Using Netstat
Desktop Training - Ubuntu

Under the Netstat tab, you can take a look at routing table information. This can help you out if you have trouble connecting to either the Internet, or to other segments of your Local Area Network.

To use this, first click on the "Routing Table Information" button, and then click on the "Netstat" button on your right.

Use the "Active Network Services" option to see which ports are active. You can use this feature to help you plan a firewall configuration, or to help catch an intruder. (If you see an active port that you know shouldn't be active, there's a good chance that you're witnessing a break-in.)

This option give you information on any Multicast-capable network devices on your computer.