Firestarter is a good Graphic Personal Firewall utility in ubuntu,it helps to set up allow policies for incoming connections such as http and ssh.You don’t need it running because Linux has a built-in firewall and firestarter just configures it for you in a graphical way.
To install Firestarter, navigate to Applications–>Add/Remove.Select “All available applications”in “Show”,search “firestarter”.Check Firestarter in the screen and click on Apply Changes.
To configure firestarter,open it up at System–>Administration–>Firestarter.
The first time you start Firestarter, a Wizard will appear to you.Click the “Forward” button until finish,don’t check “internet connection sharing”.
When firestarter starts up,click Preferences button.Check all checkboxes in “Interface”,”Policy”,”Firewall” and check “Enable ICMP Filtering” in “ICMP Filtering”