Ensure rsh client is not installed - dpkg

Information

These legacy clients contain numerous security exposures and have been replaced with the more secure SSH package. Even if the server is removed, it is best to ensure the clients are also removed to prevent users from inadvertently attempting to use these commands and therefore exposing their credentials. Note that removing the rsh package removes the clients for rsh, rcp and rlogin.

Solution

Uninstall rsh using the appropriate package manager or manual installation:
yum remove rsh
apt-get remove rsh
zypper remove rsh

See Also

https://www.cisco.com/c/en/us/td/docs/security/firepower/623/configuration/guide/fpmc-config-guide-v623.html