Remote Shell

rsh ("remote shell") is a command line computer program which can execute shell commands as another user, and on another computer across a computer network. The remote system on which the rsh executes the command needs to be running the rshd daemon.

The rsh command shares the same name as another common UNIX utility, the restricted shell, which first appeared in PWB/UNIX; in System V Release 4, the restricted shell is often located at /usr/lib/rsh.

History

rsh originated as part of the BSD Unix operating system, along with rcp, as part of the rlogin package on 4.2BSD in 1983. rsh has since been ported to other operating systems.

Limitations

As described in the rlogin article, the rsh protocol is not secure for network use, because it sends unencrypted information over the network, among other reasons. Some implementations also authenticate by sending unencrypted passwords over the network. rsh has largely been replaced by the very similar ssh ("secure shell") program on untrusted networks like the internet.

Example

As an example of rsh use, the following executes the command "mkdir testdir" as user "remoteuser" on the computer "host.example.com": rsh -l remoteuser host.example.com "mkdir testdir"

After the command has finished rsh terminates. If no command is specified then rsh will log in on the remote system using rlogin. The network location of the remote computer is looked up using the Domain Name System.

Port number

rsh uses well-known port TCP 514.

References

* [http://unixhelp.ed.ac.uk/CGI/man-cgi?rsh rsh - remote shell] - rsh man page.
* [http://www.securityfocus.com/infocus/1490 Back to the Basics: Solaris and inetd.conf Part One]
* [http://the.earth.li/~sgtatham/putty/0.53b/htmldoc/Chapter7.html Plink - a part of the PuTTY suite of free tools which provides similar behaviour for MS Windows clients]