What is the port number for Telnet?

Telnet = port 23 (TCP).

Telnet = Port 23 (TCP)

Telnet provides unencrypted remote terminal access.

Security warning: Telnet sends passwords in plaintext! Always use SSH (port 22) instead.

Memory tip: Telnet (23) is right after SSH (22) - think "SSH first, Telnet if you must (but don't!)."

Go deeper:

• Telnet — Wikipedia overview confirming TCP port 23 and why its plaintext transport is insecure.
• List of TCP and UDP port numbers — the broader lookup table placing 23 among the well-known ports.