NAME¶
bwctld -
Band
width
Con
tro
l server.
SYNOPSIS¶
bwctld [
-a auth_mode ] [
-c conf_dir ] [
-e facility ] [
-f ] [
-G group ] [
-h ] [
-R var_dir ] [
-S nodename:port ] [
-U user ] [
-Z ]
DESCRIPTION¶
bwctld is a server program designed to schedule and run
Iperf,
Thrulay or
Nuttcp throughput tests. These tests can measure
maximum TCP bandwidth, with various tunable options available, or, by doing a
UDP test, he delay, jitter and datagram loss of a network.
Aside from actually running throughput tests, the main function of
bwctld
is to determine which tests are allowable based upon the policy restrictions
configured by the system administrator.
bwctld was designed to be run as a stand-alone daemon process. It uses
the classic accept/fork model of handling new requests.
Most of the command line options for
bwctld have analogous options in the
bwctld.conf file. The command line takes precedence.
OPTIONS¶
- -a auth_mode
- Specify the authentication modes the server is willing to use for
communication. auth_mode should be set as a character string with
any or all of the characters "AEO". The modes are:
- A
- [A]uthenticated. This mode encrypts the control connection.
- E
- [E]ncrypted. This mode encrypts the control connection. If the test
supports encryption, this mode will additionally encrypt the test stream.
(Encryption of the test stream is not currently supported, so this mode is
currently identical to authenticated.)
- O
- [O]pen. No encryption of any kind is done.
The server can specify all the modes with which it is willing to communicate.
The most strict mode that both the server and the client are willing to use
will be selected.
- Default:
- "AEO".
- -c conf_dir
- Specify the directory that holds the bwctld configuration
files.
- Default:
- Current working directory.
- -e facility
- Syslog facility to which messages are logged.
- -f
- Enables the bwctld daemon to run with root permissions.
There are legitimate reasons to run bwctld as root, but it is
risky. Forcing this additional option will make it less likely root
permissions are accidently used.
- -G group
- Specify the gid for the bwctld process. group can be
specified using a valid group name or by using -gid. This option is only
used if bwctld is started as root.
- -h
- Print a help message.
- -R var_dir
- Specify the directory to hold the bwctld.pid file.
- Default:
- Current directory
- -S nodename:port
- Specify the address and port on which bwctld will listen for
requests. nodename can be specified using a DNS name or using the
textual representation of the address. It is possible to set the source
address without setting the port simply by leaving off the ':' and
port specification. If an IPv6 address is specified, note that the
accepted format contains nodename in square brackets, such as:
[fe80::fe9f:62d8]. This ensures the port number is distinct from the
address specification.
- Default:
- nodename is wildcarded as any currently available address.
port is 4823.
- -U user
- Specify the uid for the bwctld process. user can be
specified using a valid user name or by using -uid. This option is only
used if bwctld is started as root.
- -Z
- Run the master bwctld process in the foreground. In this mode,
error messages are printed to stderr as well as being sent to syslog.
Also, normal terminal controls are available. (i.e., <Cntr-C> will
cause the daemon to kill it's child processes and exit.) This is useful
for debugging.
REQUIREMENTS¶
The
bwctld daemon prefers a reasonably synchronized clock. It is
scheduling tests and needs to be sure it has the same idea of when a test
should take place as does the peer test system. Therefore,
bwctld
attempts to use NTP specific system calls to determine the accuracy of the
local clock. If those system calls are unavailable, or the administrator has
set the
allow_unsync option in the
bwctld.conf file, then
bwctld will blindly accept tests assuming the clock is synchronized to
within the
sync_fuzz value that is also defined in the
bwctld.conf file. If this assumption does not hold true, then the test
will eventually fail. Unfortunately, because the time offset is not detected
early, this test will have taken up a schedule slot.
FILES¶
bwctld.pid
bwctld.conf
bwctld.limits
bwctld.keys
SEE ALSO¶
There are more details on configuring the
bwctld daemon in the
bwctld.conf(5) manual page. Details on configuring the policy is in the
bwctld.limits(5) and
bwctld.keys(5) manual pages. Information on the client is
in the
bwctl(1) manual page. For more of an overview of the full functionality
and architecture see the
http://e2epi.internet2.edu/bwctl/ web site.
For details on
Iperf, see the
http://sourceforge.net/projects/iperf web
site.
For details on
Nuttcp, see the
http://www.wcisd.hpc.mil/nuttcp/Nuttcp-HOWTO.html web site.
For details on
Thrulay, see the
http://e2epi.internet2.edu/thrulay/ web
site.
ACKNOWLEDGMENTS¶
This material is based in part on work supported by the National Science
Foundation (NSF) under Grant No. ANI-0314723. Any opinions, findings and
conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the NSF.
