What is a null scan?

A null scan is a type of network scanning technique used to probe a target system for open ports without establishing a full TCP connection. It sends packets with no flags set, which can sometimes elicit a response from the target, indicating which ports are open or closed based on the responses received. This method is stealthier than traditional scans, making it harder for intrusion detection systems to detect, but it can be less reliable on modern systems that do not respond to such probes. Null scans can be useful for network reconnaissance in security assessments.