(fīr´wâk-ing)
(n.) Developed by Mike Schiffman and David Goldsmith, a technique for testing the vulnerability of a
firewall and
mapping the
routers of a
network that sits behind a firewall. Firewalking is a method of disguising
port scans. In practical applications, firewalking is similar to
tracerouting and works by sending into the firewall
TCP or
UDP packets that have a
TTL set at one
hop greater than the targeted firewall. If the packet makes it through the gateway, it is forwarded to the next hop where the TTL equals zero and elicits a TTL "exceeded in transit" message, at which point the packet is discarded. Using this method, access information on the firewall can be determined if successive probe packets are sent.
Other forms: firewalk (v.)
