PeerBlock

PeerBlock was imagined as a totally new concept in personal computer protection. The security it provides comes from the fact that it blocks any connection to known bad peers. And by peers, the program understands hacked computers, spyware orientated servers, machines that monitor P2P activities, sent information, and undoubtedly important entire countries. In this way, prevention has been taken up to a new level, as no upcoming data or no one way connections to potentially dangerous servers will be possible anymore.

Working as an IP blocker, this firewall comes with a library of bad IP addresses and can be controlled by users by checking or un-checking a list of options. One downfall is the possible blocking of a website that is on the white list just because it is hosted on a server that has its IPs on the black list.