What are ICMP redirects and redirect bombs?
An ICMP Redirect tells the recipient system to over-ride something in its routing table. It is legitimately used by routers to tell hosts that the host is using a non-optimal or defunct route to a particular destination, i.e. the host is sending it to the wrong router. The wrong router sends the host back an ICMP Redirect packet that tells the host what the correct route should be. If you can forge ICMP Redirect packets, and if your target host pays attention to them, you can alter the routing tables on the host and possibly subvert the security of the host by causing traffic to flow via a path the network manager didn’t intend. ICMP Redirects also may be employed for denial of service attacks, where a host is sent a route that loses it connectivity, or is sent an ICMP Network Unreachable packet telling it that it can no longer access a particular network. Many firewall builders screen ICMP traffic from their network, since it limits the ability of outsiders to ping hosts, or modify th
An ICMP Redirect tells the recipient system to override something in its routing table. It is legitimately used by routers to tell hosts that the host is using a non-optimal or defunct route to a particular destination, i.e., the host is sending it to the wrong router. The wrong router sends the host back an ICMP Redirect packet that tells the host what the correct route should be. If you can forge ICMP Redirect packets, and if your target host pays attention to them, you can alter the routing tables on the host and possibly subvert the security of the host by causing traffic to flow via a path the network manager didn’t intend. ICMP Redirects also may be employed for denial of service attacks, where a host is sent a route that loses it connectivity, or is sent an ICMP Network Unreachable packet telling it that it can no longer access a particular network. Many firewall builders screen ICMP traffic from their network, since it limits the ability of outsiders to ping hosts, or modify th
