XINETD(8)		    System Manager's Manual		     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)