|  |  | There are numerous firewalls on the market today, and each one has its own individual characteristics. Some are faster than others, and some filter at different layers. Firewalls also have varying degrees of complexity and operational difficulty. The following is a partial list of firewalls: Cisco IOS Firewall is an inexpensive way to upgrade a Cisco router to provide powerful firewall and intrusion detection system software. Cisco IOS Firewall has 59 different network attack signatures. Cisco PIX Firewall is a hardware and software solution. Checkpoint Firewall One is software that runs on UNIX or NT. Raptor Eagle software also runs on UNIX or NT, as does Network Associates Gauntlet.