Firewall is a useful technique that ensures network security. Firewall examines network packets and determines whether to accept or deny them based on an ordered set of filters. If anomalies, such as no packets reach to a server in a local network, which is protected by an individual firewall or by the most downstream firewall of hierarchical structure firewalls, exist in local network, an administrator wants to know which filters cause the anomalies. For this reason, it is necessary to search filters related to the server from individual or hierarchical firewalls and decide which filters are intrinsically executed to deal with packets. Since firewall policy consists of a lot of filters, and the behavior of this sequence of filters is too complicate to understand, an administrator is difficult to search some certain filters from firewall policies and decide which filters are really executed to deal with packets. In this paper, we propose a filter reverse search system to help the admi...