We are blocking unused ports on our servers as part of our server hardening, when we block TCP port 23, what are we blocking?
A: FTP data transfer.
B: FTP control.
CBK 4: Communication and Network Security
Source: ThorTeaches.com practice tests
D: Telnet: Remote access over a network. Uses TCP port 23, all data is plaintext including usernames and passwords, should not be used. Attackers with network access can easily sniff credentials and alter data and take controls of telnet sessions.