Provided by: kerberos4kth-servers_1.2.2-11.3ubuntu4_i386 bug


     rlogind - remote login server


     rlogind [-ailnkvxD] [-p portnumber] [-L /bin/login]


     Rlogind is the server for the rlogin(1) program.  The server provides a
     remote login facility with kerberos-based authentication or traditional
     pseudo-authentication with privileged port numbers from trusted hosts.

     Options supported by rlogind:

     -a      No-op.  For backwards compatibility.  Hostnames are always

     -l      Prevent any authentication based on the user’s “.rhosts” file,
             unless the user is logging in as the superuser.

     -n      Disable keep-alive messages.

     -k      Enable kerberos authentication.

     -i      Do not expect to be spawned by inetd and create a socket and
             listen on it yourself.

     -p -portnumber
             Specifies the port number it should listen on in case the

     -i      flag has been given.

     -v      Vacuous, echo "Remote host requires Kerberos authentication" and

     -x      Provides an encrypted communications channel.  This options
             requires the -k flag.

     -L -pathname
             Specify pathname to an alternative login program.

     -D      Use the TCP nodelay option (see setsockopt(2)).

     When a service request is received, rlogind verifies the kerberos ticket
     supplied by the user.

     For non-kerberised connections, 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(3), hosts(5) and
          named(8)).  If the hostname cannot be determined, the dot-notation
          representation of the host address is used.  The addresses for the
          hostname are requested, verifying that the name and address
          correspond.  Normal authentication is bypassed if the address
          verification fails.

     Once the source port and address have been checked, rlogind proceeds with
     the authentication process described in rshd(8).

     It then allocates a pseudo terminal (see pty(4)), 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 -f option if
     authentication has succeeded.  If automatic authentication fails, the
     user is prompted to log in as if 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(4) 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(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

     Transport-level keepalive messages are enabled unless the -n option is
     present.  The use of keepalive messages allows sessions to be timed out
     if the client crashes or becomes unreachable.


     All initial diagnostic messages are indicated by a leading byte with a
     value of 1, after which any network connections are closed.  If there are
     no errors before login is invoked, a null byte is returned as in
     indication of success.

     Try again.
             A fork by the server failed.


     login(1), ruserok(3), rshd(8)


     A more extensible protocol should be used.


     The rlogind command appeared in 4.2BSD.