Including the reason for a port or host state

To make Nmap, include the reason why a port is marked as opened or closed and why the host is marked as alive; use the option --reason, as shown in the following command:

$ nmap --reason <target>

The option --reason will make Nmap include the packet type that determined the port and host state. We have the following example:

$ nmap --reason scanme.nmap.org
   Nmap scan report for scanme.nmap.org (74.207.244.221)
   Host is up, received echo-reply (0.12s latency).
   Not shown: 96 closed ports
   Reason: 96 resets
   PORT    STATE    SERVICE REASON
   22/tcp  open     sshsyn-ack
   25/tcp  filtered smtp    no-response
   80/tcp  open     http    syn-ack
   646/tcp filtered ldp     no-response
   Nmap done: 1 IP address (1 host up) scanned in 3.60 seconds