Security Tip: You can use Ethernet monitoring and diagnostic software like "Ethereal" (which has recently been renamed "WireShark") to snoop on all of the Ethernet traffic headed into, through, or out of an Ethernet Hub.

You might want to collect an Ethernet Hub for this purpose, inserting it between your NAT router and the Cable or DSL modem leading to your Internet Service Provider. Then, anytime you want to investigate suspicious traffic headed into our out of your network, you can tap in with a simple Ethernet cable and take a detailed look at the traffic.