Nimda does its scanning using regular HTTP (TCP port 80) (For more information on ports, go to: Explanation of ports). Thus, if your machines are not public Web servers, you could/should filter that traffic. For machines that are public Web servers, you obviously cannot do that.
Dig deeper on Security Resources
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.