[ktpsns]

This won't enhance security, if your shell allows arbitrary commands. A firewall helps.

[augusto-moura]

Yes! Having netcat or telnet on the system already invalidates the disable

[jagged-chisel]

A reduction in malicious avenues is always welcome.

[tyingq]

A lot of things to chase though. Lots of installed-by-default stuff like Perl and Gawk do sockets.