4.3BSD-Tahoe/usr/man/cat8/rlogind.0

RLOGIND(8C)	    UNIX Programmer's Manual	      RLOGIND(8C)



NNAAMMEE
     rlogind - remote login server

SSYYNNOOPPSSIISS
     //eettcc//rrllooggiinndd [ --dd ]

DDEESSCCRRIIPPTTIIOONN
     _R_l_o_g_i_n_d is the server for the _r_l_o_g_i_n(1C) program.	The
     server provides a remote login facility with authentication
     based on privileged port numbers from trusted hosts.

     _R_l_o_g_i_n_d listens for service requests at the port indicated
     in the ``login'' service specification; see _s_e_r_v_i_c_e_s(5).
     When a service request is received the following protocol is
     initiated:

     1)   The server checks the client's source port.  If the
	  port is not in the range 0-1023, the server aborts the
	  connection.

     2)   The server checks the client's source address and
	  requests the corresponding host name (see
	  _g_e_t_h_o_s_t_b_y_a_d_d_r(3N), _h_o_s_t_s(5) and _n_a_m_e_d(8)).  If the
	  hostname cannot be determined, the dot-notation
	  representation of the host address is used.

     Once the source port and address have been checked, _r_l_o_g_i_n_d
     allocates a pseudo terminal (see _p_t_y(4)), and manipulates
     file descriptors so that the slave half of the pseudo termi-
     nal becomes the ssttddiinn ,, ssttddoouutt ,, and ssttddeerrrr for a login pro-
     cess.  The login process is an instance of the _l_o_g_i_n(1) pro-
     gram, invoked with the --rr option.	The login process then
     proceeds with the authentication process as described in
     _r_s_h_d(8C), but if automatic authentication fails, it
     reprompts the user to login as one finds on a standard ter-
     minal line.

     The parent of the login process manipulates the master side
     of the pseduo terminal, operating as an intermediary between
     the login process and the client instance of the _r_l_o_g_i_n pro-
     gram.  In normal operation, the packet protocol described in
     _p_t_y(4) is invoked to provide ^S/^Q type facilities and pro-
     pagate interrupt signals to the remote programs.  The login
     process propagates the client terminal's baud rate and ter-
     minal type, as found in the environment variable, ``TERM'';
     see _e_n_v_i_r_o_n(7).  The screen or window size of the terminal
     is requested from the client, and window size changes from
     the client are propagated to the pseudo terminal.

DDIIAAGGNNOOSSTTIICCSS
     All diagnostic messages are returned on the connection asso-
     ciated with the ssttddeerrrr, after which any network connections



Printed 7/9/88		  May 24, 1986				1






RLOGIND(8C)	    UNIX Programmer's Manual	      RLOGIND(8C)



     are closed.  An error is indicated by a leading byte with a
     value of 1.

     ````TTrryy aaggaaiinn..''''
     A _f_o_r_k by the server failed.

     ````//bbiinn//sshh:: ......''''
     The user's login shell could not be started.

BBUUGGSS
     The authentication procedure used here assumes the integrity
     of each client machine and the connecting medium.	This is
     insecure, but is useful in an ``open'' environment.

     A facility to allow all data exchanges to be encrypted
     should be present.

     A more extensible protocol should be used.





































Printed 7/9/88		  May 24, 1986				2