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XINETD(8)							     XINETD(8)



NAME
       xinetd - the extended Internet services daemon

SYNOPSIS
       xinetd [options]

DESCRIPTION
       xinetd  performs	 the  same  function as inetd: it starts programs that
       provide Internet services.  Instead of having such servers  started  at
       system  initialization  time, and be dormant until a connection request
       arrives, xinetd is the only daemon process started and  it  listens  on
       all  service  ports  for the services listed in its configuration file.
       When a request comes in, xinetd starts the appropriate server.  Because
       of  the	way it operates, xinetd (as well as inetd) is also referred to
       as a super-server.

       The services listed in xinetd's configuration  file  can	 be  separated
       into two groups.	 Services in the first group are called multi-threaded
       and they require the forking of a new server process for each new  con-
       nection	request.   The	new  server then handles that connection.  For
       such services, xinetd keeps listening for new requests so that  it  can
       spawn  new  servers.  On the other hand, the second group includes ser-
       vices for which the service daemon is responsible for handling all  new
       connection  requests.   Such  services  are  called single-threaded and
       xinetd will stop handling new requests for them until the server	 dies.
       Services in this group are usually datagram-based.

       So far, the only reason for the existence of a super-server was to con-
       serve system resources by avoiding to fork a  lot  of  processes	 which
       might  be  dormant  for	most of their lifetime.	 While fulfilling this
       function, xinetd takes advantage of the idea of a super-server to  pro-
       vide  features such as access control and logging.  Furthermore, xinetd
       is not limited to services listed in /etc/services.  Therefore, anybody
       can use xinetd to start special-purpose servers.

OPTIONS
       -d     Enables debug mode. This produces a lot of debugging output, and
	      it makes it possible to use a debugger on xinetd.

       -syslog syslog_facility
	      This option enables syslog logging of  xinetd-produced  messages
	      using  the  specified  syslog  facility.	The following facility
	      names are supported: daemon, auth, user, local[0-7] (check  sys-
	      log.conf(5)  for their meanings).	 This option is ineffective in
	      debug mode since all relevant messages are sent to the terminal.

       -filelog logfile
	      xinetd-produced  messages	 will be placed in the specified file.
	      Messages are always appended to the file.	 If the file does  not
	      exist,  it will be created.  This option is ineffective in debug
	      mode since all relevant messages are sent to the terminal.

       -f config_file
	      Determines the file that	xinetd	uses  for  configuration.  The
	      default is /etc/xinetd.conf.

       -pidfile pid_file
	      The  process  ID is written to the file. This option is ineffec-
	      tive in debug mode.

       -dontfork
	      Tells xinetd to stay in the  foreground  rather  than  detaching
	      itself,  to  support  being  run	from init or daemontools. This
	      option automatically sets -stayalive (see below).

       -stayalive
	      Tells xinetd to stay running even if no services are  specified.

       -limit proc_limit
	      This option places a limit on the number of concurrently running
	      processes that can be started by xinetd.	Its purpose is to pre-
	      vent process table overflows.

       -logprocs limit
	      This option places a limit on the number of concurrently running
	      servers for remote userid acquisition.

       -version
	      This option causes xinetd to print out its version  information.

       -inetd_compat
	      This option causes xinetd to read /etc/inetd.conf in addition to
	      the standard xinetd config files.	 /etc/inetd.conf is read after
	      the standard xinetd config files.

       -cc interval
	      This  option  instructs  xinetd  to perform periodic consistency
	      checks on its internal state every interval seconds.

       The syslog and filelog options are  mutually  exclusive.	  If  none  is
       specified, the default is syslog using the daemon facility.  You should
       not confuse xinetd messages with messages related to  service  logging.
       The  latter  are logged only if this is specified via the configuration
       file.

CONTROLLING XINETD
       xinetd performs certain actions when it receives certain signals.   The
       actions	associated with the specific signals can be redefined by edit-
       ing config.h and recompiling.

       SIGHUP	      causes a hard reconfiguration, which means  that	xinetd
		      re-reads	the  configuration  file  and  terminates  the
		      servers for  services  that  are	no  longer  available.
		      Access  control is performed again on running servers by
		      checking the remote location, access  times  and	server
		      instances. If the number of server instances is lowered,
		      some arbitrarily picked servers will be killed  to  sat-
		      isfy  the	 limit; this will happen after any servers are
		      terminated because of failing  the  remote  location  or
		      access  time  checks.   Also,  if the INTERCEPT flag was
		      clear and is set, any running servers for	 that  service
		      will  be	terminated;  the  purpose of this is to ensure
		      that after a hard reconfiguration there will be no  run-
		      ning servers that can accept packets from addresses that
		      do not meet the access control criteria.

       SIGQUIT	      causes program termination.

       SIGTERM	      terminates  all  running	servers	  before   terminating
		      xinetd.

       SIGUSR1	      causes  an internal state dump (the default dump file is
		      /var/run/xinetd.dump; to change the filename, edit  con-
		      fig.h and recompile).

       SIGIOT	      causes  an internal consistency check to verify that the
		      data structures used by the program have not  been  cor-
		      rupted.	When the check is completed xinetd will gener-
		      ate a message that says if the check was	successful  or
		      not.

       On  reconfiguration  the log files are closed and reopened. This allows
       removal of old log files.

FILES
       /etc/xinetd.conf	   default configuration file
       /var/run/xinetd.dump
			   default dump file

SEE ALSO
       inetd(8),

       xinetd.conf(5),

       xinetd.log(5)

       http://cr.yp.to/daemontools.html

AUTHOR
       Panos Tsirigotis, CS Dept, University of Colorado, Boulder Rob Braun

PRONUNCIATION
       zy-net-d




				 14 June 2001			     XINETD(8)
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