4.3BSD - /usr/man/cat8/inetd.0

INETD(8)                                                              INETD(8)


NAME
       inetd - internet ‘‘super-server’’

SYNOPSIS
       /etc/inetd [ -d ] [ configuration file ]

DESCRIPTION
       Inetd should be run at boot time by /etc/rc.local.  It then listens for
       connections on certain internet sockets.  When a connection is found on
       one  of its sockets, it decides what service the socket corresponds to,
       and invokes a program to service the request.   After  the  program  is
       finished,  it  continues  to listen on the socket (except in some cases
       which will be described below).  Essentially, inetd allows running  one
       daemon to invoke several others, reducing load on the system.

       Upon  execution,  inetd reads its configuration information from a con‐
       figuration file which, by default, is /etc/inetd.conf.  There  must  be
       an  entry  for  each  field of the configuration file, with entries for
       each field separated by a tab or a space.  Comments are  denoted  by  a
       ‘‘#’’  at  the  beginning  of  a line.  There must be an entry for each
       field.  The fields of the configuration file are as follows:
            service name
            socket type
            protocol
            wait/nowait
            user
            server program
            server program arguments

       The service name entry is the name of  a  valid  service  in  the  file
       /etc/services/.   For ‘‘internal’’ services (discussed below), the ser‐
       vice name must be the official name of the service (that is, the  first
       entry in /etc/services).

       The  socket  type  should  be  one  of  ‘‘stream’’, ‘‘dgram’’, ‘‘raw’’,
       ‘‘rdm’’, or ‘‘seqpacket’’, depending on whether the socket is a stream,
       datagram,  raw, reliably delivered message, or sequenced packet socket.

       The protocol must be a  valid  protocol  as  given  in  /etc/protocols.
       Examples might be ‘‘tcp’’ or ‘‘udp’’.

       The  wait/nowait  entry  is  applicable to datagram sockets only (other
       sockets should have a ‘‘nowait’’ entry in this space).  If  a  datagram
       server  connects  to its peer, freeing the socket so inetd can received
       further messages on the socket, it is said to be  a  ‘‘multi-threaded’’
       server,  and  should  use  the  ‘‘nowait’’ entry.  For datagram servers
       which process all incoming datagrams on a socket  and  eventually  time
       out,  the  server  is  said  to be ‘‘single-threaded’’ and should use a
       ‘‘wait’’ entry.  ‘‘Comsat’’ (‘‘biff’’) and ‘‘talk’’ are  both  examples
       of  the latter type of datagram server.  Tftpd is an exception; it is a
       datagram server that establishes pseudo-connections.  It must be listed
       as  ‘‘wait’’  in  order  to  avoid  a  race; the server reads the first
       packet, creates a new socket, and then forks and exits to  allow  inetd
       to check for new service requests to spawn new servers.

       The  user  entry  should  contain the user name of the user as whom the
       server should run.  This allows for servers to be given less permission
       than root.  The server program entry should contain the pathname of the
       program which is to be executed by inetd when a request is found on its
       socket.   If  inetd provides this service internally, this entry should
       be ‘‘internal’’.

       The arguments to the server program should be  just  as  they  normally
       are,  starting  with argv[0], which is the name of the program.  If the
       service is provided internally, the word ‘‘internal’’ should  take  the
       place of this entry.

       Inetd  provides  several ‘‘trivial’’ services internally by use of rou‐
       tines within itself.  These services are ‘‘echo’’, ‘‘discard’’, ‘‘char‐
       gen’’  (character  generator),  ‘‘daytime’’  (human readable time), and
       ‘‘time’’ (machine readable time, in the form of the number  of  seconds
       since midnight, January 1, 1900).  All of these services are tcp based.
       For details of these services, consult the  appropriate  RFC  from  the
       Network Information Center.

       Inetd  rereads its configuration file when it receives a hangup signal,
       SIGHUP.  Services may be added, deleted or modified when the configura‐
       tion file is reread.

SEE ALSO
       comsat(8C),  ftpd(8C),  rexecd(8C), rlogind(8C), rshd(8C), telnetd(8C),
       tftpd(8C)


4.3 Berkeley Distribution        May 26, 1986                         INETD(8)