rsh

Additional Notes

rsh (remote shell) executes a command on a remote host without establishing an interactive login session. It is part of the r-utilities suite and uses host-based authentication via /etc/hosts.equiv or .rhosts files.

Like other r-commands, rsh transmits all data including authentication tokens in cleartext. It does not provide encryption, making it unsuitable for use over untrusted networks. SSH should be used instead for all remote command execution.

Syntax

rsh [-dn] [-l username] hostname [command]

Parameters

• hostname: The remote host to connect to.
• username: The username to authenticate as on the remote host.
• command: The command to execute on the remote host.

Common Options

• -l username: Log in as the specified user.
• -d: Enable debug output on the socket.
• -n: Redirect stdin from /dev/null.
• -K: Disable Kerberos authentication.
• -x: Enable DES encryption (if compiled in).

Examples

rsh server01 df -h

Run df -h on server01 and display the output locally.

rsh -l admin backup-server "tar czf /backup/etc.tgz /etc"

Run a tar backup command as user admin on the remote host.

Practical Notes

• rsh is obsolete and insecure. Use ssh user@host command instead.
• The remote shell service runs on TCP port 514 via rshd or in.rshd.
• Authentication is based on IP address trust, which is trivially spoofed.
• Most distributions no longer ship an rsh server.
• The SSH equivalent is ssh user@host command.