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RedHat 9 (Linux i386) - man page for xinetd (redhat section 8)

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 ser-
       vices.  Instead of having such servers started at system initialization time, and be  dor-
       mant  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.  Ser-
       vices  in  the first group are called multi-threaded and they require the forking of a new
       server process for each new connection request.	The new server then handles that  connec-
       tion.  For such services, xinetd keeps listening for new requests so that it can spawn new
       servers.  On the other hand, the second group includes services for which the service dae-
       mon  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 conserve 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 provide 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 possi-
	      ble 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  syslog.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

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

	      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 prevent 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

       -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  con-
       figuration file.

       xinetd  performs certain actions when it receives certain signals.  The actions associated
       with the specific signals can be redefined by editing config.h and recompiling.

       SIGHUP	      causes a hard reconfiguration, which means that xinetd re-reads the config-
		      uration  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  satisfy  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 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 xinetd.

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

       SIGIOT	      causes  an  internal  consistency  check to verify that the data structures
		      used by the program have not been corrupted.  When the check  is	completed
		      xinetd  will  generate  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

       /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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