PeerGuardian 2 is an IP filtering software designed to block the IP addresses of specific organizations and companies that may wish to harm the user's privacy while using the Internet and peer-to-peer networks. Unlike its predecessor, it does not require the installation of any drivers and blocks IP addresses much faster than before. On Windows 2000 and above, it blocks at the kernel level, acting against all protocols used within the Windows system. On Windows 98 or Me, it blocks only TCP (due to technical reasons, kernel-level blocking on 98/ME is not feasible) with the same high performance as the Windows 2000 version.

PeerGuardian 2 blocks IP addresses based on a list of IP addresses collected by many methods. By default, it collects IP addresses from the Blocklist.org website. Blocklist.org is a website that allows users to interact with and block IP addresses of specific organizations and companies. It was founded in early 2005 by phoenixlabs.org and intended to be a platform-agnostic database using open-published formats.

The software is fully automatic. There is no need to install a driver; just run the program without visiting the control panel. The new startup wizard makes everything more straightforward than ever. More detailed settings can be configured from the interface, including logging and the ability to prevent websites from being blocked. It is possible to allow an individual IP address for some time or permanently, solving the problem of incorrect IP addresses. In addition, new management and reporting database systems allow users to play an active role in preventing friendly IPs from being blocked.

PeerGuardian 2 has been significantly improved compared to its predecessor and is very easy to use, thanks to its startup wizard. In addition, it features a revamped user interface and a history viewer that allows the user to search for lists by name, enable/disable lists without having to delete them, and use the list cache to reduce load times. It also includes an update tool that multitasks and can be canceled.

However, this version has some disadvantages. On Windows 98 or Me operating systems, it only blocks TCP, which means that other protocols will not be protected. In addition, some users have reported problems with error detection and slow IP blocking speed. Also, although PeerGuardian 2 offers the option to allow connections over HTTP, this can be unsafe if you are not sure that none of your P2P or insecure applications use those ports. Instead, it is better to allow specific IPs manually and do a proper investigation on any unknown IPs before allowing access.

Here is a summary of the main features of PeerGuardian 2:

• Blocks IP addresses of specific organizations and companies that may harm user privacy when using the Internet and peer-to-peer networks.
• No driver installation is required.
• Blocks IP addresses with high speed and low CPU usage.
• Acts at the kernel level on Windows 2000 and later operating systems.
• Allows blocking HTTP traffic on ports 80 and 433.
• Provides an easy-to-use interface with a "Protection" tab and a "Settings" tab.
• Users can temporarily or permanently allow specific IP addresses through a context menu.
• It provides a history viewer that allows users to view and manage allowed and blocked connections.
• It has an integrated update system that automatically downloads the latest block lists.
• It offers some advanced configuration options, including the option to enable logging and the opportunity to prevent certain websites from being blocked.
• Comes with several predefined block lists, such as advertising, bogons, educational institutions, gaming, government, P2P networks, phishing, and spam lists.
• Allows users to create and edit their block lists.
• It has a system tray version that allows users to control the program from the notification area.