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Basic info on how VPN works

Hi, Just wondering if you could kindly give me some basic information on how VPN work? How does each client know what decrypting key to use? Does the key remain the same all the time or does it change every time?

If the other client is not logged on does the information bounce back to the sender? Or is it stored somewhere until the other user logs on?

Your knowledge would be much appreciated, thank you.
Hi Dhillon,
Client encryption key lengths can be set manually through a configuration of the client or gateway, or they can be automatically negotiated whenever the client connects to a gateway.

The length of time the key is used is called the "crypto period." This is also something that can be set as a configuration parameter on your gateway. Normally, a client and gateway generate encryption keys each time the client connects. These are referred to as session keys. A gateway can also be configured to automatically regenerate keys ever so often, say every two hours.

If a client is not connected to the VPN, then it has no IP presence on the LAN behind the VPN gateway. In this case, traffic behaves in the same way it would if you unplugged a local computer.

This was last published in March 2003

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