The Difference Between A Shared Key and Open System?

[Pablo72]

I did post this in the Network forum, but it seems a bit quiet in there, so I thought I would try my luck with you techno wizards!!!!!

Might sound like a basic question... but I'm a basic kinda guy!

What is the difference between a Shared Key and an Open System when using WEP on a wireless set-up?

Cheers