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XINETD(8)		    System Manager's Manual		     XINETD(8)

       xinetd -	the extended Internet services daemon

       xinetd [options]

       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.

       -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 de-
	      fault is /etc/xinetd.conf.

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

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

	      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.

	      This option causes xinetd	to print out its version information.

	      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

       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. Ac-
		      cess 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 ac-
		      cess 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 running 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

       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

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

       /etc/xinetd.conf	   default configuration file
			   default dump	file




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


				 14 June 2001			     XINETD(8)


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