1. A replay attack is a type of sniffer attack where the traffic is captured then retransmitted back at a computer. Analogy: In the 1992 movie Sneakers, the victim uses a voice identification system. Therefore, the heroes record the voice of one of the victim's employees, edit it with a computer, then play it back into the voice recognition system. Key point: It seems the first generation of any security architecture is vulnerable to replay attacks. For example, IPsec was original vulnerable to some replay attacks, even though it had provisions against the most obvious ones. Key point: The anti-replay remedy is to include a timestamp with a message. This then implies that everyone needs to have their clocks synchronized in order to communicate correctly. From Hacking-Lexicon

2. play back typescripts, using timing information From whatis