Dr.Morena is a tool to confirm the rule configuration of a Firewall.
The configuration of a Firewall is done by combining more than one rule. Sometimes a rule configuration may reside in a place other than the basic rule configuration place. In such a case, it is difficult to confirm whether it is an intended configuration by the system administrators. (Is an unnecessary hole open, or is a necessary hole open?) So, we developed a tool which checks the rule of a Firewall.
We prepare a computer which has two network interface for this tool. Then, each network interface is connected to each of the network interfaces on both sides of the Firewall. The packet the source IP address and the destination IP address is forged and sent to the Firewall from one network interface. The packet which passed through the Firewall is confirmed in the other network interface. The rule of the Firewall is confirmed from the packets which passed through the Firewall, and the packets which didn't pass.
This tool can check the rules without depending on the way of the Firewall is configures.
We made two modules which operated on Linux. The first module is a check engine, and the second module is a packet list making engine.
Checker, which is the check engine, makes the check packet according to given packet information, and sends and receives this packet. Also, the check engine confirms whether the packet passed through the firewall, and returns the checked result.
Ideally, it is good to be able to check all packets of all services from all Internet Protocol addresses to all Internet Protocol addresses when we check the rules of a firewall. However, it is impossible to check all packets in appropriate time. Therefore, it is necessary to check the firewall by using only some limited packets. However, efficiency is bad in the check which uses packets chosen at random. Then, it is necessary to check the firewall by using the packet intended for an important address and the service listed in the security policy etc. by priority.
ListMaker, which is the check packet list making engine, lists necessary packets for the check, from information classified according to the importance degree.
By Mitsu (Feb. 2001)