1. A method for generating a configuration file for at least one firewall in a network, said network including a plurality of hosts, said method comprising the steps of: receiving a definition for a plurality of roles that specify the ability of a host to send and receive packets, wherein each of said roles may be assigned to said hosts independently of a topology of said network, such that said hosts inherit said definitions associated with an assigned role; receiving an assignment of said roles to said hosts in said network; and generating rules for said hosts based on said assigned roles, said rules determining whether a packet is passed to a destination host.