Towards filtering and alerting rule rewriting on single-component policies

The use of firewalls and network intrusion detection systems (NIDSs) is the dominant method to survey and guarantee the security policy in current corporate networks. On the one hand, firewalls are traditional security components which provide means to filter traffic within corporate networks, as well as to police the incoming and outcoming interaction with the Internet, On the other hand, NIDSs are complementary security components used to enhance the visibility level of the network, pointing to malicious or anomalous traffic. To properly configure both firewalls and NIDSs, it is necessary the use of a set of configuration rules, i.e., a set of filtering or alerting rules. Nevertheless, the existence of anomalies within the set of configuration rules of both firewalls and NIDSs is very likely to degrade the network security policy. The discovering and removal of these anomalies is a serious and complex problem to solve. In this paper, we present a set of mechanisms for such a management.