Proxy and ip address

Hi everyone!

I trying to create a control panel for my website, obviously the security is important. Using the ip address allow me to know when the user is logon or logout, but I'm worry about people with behind proxy servers.

I love programing but sadly about networks... you know is better don't talk about it :)

My question is:

When Request.UserHostAddress is used I get the ip user address or ip proxy address? Will I get the same ip address for all user behind the proxy?


Thanks!
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