Identifying the operating system

After identifying the open ports on the web server, you need to determine the underlying operating system. Nmap provides several options to do so. The OS scan is performed using the -O option; you can add -v for a verbose output to find out the underlying tests done to determine the operating system:


A skilled hacker does not rely on the results of a single tool. Therefore, Kali Linux comes with several fingerprinting tools; in addition to running your version scan with Nmap, you can get a second opinion using a tool such as Amap.