Ubuntu Manpage: distccd - distributed C/C++ compiler server

NAME

       distccd - distributed C/C++ compiler server

SYNOPSIS

       distccd --daemon [OPTIONS]

DESCRIPTION

distccd is the server for the distcc(1) distributed compiler. It accepts and runs
compilation jobs for network clients.

distcc can run over either TCP or a connection command such as ssh(1). TCP connections
are fast but relatively insecure. SSH connections are secure but slower.

For SSH connections, distccd must be installed on the volunteer but should not run as a
daemon -- it will be started over SSH as needed. SSH connections have several advantages:
neither the client nor server listens on any new ports; compilations run with the
privileges of the user that requested them; unauthorized users cannot access the server;
and source and output is protected in transit.

For TCP connections, distccd can run either from an inetd-style program, or as a
standalone server. Standalone mode is recommended because it is slightly more efficient
and allows distccd to regulate the number of incoming jobs. The --listen and --allow
options can be used for simple IP-based access control.

distcc may be started either by root or any other user. If run by root, it gives away
privileges and changes to the user specified by the --user option, or the user called
"distcc", or the user called "nobody".

distccd does not have a configuration file; it's behaviour is controlled only by command-
line options and requests from clients.

STANDALONE SERVER

       The recommended method for running distccd is as a standalone server.  distccd will listen
       for network connections and fork several child processes to serve them.

       If you installed distcc using a packaged version you may be able to start the server using
       the standard mechanism for your operating system, such as

              # service distcc start

       To  start  distccd  as  a standalone service, run a command like this either as root or an
       ordinary user:

              # distccd --daemon

RUNNING FROM INIT

       distccd may be run as a standalone daemon  under  the  control  of  another  program  like
       init(8)  or  daemontools.   The  super-server  starts  distccd  when the system boots, and
       whenever it exits.

       distccd should be started just as for a standalone server,  except  that  the  --no-detach
       option should be used so that the super-server can monitor it.

       For example, to add distccd as a process to Linux sysvinit, add this line to /etc/inittab

              dscc:2345:respawn:/usr/local/bin/distccd --verbose --no-detach --daemon

RUNNING FROM INETD

       distccd  may be started from a network super-server such as inetd or xinetd.  In this case
       inetd listens for network connections and invokes distccd when one arrives.

       This is slightly less efficient than running a standalone distccd daemon.  distccd is  not
       able  to  regulate  the  number of concurrent jobs accepted, but there may be an option in
       your inetd configuration to do so.

       For traditional Unix inetd, a line like this can be added to /etc/inetd.conf:

              distcc stream tcp nowait.6000 root /usr/local/bin/distccd distccd --inetd

       inetd imposes a limit on  the  rate  of  connections  to  a  service  to  protect  against
       accidental  or  intentional  overuse.  The default in Linux NetKit inetd is 40 per minute,
       which is far  too low for distccd.  The .6000 option raises the limit to 6000 per minute.

TERMINATING DISTCCD

       To shut down a standalone server, send a SIGTERM signal to the parent process.   The  most
       reliable  way  to  do  this  from  a  script is to use the --pid-file option to record its
       process ID.  Shutting down the server in this way  should  allow  any  jobs  currently  in
       progress to complete.

OPTIONS

--help Display summary usage information.

--version
Shows the daemon version and exits.

-j, --jobs JOBS
Sets a limit on the number of jobs that can be accepted at any time. By default
this is set to two greater than the number of CPUs on the machine, to allow for
some processes being blocked on network IO. (Daemon mode only.)

-N, --nice NICENESS
Makes the daemon more nice about giving up the CPU to other tasks on the machine.
NICENESS is an increment to the current priority of the process. The range of
priorities depends on the operating system but is typically 0 to 20. By default
the niceness is increased by 5.

-p, --port PORT
Set the TCP port to listen on, rather than the default of 3632. (Daemon mode
only.)

--listen ADDRESS
Instructs the distccd daemon to listen on the IP address ADDRESS. This can be
useful for access control on dual-homed hosts. (Daemon mode only.)

-P, --pid-file FILE
Save daemon process id to file FILE. (Daemon mode only.)

--user USER
If distccd gets executed as root, change to user USER.

-a, --allow IPADDR[/MASK]
Instructs distccd to accept connections from the IP address IPADDR. A CIDR mask
length can be supplied optionally after a trailing slash, e.g. 192.168.0.0/24, in
which case addresses that match in the most significant MASK bits will be allowed.
If no --allow options are specified, distccd will exit immediately! Unauthorized
connections are rejected by closing the TCP connection immediately. A warning is
logged on the server but nothing is sent to the client.

--job-lifetime SECONDS
Kills a distccd job if it runs for more than SECONDS seconds. This prevents denial
of service from clients that don't properly disconnect and compilers that fail to
terminate. By default this is turned off.

--no-detach
Do not detach from the shell that started the daemon.

--no-fork
Don't fork children for each connection, to allow attaching gdb. Don't use this if
you don't understand it!

--log-file FILE
Send messages to file FILE instead of syslog. Logging directly to a file is
significantly faster than going via syslog and is recommended.

--log-level LEVEL
Set the minimum severity of error that will be included in the log file. Useful if
you only want to see error messages rather than an entry for each connection.
LEVEL can be any of the standard syslog levels, and in particular critical, error,
warning, notice, info, or debug.

--log-stderr
Send log messages to stderr, rather than to a file or syslog. This is mainly
intended for use in debugging. Do not use in inetd mode.

--verbose
Include debug messages in log. Equivalent to --log-level=debug

--wizard
Turn on all options appropriate for starting distccd under gdb: run as a daemon,
log verbosely to stderr, and do not detach or fork. For wizards only.

--stats
Turn on the statistics HTTP server. By default it is off. (Daemon mode only.)

--stats-port PORT
Set the TCP port to listen on for HTTP requests, rather than the default of 3633.
(Daemon mode only.)

--inetd
Serve a client connected to stdin/stdout. As the name suggests, this option should
be used when distccd is run from within a super-server like inetd. distccd assumes
inetd mode when stdin is a socket.

--daemon
Bind and listen on a socket, rather than running from inetd. This is used for
standalone mode. distccd assumes daemon mode at startup if stdin is a tty, so
--daemon should be explicitly specified when starting distccd from a script or in a
non-interactive ssh connection.

--zeroconf
Register the availability of this distccd server using Avahi Zeroconf DNS Service
Discovery (DNS-SD). This allows distcc clients on the local network to access this
distccd server without explicitly listing its host name or IP address in their
distcc host list: the distcc clients can just use "+zeroconf" in their distcc host
lists. This option is only available if distccd was compiled with Avahi support
enabled.

SEARCH PATHS

       distcc  can  pass  either  a relative or an absolute name for the compiler to distccd.  If
       distcc is given an explicit absolute compiler filename, that name is used verbatim on both
       the  client and server.  If the compiler name is not an absolute path, or if the client is
       used in masquerade mode, then the server's PATH is searched.

       distccd inherits its search path from its parent process.  By  default  distccd  tries  to
       remove  directories  that  seem  to  contain  distccd  masquerade  links, to guard against
       inadvertent recursion.  The DISTCCD_PATH environment variable may be used to set the path.

       The search path is logged when --verbose is given.  In case of confusion, check the logs.

       When distccd is run over ssh, the $HOME/.ssh/environment file may be useful in setting the
       path.  See ssh(1).

DIAGNOSTICS

       distccd  logs  messages  to  syslog's daemon facility by default, which normally writes to
       /var/log/daemon or /var/log/messages.  Log messages can be sent to a different file  using
       the --log-file option.

ENVIRONMENT VARIABLES

       DISTCC_CMDLIST
              If  the  environment  variable  DISTCC_CMDLIST  is  set,  load  a list of supported
              commands from the file named by DISTCC_CMDLIST, and refuse  to  serve  any  command
              whose  last DISTCC_CMDLIST_MATCHWORDS last words do not match those of a command in
              that list.  See the comments in src/serve.c.

       DISTCC_CMDLIST_NUMWORDS
              The number of words, from the end of the command, to match. The default is 1.

       DISTCCD_PATH
              When starting distccd, if this value is set it  will  be  used  unaltered  for  the
              command-execution  PATH.   The  code  that  normally  tries  to  remove  masquerade
              directories from the path is skipped.

       DISTCC_SAVE_TEMPS
              If set to 1, temporary files are not deleted after use.

       Note that DISTCC_LOG does not affect the log destination for the server.

       DISTCC_TCP_DEFER_ACCEPT
              On Linux, turn on the TCP_DEFER_ACCEPT socket option.  Defaults to on.

       TMPDIR Directory for temporary files such as preprocessor output.   By  default  /tmp/  is
              used.

BUGS

       IP-based access control is not secure against attackers able to spoof TCP connections, and
       cannot discriminate different users on a client.

       TCP  connections  are  not  secure  against  attackers  able  to observe or modify network
       traffic.

       Because ccache does not cache compilation from .i files, it is not useful to call it  from
       distccd.

LICENCE

       You  are  free  to  use distcc.  distcc (including this manual) may be copied, modified or
       distributed only under the terms of the GNU General Public Licence  version  2  or  later.
       distcc  comes  with  absolutely  no  warrany.   A  copy of the GPL is included in the file
       COPYING.

AUTHOR

       distcc was written by Martin Pool <mbp@sourcefrog.net>,  with  the  co-operation  of  many
       scholars  including Wayne Davison, Frerich Raabe, Dimitri Papadopoulos and others noted in
       the NEWS file.  See distcc-pump(1) for the authors of pump mode.  Please  report  bugs  to
       <distcc@lists.samba.org>.

                                           9 June 2008                                 distccd(1)