


XINETD(8)						XINETD(8)


NAME
       xinetd - the extended Internet services daemon

SYNOPSIS
       xinetd [options]

DESCRIPTION
       xinetd performs the same function as inetd: it starts pro
       grams 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 ser
       vices, 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  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  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.

OPTIONS
       -d     Enables debug mode. This produces a lot  of  debug
	      ging  output,  and  it  makes  it possible to use a
	      debugger on xinetd.

       -syslog syslog_facility
	      This option enables syslog logging  of  xinetd-pro
	      duced 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.




			  28 April 1993				1





XINETD(8)						XINETD(8)


       -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  termi
	      nal.

       -f config_file
	      Determines the file that xinetd uses for configura
	      tion. The default is /etc/xinetd.conf.

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

       -loop rate
	      This  option sets the loop rate beyond which a ser
	      vice is considered in error and is deactivated. The
	      loop  rate  is  specified in terms of the number of
	      servers per second that can be forked  for  a  pro
	      cess.   The  speed  of  your machine determines the
	      correct value for this option.  The default rate is
	      10.

       -reuse If  this option is used, xinetd will set the socket
	      option  SO_REUSEADDR  before  binding  the  service
	      socket  to an Internet address. This allows binding
	      of the address even if there are programs that  use
	      it,  which  happens  when	 a  previous  instance of
	      xinetd has started some servers that are still run
	      ning.  This option has no effect on RPC services.

       -limit proc_limit
	      This option places a limit on the number of concur
	      rently 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 concur
	      rently  running  servers for remote userid acquisi
	      tion.

       -shutdownprocs limit
	      This option places a limit on the number of concur
	      rently running servers for service shutdown (forked
	      when the RECORD option is used).

       -cc interval
	      This option instructs xinetd  to	perform	 periodic
	      consistency  checks  on  its  internal  state every
	      interval seconds.




			  28 April 1993				2





XINETD(8)						XINETD(8)


       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.

       SIGUSR1	      causes a soft reconfiguration, which  means
		      that  xinetd rereads the configuration file
		      and adjusts accordingly.

       SIGUSR2	      causes a hard reconfiguration, which is the
		      same  as a soft reconfiguration except that
		      servers for services  that  are  no  longer
		      available are terminated. 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 arbitrar
		      ily 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 ser
		      vice will be  terminated;	 the  purpose  of
		      this  is to ensure that after a hard recon
		      figuration 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  ter
		      minating xinetd.

       SIGHUP	      causes  an internal state dump (the default
		      dump file is  /tmp/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 success
		      ful or not.

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




			  28 April 1993				3





XINETD(8)						XINETD(8)


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

PRONUNCIATION
       zy-net-d








































			  28 April 1993				4


