1. To perform active OS fingerprinting, use Nmap's "-O" flag followed by the target IP address. This sends probe packets to the target and analyzes the responses to determine the operating system.
2. For passive fingerprinting, sniff the network traffic without making contact with targets. Analyze characteristics like TCP/IP stack implementation to fingerprint operating systems.
3. Nmap is a useful tool for active fingerprinting as it has a large database of OS fingerprints. Passive fingerprinting can be done using a network sniffer without alerting targets. Both methods provide ways to remotely determine operating systems without access to