ASP network programming: How ASP obtains the client real IP address

To obtain the real IP address of the client through the proxy server, it is necessary to use Request.ServerVariables ("Http_x_forwarded_for") to read. However, it is important to note that not every proxy server can use Request.ServerVariables ("Http_x_forwarded_for") to read the client's real IP, some of which are read by this method is still 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 do 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 the value of REMOTE_ADDR.

' General function: If the client's real IP cannot be taken, the proxy IP of the client will be taken

Private Function GetIP ()

Dim stripaddr

If Request.ServerVariables ("http_x_forwarded_for") = "" OR InStr (Request.ServerVariables ("Http_x_forwarded_for"), " Unknown ") > 0 Then

STRIPADDR = Request.ServerVariables ("REMOTE_ADDR")

ElseIf InStr (Request.ServerVariables ("Http_x_forwarded_for"), ",") > 0 Then

STRIPADDR = Mid (Request.ServerVariables ("Http_x_forwarded_for"), 1, InStr (Request.ServerVariables ("HTTP_X_ Forwarded_for "),", ")-1)

ElseIf InStr (Request.ServerVariables ("Http_x_forwarded_for"), ";") > 0 Then

STRIPADDR = Mid (Request.ServerVariables ("Http_x_forwarded_for"), 1, InStr (Request.ServerVariables ("HTTP_X_ Forwarded_for "),"; ") -1)

Else

STRIPADDR = Request.ServerVariables ("Http_x_forwarded_for")

End If

GetIP = Trim (Mid (stripaddr, 1, 30))

End Function

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ASP network programming: How ASP obtains the client real IP address