How to obtain real IP address with ASP

As we all know, in the ASP can use Request.ServerVariables ("REMOTE_ADDR") to obtain the IP address of the client, but if the client is using a proxy server to access, that is the proxy server IP address, Instead of the real 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.

Note, however, that not every proxy server can use Request.ServerVariables ("Http_x_forwarded_for") to read the client's real IP, some of this method is still read to the proxy server IP.

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.