2. FIN Scan (-sF)

In Fin Scan technique, packets are sent with a Fin Flag. Sometimes, because of firewall, SYN Packets might be blocked. In such case, FIN Scan works by by passing the firewall. FIN packets are send to closed ports, if no response is received, it is because either the packet is dropped by firewall or the port is open.

Command: nmap -sU <target>