How a firewall works
|Article:HOWTO55054|||||Created: 2011-06-29|||||Updated: 2011-12-16|||||Article URL http://www.symantec.com/docs/HOWTO55054|
A firewall does all of the following tasks:
The firewall reviews the packets of data that travel across the Internet. A packet is a discrete chunk of data that is part of the information flow between two computers. Packets are reassembled at their destination to appear as an unbroken data stream.
Packets contain information about the following:
Ports are the channels that divide the stream of data that comes from the Internet. Applications that run on a computer listen to the ports. The applications accept the data that is sent to the ports.
Network attacks exploit weaknesses in vulnerable applications. Attackers use these weaknesses to send the packets that contain malicious programming code to ports. When vulnerable applications listen to the ports, the malicious code lets the attackers gain access to the computer.
Article URL http://www.symantec.com/docs/HOWTO55054