the name
parameter. Valid parameters are: autoreload, cycles, and
priority.
list
...- The
source list command provides a
listing of all currently defined sources. The optional third
name parameter restricts the listing
to the source specified.
cycle
name- The
source cycle command manually
inserts a cycle marker in an adhoc source.
delete
name- The
source delete command deletes
the named source, if possible.
outfile
argument ...- The outfile commands provide the ability to manage output files. It
accepts the following arguments:
open
...- The
outfile open command allows a
new output file to be defined. It accepts the following parameters:
name
alias- The alias of the output file. This parameter is mandatory.
file
string- The filename of the output file. This parameter is mandatory.
mode
[truncate |
append
]- How the file will be opened. If the append mode is used, any
existing file with the specified name will be appended to. If the
truncate mode is used, any existing file will be truncated when it
is opened.
close
alias- The
outfile close command allows an
existing output file to be closed. The mandatory
alias parameter specifies which
output file to close. An output file that is currently referenced is
not able to be closed. To close a file that is currently referenced, a
new outfile must be opened, and then the
outfile swap command be used.
swap
alias1 alias2- The
outfile swap command swaps the
file associated with each output file.
list- The
outfile list command outputs a
list of the existing outfiles.
observe
sources- This command allows for monitoring of source events. When executed, the
control socket will then supply event notices whenever a source is added,
updated, deleted, finished, or cycled. Each event is prefixed with a count
of the number of seconds elapsed since the Unix epoch. The following
examples illustrate the event monitoring capabilities:
EVENT 1169065640 source add name
'foo' list_id 5 priority 1
EVENT 1169065641 source update
'foo' priority 15
EVENT 1169065642 source cycle
'bar' id 2
EVENT 1169065650 source finish
'bar'
EVENT 1169065661 source delete
'foo'
shutdown
argument- The shutdown argument allows the
scamper process to be exited cleanly.
The following arguments are supported
done- The
shutdown done command requests
that scamper shuts down when the
current tasks, as well as all remaining cycles, have completed.
flush- The
shutdown flush command requests
that scamper flushes all remaining
tasks queued with each list, finishes all current tasks, and then
shuts down.
now- The
shutdown now command causes
scamper to shutdown immediately.
Unfinished tasks are purged.
cancel- The
shutdown cancel command cancels
any pending shutdown.
ATTACH MODE¶
In attach mode, none of the usual interactive mode commands are usable. Instead,
commands may be entered directly and results will be sent back directly over
the control socket. Commands are specified just as they would be with the -I
flag for a command-line invocation of
scamper. Replies are split into lines by
single \n characters and have one of the following formats:
ERR
...- A line staring with the 3 characters "ERR" indicate an error has
occured. The rest of the line will contain an error message.
OK
id-num- A line with the 2 characters "OK" indicates that scamper has
accepted the command.
scamper versions
after 20110623 return an id number associated with the command, which
allow the task to be halted by subsequently issuing a "halt"
instruction.
MORE- A line with just the 4 characters "MORE" indicates that scamper
has the capacity to accept more probing commands to run in parallel.
DATA
length- A line starting with the 4 characters "DATA" follow by a space
then a base-10 number indicates the start of result.
length specifies the number of characters
of the data, including newlines. The data is in binary warts format and
uuencoded before transmission.
To exit attached mode the client must send a single line containing
"done". To halt a command that has not yet completed, issue a
"halt" instruction with the id number returned when the command was
accepted as the sole parameter.
EXAMPLES¶
To use the default traceroute command to trace the path to 192.0.2.1:
scamper -i 192.0.2.1
To infer Path MTU changes in the network and associate them with a traceroute
path:
scamper -I "trace -P udp-paris -M 192.0.2.1"
To use paris traceroute with ICMP probes, using 3 probes per hop, sending all
probes, writing to a specified warts file:
scamper -O warts -o file.warts -I "trace -P icmp-paris -q 3 -Q
192.0.2.1"
To ping a series of addresses defined in
filename, probing each address 10 times:
scamper -c "ping -c 10"
filename
Care must be taken with shell quoting when using commands with multiple levels
of quoting, such as when giving a probe description with a dealias command.
The following sends UDP probes to alternating IP addresses, one second apart,
and requires the IP-ID values returned to be strictly in sequence.
scamper -O warts -o ally.warts -I "dealias -O inseq -W 1000 -m ally -p '-P
udp -i 192.0.2.1' -p '-P udp -i 192.0.2.4'"
Alternatively, the following accomplishes the same, but without specifying the
UDP probe method twice.
scamper -O warts -o ally.warts -I "dealias -O inseq -W 1000 -m ally -p '-P
udp' 192.0.2.1 192.0.2.4"
The following command scans 198.51.100.0/28 for a matching alias to 192.0.2.4,
but skips 198.51.100.3.
scamper -O warts -o prefixscan.warts -I "dealias -O inseq -W 1000 -m
prefixscan -p '-P udp' -x 198.51.100.3 192.0.2.4 198.51.100.0/28"
The following uses UDP probes to enumerate all per-flow load-balanced paths
towards 192.0.2.6 to 99% confidence; it varies the source port with each
probe.
scamper -I "tracelb -P udp-sport -c 99 192.0.2.6"
SEE ALSO¶
ping(8),
traceroute(8),
libscamperfile(3),
sc_ally(1),
sc_analysis_dump(1),
sc_attach(1),
sc_tracediff(1),
sc_wartscat(1),
sc_wartsdump(1),
sc_warts2json(1),
sc_warts2pcap(1),
sc_warts2text(1),
S. Savage,
Sting: a TCP-based Network Measurement Tool,
1999 USENIX Symposium on Internet Technologies and
Systems.
R. Govindan and
H. Tangmunarunkit, Heuristics for
Internet Map Discovery, Proc. IEEE INFOCOM
2000.
N. Spring,
R. Mahajan, and D.
Wetherall, Measuring ISP topologies with
Rocketfuel, Proc. ACM SIGCOMM 2002.
A. Medina,
M. Allman, and S. Floyd,
Measuring the evolution of transport protocols in the
Internet, Proc. ACM/SIGCOMM Internet Measurement
Conference 2004.
M. Luckie,
K. Cho, and B. Owens,
Inferring and Debugging Path MTU Discovery Failures,
Proc. ACM/SIGCOMM Internet Measurement Conference
2005.
B. Donnet,
P. Raoult, T. Friedman, and
M. Crovella, Efficient algorithms
for large-scale topology discovery, Proc. ACM
SIGMETRICS 2005.
B. Augustin,
X. Cuvellier, B. Orgogozo,
F. Viger, T. Friedman,
M. Latapy, C. Magnien, and
R. Teixeira, Avoiding traceroute
anomalies with Paris traceroute, Proc. ACM/SIGCOMM
Internet Measurement Conference 2006.
B. Augustin,
T. Friedman, and R.
Teixeira, Measuring Load-balanced Paths in the
Internet, Proc. ACM/SIGCOMM Internet Measurement
Conference 2007.
A. Bender,
R. Sherwood, and N. Spring,
Fixing Ally's growing pains with velocity modeling,
Proc. ACM/SIGCOMM Internet Measurement Conference
2008.
M. Luckie,
Scamper: a Scalable and Extensible Packet Prober for Active
Measurement of the Internet, Proc. ACM/SIGCOMM
Internet Measurement Conference 2010.
AUTHORS¶
scamper is written by Matthew Luckie
<mjl@luckie.org.nz>. Alistair King contributed an initial implementation
of Doubletree; Ben Stasiewicz contributed an initial implementation of TBIT's
PMTUD test; Stephen Eichler contributed an initial implementation of TBIT's
ECN test; Boris Pfahringer adapted
scamper
to use GNU autotools, modularised the tests, and updated this man page. Brian
Hammond of Internap Network Services Corporation provided an initial
implementation of scamper's json output format.
ACKNOWLEDGEMENTS¶
scamper development was initially funded by
the WIDE project in association with CAIDA. Boris' work was funded by the
University of Waikato's Centre for Open Source Innovation.
