Only very few troubleshooting tools exist, that universally work on the public internet. Ping and traceroute are the ones that are most frequently used, when issues arise that are outside the user's administrative reach. Both perform quite basic checks. Ping can only confirm basic reachability of an interface. Traceroute can enumerate routers in the forward direction of a path but remains blind to the reverse path. In this memo, ICMP extensions are defined, that allow to build a reverse traceroute tool for the public internet.
