May 26, 2018
Remote firewall auditing tool
Firewalk is a network auditing tool that attempts to determine what transport protocols a given gateway will pass. Firewalk works by sending out TCP or UDP packets with a TTL one greater than the targeted gateway. If the gateway allows the traffic, it will forward the packets to the next hop where they will expire and elicit an ICMP_TIME_EXCEEDED message. If the gateway host does not allow the traffic, it will likely drop the packets on the floor and we will see no response.