Protowall is a light firewall working in the background. It uses not enough means CPU (processor) and RAM (memory) and is able of blocking thousands of addresses IP.
Protowall works thanks to a driver filtering every packet, by extracting the letterhead IP and by comparing address with a list of blocked guests!
Note that main purpose of protowall is to block a mailing list IP definite.
It is based on a bad book of addresses IP called Bluetack Blacklists. She is managed thanks to another program, named Blocklist Manager.