RLOGIND(8)

NAME
rlogind, in.rlogind - remote login server

SYNOPSIS
login stream tcp nowait root /usr/sbin/in.rlogind in.rlogind
tcpd login /usr/sbin/in.rlogind

DESCRIPTION
Rlogind is the server for the rlogin(1) program. The server provides a remote login facility with authentication based on privileged port numbers from trusted hosts.

Rlogind listens for service requests at the port indicated in the ``login'' service specification; see services(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 gethostbyaddr(3), hosts(5) and named(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, rlogind allocates a pseudo terminal (see tty(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 -r option. The login process then proceeds with the authentication process as described in rshd(8), 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 rlogin program. In normal operation, the packet protocol described in tty(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 terminal.

SEE ALSO
rlogin(1).

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.