The daemon typically uses the well-known Transmission Control Protocol (TCP) port number 513.
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.
rsh has largely been replaced with the secure shell (ssh) program, even on local networks.
[1][2] As an example of rsh use, the following executes the command mkdir testdir as user remoteuser on the computer host.example.com running a UNIX-like system: After the command has finished rsh terminates.
The network location of the remote computer is looked up using the Domain Name System.