chiawaikian
Joined: 18 Jan 2006
Posts: 207
Location: Singapore
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 Posted: 01/22/06 - 08:42 Post subject: Free and good software firewalls |
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There are many (65535!) virtual ports in a computer. These ports are either open, closed, or filtered (often called blocked or stealthed). Ports are generally open because they are held open by an application that is listening on that port. Most of these programs are servers. While most home users have little reason to run servers, by default Windows 2000 and XP runs several services which keep ports open.It must be also be noted that to run some programs like P2P sharing, some IM services or online gaming ports will also often have to be open. When such ports are open with applications listening behind them, a hacker has an opportunity to exploit weaknesses in the application to cause damage to your system. Similarly worms like Sasser exploit weaknesses found in windows services to spread by port scanning vulnerable machines on TCP 445.
To prevent these port scanning and other malicious attacks, a firewall should be installed. Firewalls act as a barrier between your PC and the Internet. They filter the data that is being transmitted and received. Also, unless otherwise configured, firewalls block all the open ports so that port scanning will be unsuccessful.
Free firewalls to use (install one only):
ZoneAlarm
OutPost Personal Firewall
Sunbelt Kerio Personal Firewall |
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