Data Navigation Protocol Attacks
These four protocols: IP, TCP, UDP, and ICMP are the basis for Internet communications. They are also the basis of many attacks that use the Internet or of attacks against the Internet itself.
For instance, setting the TTL counter to a high or infinite value causes bad packets to crash on indefinitely. This takes up bandwidth and clogs the pipes so other traffic can't get through. False ICMP messages can put the network on alert against threats that are not there, slowing or stopping communications, or causing unneeded reroutes. This can be particularly vexing when heavy traffic gets shipped down a narrow street. Network administrators will have a hard time limiting the flow without cutting off the desirable traffic.
TCP assures reliability by introducing sequence counters and acknowledgments to IP. Also, TCP transmissions proceed after the communicating systems give each other a handshake, that is, after both ends go through a short three-part exchange to confirm which other system they are talking with, similar to exchanging business cards before sitting down to make a deal. A favorite hacker trick is to open up a session (begin a communication) with a system under attack, receive an acknowledgment, and then leave the connection half-completed, tying up resources and memory on the attacked device. Do this enough times, and unprotected systems will buckle under the load, similar to meeting too many interesting people at one time at a party. Affected systems can hang up or cease functioning, denying services to legitimate users, or they can crash, possibly allowing attackers to modify the operating software with illicit changes that can create secret entrances to open the device to attackers.
Why is IP such a pushover? Because it is not being used for that which it was built. The military wanted a network protocol that would survive a worst case scenariosomething along the lines of global thermonuclear war. The network needed to pass traffic to every location smoothly and efficiently, and to be able to reconfigure itself around bad routes and sudden outages. Were the balloon to go up, and everyone except people in deep bunkers had to spend two weeks hiding in basements and under doors in slit trenches, while waiting for fallout to decay, the network was supposed to reconfigure itself and be ready to go once humanity reemerged, serving every place that was still a place.
Instead, the Internet became an "information superhighway" that led to economic growth, prosperity, and jobs. It became a tool of enhanced communications, helping to bring the entire human family closer together. True enough, there are robbers in the bushes around that highway, and attacks for money, both of the travelers and of the destinations, are increasingly common. There is also increasing concern about pedophiles who use the Internet to form associations with unsupervised innocents. These are unintended consequences against which the Internet was never fortified.