_O_n_l_i_n_e _M_a_n_u_a_l        System Manager Commands            inetd(8c)



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     inetd - internet ``super-server''

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     ////eeeettttcccc////iiiinnnneeeettttdddd [----dddd] [_c_o_n_f_i_g_u_r_a_t_i_o_n-_f_i_l_e]

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     _I_n_e_t_d should be activated by the init proccess from the file
     /etc/inittab.  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, _i_n_e_t_d allows running one daemon to invoke
     several others, reducing load on the system.

     Upon execution, _i_n_e_t_d reads its configuration information
     from a configuration file which, by default, is
     /_e_t_c/_i_n_e_t_d._c_o_n_f.  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 _s_e_r_v_i_c_e _n_a_m_e entry is the name of a valid service in the
     file /_e_t_c/_s_e_r_v_i_c_e_s/.  For ``internal'' services (discussed
     below), the service name _m_u_s_t be the official name of the
     service (that is, the first entry in /_e_t_c/_s_e_r_v_i_c_e_s).

     The _s_o_c_k_e_t _t_y_p_e should be one of ``stream'', ``dgram'',
     ``raw'', ``rdm'', or ``seqpacket'', depending on whether the
     socket is a stream, datagram, raw, reliably delivered mes-
     sage, or sequenced packet socket.

     The _p_r_o_t_o_c_o_l must be a valid protocol as given in
     /_e_t_c/_p_r_o_t_o_c_o_l_s.  Examples might be ``tcp'' or ``udp''.

     The _w_a_i_t/_n_o_w_a_i_t 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 _i_n_e_t_d 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.  _T_f_t_p_d 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 _i_n_e_t_d to check for new service requests to spawn
     new servers.

     The _u_s_e_r 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 _s_e_r_v_e_r _p_r_o_g_r_a_m entry
     should contain the pathname of the program which is to be
     executed by _i_n_e_t_d when a request is found on its socket.
     _i_n_e_t_d allows for the first component of the pathname to be
     "$PU" (e.g. /$_P_U/_e_t_c/_f_t_p_d), which it then expands into the
     actual PU name.  If _i_n_e_t_d 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.

     _I_n_e_t_d provides several ``trivial'' services internally by
     use of routines within itself.  These services are ``echo'',
     ``discard'', ``chargen'' (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 Net-
     work Information Center.

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

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     System Manager Commands (8): comsat, ftpd, rexecd, rlogind,
     rshd, telnetd, tftpd

December 1990                      TX System Manager's Reference