16.7 Adding Advanced Rules

So far we have looked at rules to control only the type of traffic to block (incoming traffic on port 22 for example) regardless of the source or destination of the traffic. It is often the case, however, that rules will need to be defined to allow or deny traffic based on an IP address or range of IP addresses.

For the purposes of an example, assume that the local system has an IP address of 192.168.0.102. The firewall may be configured to only allow access on port 22 from a system with the IP address of, for example, 192.168.0.105. To achieve this, the From: field of the Advanced settings panel should be set to the IP address of the system from which the connection request is originating (in this case 192.168.0.105).

The To: fields provide the option to specify the IP address and port of the system to which the connection is being made. In this example this would be port 22 on the local system (192.168.0.102). The To: IP address is actually optional...