Packet Smashing

Most local-area networks transmit data between computers in blocks called packets. Through a procedure called packet smashing, unauthorized users can harm or destroy data. Packet smashing involves capturing packets before they reach their destination, injecting arbitrary data into the contents, then sending the packets back on their original course. On a local-area network, packet smashing is impossible because packets reach all systems, including the server, at the same time. Packet smashing is possible on a gateway, however, so make sure all gateways on the network are protected.

The most dangerous attacks are those that affect the integrity of the data. Such attacks involve changing the contents of the packets or impersonating a user. Attacks that involve eavesdropping--recording conversations and replaying them later without impersonating a user--do not compromise data integrity. These attacks do affect privacy, however. You can protect the privacy of sensitive information by encrypting data that goes over the network.