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 connection 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 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 pro-
       vide features such as access control and logging.  Furthermore, xinetd is not limited to services listed in /etc/services.  Therefore, any-
       body 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 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 /etc/xinetd.conf.

       -pidfile pid_file
	      The process ID is written to the file. This option is ineffective 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 prevent
	      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
       editing config.h and recompiling.

       SIGHUP	      causes  a  hard reconfiguration, which means that xinetd re-reads the configuration file and terminates the servers for ser-
		      vices 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 termi-
		      nated; 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 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)