Firewalls are hardware and software systems that protect a corporate network from attacks coming from the outside internet. There are several firewalls available in the market.Altough some firewalls are stronger then others with respect to some security or functionality aspects, they may be weaker in others. Therefore it becomes necessary to find testing methodology that will ease the process of firewall comparison. Performance, operating system, hardware and software building, ,etc., properties are important to develop testing methodology.