PeerGuardian 2 is Phoenix Labs’ premier IP blocker for Windows. PeerGuardian 2 integrates support for multiple lists, list editing, automatic updates, and blocking all of IPv4 (TCP, UDP, ICMP, etc), making it the safest and easiest way to protect your privacy on P2P

PeerGuardian is an open source IP filter that is designed to block the IP addresses of certain organizations and corporations that may wish to harm a users privacy while using the Internet and peer-to-peer networks.

PeerGuardian 2 requires no driver installation, yet blocks IP addresses at a far higher speed than was previously available - never above 1% CPU on most test systems. On Windows 2000 and greater PeerGuardian 2 blocks at a kernel level, acting against every protocol used within the windows system. On Windows 98 or Me it blocks TCP only (due to technical reasons, kernel blocking in 98/ME is not feasible) with the same high performance of the Windows 2000 version.