One port to rule them all

You need to create a firewall rule to allow telnet traffic to pass through. What port should you open in your firewall rule?

A) tcp/20

B) tcp/21

C) tcp/23

D) tcp/25

E) Just open them all; most people on the Internet are very, very honest.

The answer: C) tcp/23

The telnet protocol normally communicates over TCP port 23.

Want to know more? Watch “Common Ports.”

The fundamental languages used over our computer networks are a standard set of protocols that are used around the world. In this video, you’ll learn about protocols and the set of standards associated with TCP/IP. You’ll also learn the essentials of TCP/IP and how subnetting can be used to build today’s modern networks.