Some embodiments provide a method for identifying unnecessary firewall rules for a distributed firewall of a logical network. The method identifies a firewall policy for network traffic of the logical network. The firewall policy includes a set of firewall rules. The method generates a set of data for implementing the firewall policy on a set of managed forwarding elements that implement the logical network. The method analyzes potential network traffic based on the generated set of data to identify a subset of unnecessary data. The method identifies a subset of unnecessary firewall rules of the set of firewall rules that corresponds to the subset of unnecessary data.