Refer to a class of remote tools in UNIX systems. The most popular are “rsh” for a remote shell, “rlogin” for a remote login, and
“rexec” for remote execution. These tools were very popular in the pre-Internet era because they were easy to
use and could be set up to automate a wide range of system administration
tasks. However, security for these tools was weak and data was sent across the
network in an unencrypted form. For these reasons, these tools have been widely
replaced by their cryptographic counterpart, ssh.