RLOGIND(1M)                                                        RLOGIND(1M)


NAME
     rlogind - remote login server

SYNOPSIS
     /usr/etc/rlogind [ -aln ]

DESCRIPTION
     Rlogind is the server for the rlogin(1C) program.  The server provides a
     remote login facility with authentication based on privileged port
     numbers from trusted hosts.  The -a option verifies the remote host name
     and address match on all incoming connections.  Normally this check is
     performed only for connections from hosts in the local domain.  The -l
     option disables validation using .rhosts files, unless the user is
     logging in as the superuser.  Transport-level keep-alive messages are
     enabled unless the -n option is present.  The use of keep-alive messages
     allows sessions to be timed out if the client crashes or becomes
     unreachable.  These options should specified in the /etc/inetd.conf file
     (see inetd(1M)).

     Rlogind listens for service requests at the port indicated in the
     ``login'' service specification; see services(4).  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 512-1023, the server aborts the connection.

     2)  The server checks the client's source address and requests the
         corresponding host name (see gethostbyaddr(3N), hosts(4) and
         named(1M)).  If the hostname is in the same domain as the server
         (according to the last two components of the domain name), or if the
         -a option is given, the addresses for the hostname are requested,
         verifying that the name and address correspond.  Address verification
         failures are logged with syslog(3B).  If the hostname cannot be
         determined or verified, the dot-notation representation of the host
         address is used for authentication.

     Once the source port and address have been checked, rlogind allocates a
     pseudo terminal (see pty(7M)), and manipulates file descriptors so that
     the slave half of the pseudo terminal becomes the stdin, stdout, and
     stderr for a login process.  The login process is an instance of the
     login(1) program, invoked with the -r or -R options.  The login process
     then proceeds with the authentication process as described in rshd(1M),
     but if automatic authentication fails, it reprompts the user to login as
     one finds on a standard terminal line.

     The parent of the login process manipulates the master side of the pseudo
     terminal, operating as an intermediary between the login process and the
     client instance of the rlogin program.  In normal operation, the packet
     protocol described in pty(7M) is invoked to provide ^S/^Q type facilities
     and propagate interrupt signals to the remote programs.  The login
     process propagates the client terminal's baud rate and terminal type, as
     found in the environment variable, ``TERM''; see environ(5).  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.

DIAGNOSTICS
     All diagnostic messages are returned on the connection associated with
     the stderr, after which any network connections are closed.  An error is
     indicated by a leading byte with a value of 1.

     ``Try again.''
     A fork by the server failed.

     ``/bin/sh: ...''
     The user's login shell could not be started.

BUGS
     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.


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