Firewall is basically a security solution designed so as to protect the LAN(Private Network) and give half access to public users (DMZ).It basically monitors the packets that are going in and out of the network with the intention to block the malicious and undesirable traffic with an assumption that it might harm the network.The Firewall is basically commanded in the form of policies that are basically in the form of input given by the network administrators and henceforth are present and maintained in the rulebase irrespective of whether the firewall is software based or hardware based.To help ensure the effectiveness of the firewall it is necessary to optimize the firewall policy base and to test before deploying the firewall in the network.