it's usefull for discover firewall rules using an IP TTL expiration technique known as firewalking.
Example Usage
nmap --script=firewalk --traceroute <host>
nmap --script=firewalk --traceroute --script-args=firewalk.max-retries=1 <host>
nmap --script=firewalk --traceroute --script-args=firewalk.probe-timeout=400ms <host>
nmap --script=firewalk --traceroute --script-args=firewalk.max-probed-ports=7 <host>
Download : Nmap Firewalk Script


