"Ever wonder what ports are open on your Linux machine? Did
you ever want to know who was connecting to your machine and what
services were they connecting to? Netstat does just that."
"To take a look at all TCP ports that are open on you
The use of the '-n' option will give you numerical addresses
instead of determining the host. This speeds up the response of the
output. The '-l' option only shows connections which are in
"LISTEN" mode. And '-t' only shows the TCP connections."