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1. Tiny Personal Firewall: This handy application gives you some control in determining how your applications transmit to the Web and receive data from it. The program offers high, medium, and low security levels. If you're not sure which to choose, don't worry: The program can operate in learning mode, letting you decide whether to deny or accept data in each situation. You can then establish rules to determine how you want to deal with similar situations in the future. This utility can check for digital signatures, and it can restrict applications to certain ports or destination IP addresses. You can also create reports of all intrusion attempts.

2. ZoneAlarm: If you have an "always-on" connection with a permanent IP address, your PC is especially vulnerable to hacker attacks. This free utility offers you some protection. You can block uninitiated and unwanted traffic, even while your PC is unattended or while you're not using your connection. You can also limit your exposure by specifying which applications can access the Internet. This update lets you stop e-mail-borne Visual Basic Script worms, such as the "ILove You" virus.

Note: This file is free for personal use; for business use it is $19.95.

3. NetWatcher 2000: This utility runs in the background while you are connected to the Internet, monitoring queries for information. If it detects one, it alerts you and gives you the option of immediately closing the connection. The program also logs the intruder's IP address, port number, and host, letting you report the intruder to their Internet service provider.

4. ConSeal PC Firewall: This personal firewall lets you create rule sets that dictate what data can access your PC. It protects you from Internet threats, as well as from applications on your network. The firewall lives beneath your operating system, and any offending packet or data is automatically dismissed. You can define what type of data you want to avoid, or you can put the firewall in learning mode, which will create a rule set based on your actions. If an unknown packet tries to access your PC, the program lets you know and waits for your permission. The program also includes a Whois link for retrieving remote-host information.

5. Sygate Personal Firewall: If you're concerned about unauthorized users accessing data on your PC, this program can give you an added line of defense, whether you run it automatically when Windows loads or whether you launch it from an icon in the system tray. The program features several security levels that alert you of possible intrusion. You can configure the program so that it alerts you of unauthorized activity but ignores inbound packets that you specifically request, such as Web pages or file downloads. You can also use this program in tandem with another firewall. This utility can create reports of all Internet activity, as well.