ASP how to get the real IP address _asp Foundation

Use Request.ServerVariables ("REMOTE_ADDR") in the ASP to obtain the IP address of the client, but if the client is using a proxy server for access, then the IP address of the proxy server is taken, not the true client IP address. To obtain a client's real IP address through a proxy server, use Request.ServerVariables ("Http_x_forwarded_for") to read it.

However, it should be noted that not every proxy server can use Request.ServerVariables ("Http_x_forwarded_for") to read the real IP client, and some use this method to read the IP is still the proxy server.

It is also important to note that if the client is not accessed through a proxy server, the value taken with Request.ServerVariables ("Http_x_forwarded_for") will be empty. Therefore, if you want to use this method in your program, you can handle this:

......
Userip = Request.ServerVariables ("Http_x_forwarded_for")
If Userip = "" Then Userip = Request.ServerVariables ("REMOTE_ADDR")
......


That is: If the client through the proxy server, then take the value of http_x_forwarded_for, if not through the proxy server, take REMOTE_ADDR value.