Ensure telnet server is not enabled

Information

The telnet protocol is insecure and unencrypted. The use of an unencrypted transmission medium could allow a user with access to sniff network traffic the ability to steal credentials. The ssh package provides an encrypted session and stronger security.

Solution

Comment out or remove any lines starting with telnet from /etc/inetd.conf and /etc/inetd.d/*.
Set disable = yes on all telnet services in /etc/xinetd.conf and /etc/xinetd.d/*.

See Also

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