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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.

       -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)

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

PRONUNCIATION
       zy-net-d

				 14 June 2001			     XINETD(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONTROLLING XINETD | FILES | SEE ALSO | AUTHOR | PRONUNCIATION

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