Security & Privacy
Personal firewall advantages
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9 Oct 2003
Another thing a software firewall can do that a NAT router cannot is protect computers on your network from the other computers on your network.
If one of your computers gets compromised or infected, or if a user on your network decides to be malicious, a NAT router won’t help you one bit. Traffic between computers on your network doesn’t pass through NAT, so a worm on one computer can infect all the other computers. A hacker who gains access to you network can then attack any machine on your network. If you have a wireless access point on your network, anyone connecting to it is immediately behind your NAT router and can connect to your other computers.
A software firewall like ZoneAlarm, Outpost, or Norton Personal Firewall can prevent such intrusions from your own network.