jammy (8) xinetd.8.gz

Provided by: xinetd_2.3.15.3-1_amd64 bug

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  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 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.

       -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 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 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).

       SIGABRT        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

ENVIRONMENT

       REMOTE_HOST Contains the IP address of the client.

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)