RLOGIND(1M) — Series 300 and 800 Only

NAME

rlogind − remote login server

SYNOPSIS

/etc/rlogind

DESCRIPTION

Rlogind is the server for the rlogin(1) program; it provides a remote login facility with authentication based on privileged port numbers. Rlogind expects to be executed by the Internet daemon when it receives a service request at the port indicated in the services data base for “login” using the “tcp” protocol; see inetd(1M) and services(4).

When a service request is received, the following protocol is initiated by rlogind:

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

2) Rlogind checks the client’s source address. If the address is associated with a host for which no corresponding entry exists in /etc/hosts (see hosts(4)), then the server aborts the connection.

Once the source port and address have been checked, rlogind gets a pseudo-terminal (see pty(7)), and manipulates file descriptors so that the slave half of the pseudo-terminal becomes stdin, stdout, and stderr for an instance of login(1) invoked with the −r option. The login process then proceeds with the authentication process as described in hosts.equiv(4). If authentication fails, login prompts the user with the normal login sequence.

The rlogind 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. The packet protocol described in pty(7) is used to enable and disable flow control via CTRL-S/CTRL-Q under the direction of the program running on the slave side of the pseudo-terminal and to flush terminal output in response to interrupt signals. The login process sets the TERM environment variable to correspond to the client account’s baud rate and terminal type; see environ(5).

To start rlogind from the Internet daemon, the configuration file /etc/inetd.conf must contain an entry as follows:

login stream tcp nowait root /etc/rlogind rlogind

DIAGNOSTICS

Errors in establishing a connection cause an error message to be returned through the socket connection with a leading byte of 1, after which the network connection is closed. Any errors generated by the login process or its descendents are passed through by the server as normal communication.

Hostname for your address (<remote address>) unknown
The server was unable to find an entry in the host database file /etc/hosts matching the address of the client; see hosts(4).

Next step: Check your host’s address in /etc/hosts on the host where rlogind is executing.

fork: No more processes
The server was unable to fork a process to handle the incoming connection.

Next step: Wait a period of time and try again. If this message persists, then the server’s host may have runaway processes that are using all the entries in the process table.

All ptys on remote host in use
The server was unable to obtain a pseudo-terminal for use with the login process. Either all pseudo-terminals were in use, or the pty driver has not been properly set up; see pty(7).

Next step: Check the pty configuration of the host where rlogind executes.

Permission denied
The server denied access due to the fact that the client was not using a reserved port. This should only happen to interlopers trying to break into the system.

/bin/login: ...
The login program could not be started via exec(2) for the reason indicated.

Next step: Try to correct the condition causing the problem. If this message persists, contact your system adminstrator.

WARNINGS

The authentication procedure used here assumes the integrity of each host and the connecting medium. This is insecure, but is useful in an “open” environment. Note that passwords are sent unencrypted through the socket connection.

DEPENDENCIES

Implemented on the Series 300 and 800 only.

AUTHOR

UCB (University of California at Berkeley)

FILES

/etc/hosts.equiv list of equivalent hosts

$HOME/.rhosts user’s private equivalence list

Museum

Related Articles