.\" Copyright (c) 1983 Regents of the University of California.
.\" All rights reserved. The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\" @(#)rlogind.8 6.3 (Berkeley) %G%
rlogind \- remote login server
program. The server provides a remote login facility
with authentication based on privileged port numbers from trusted hosts.
listens for service requests at the port indicated in
the ``login'' service specification; see
When a service request is received the following protocol
The server checks the client's source port.
If the port is not in the range 0-1023, the server
The server checks the client's source address
and requests the corresponding host name (see
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,
allocates a pseudo terminal (see
and manipulates file descriptors so that the slave
half of the pseudo terminal becomes the
The login process is an instance of the
program, invoked with the
option. The login process then proceeds with the authentication
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 pseduo terminal, operating as an intermediary
between the login process and the client instance of the
program. In normal operation, the packet protocol described
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
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.
All diagnostic messages are returned on the connection
after which any network connections are closed.
An error is indicated by a leading byte with a value of 1.
The user's login shell could not be started.
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
A more extensible protocol should be used.