Common Personal Firewall Features:
» Hide the computer from port scans by not responding to unsolicited network traffic
» Regulate all outgoing and incoming Internet traffic
» Restrict unwanted network traffic from locally installed applications
» Alert the user about outgoing connection attempts
» Allows the user to control which programs can and cannot access the local network and/or Internet
» Monitor applications that are listening for incoming connections
» Provide the user with information about an application that makes a connection attempt
» Provide information about the destination server with which an application is attempting to communicate
Source: Personal firewall - Wikipedia, the free encyclopedia