Abstract: The conformance of a network to a set of security policy statements is determined by attempting to violate the policies by routing packets through models of network elements. Policy statements specify whether a set of clients is granted or denied access to a network service offered by a set of servers. Network element models are in accordance to the element's configurable parameters and supported services, which together indicate how the element will treat packets when the element's current configuration is applied to the model. Conformance to a policy statement is determined by building a packet in accordance with the network service and a representative network-element client and server, and by attempting to move the packet from the client to the server by applying the packet to the network element models. Policy conformance is based on whether the packet reaches the service on the server. Network reconfigurations are determined for non-conformant policies.