ASP. NET

We use request. servervariables ("remote_addr") to obtain the IP address of the client,

However, if the client is accessed by a proxy server, the IP address of the proxy server is obtained, rather than the real IP address of the client.

To obtain the real IP address of the client through the proxy server, use request. servervariables ("http_x_forwarded_for") to read.

However, not every proxy server can use request. servervariables ("http_x_forwarded_for") to read the real IP address of the client, some of which are still the IP address of the proxy server.

Note that if the client is not accessed through the proxy server, the value obtained using request. servervariables ("http_x_forwarded_for") will be null. Therefore, if you wantProgramYou can use this method as follows:

Userip = request. servervariables ("http_x_forwarded_for ")

If userip = "" Then userip = request. servervariables ("remote_addr"): If the client uses a proxy server, the value of http_x_forwarded_for is obtained.

/// <Summary> /// obtain the IP address /// </Summary> /// <returns> </returns> Public static string getipaddress () {string result = string. empty; Result = system. web. httpcontext. current. request. servervariables ["http_x_forwarded_for"]; // If a proxy is used, obtain the real IP address if (result! = NULL & result. indexof (".") =-1) // No "." is definitely not IPv4 format result = NULL; else if (result! = NULL) {If (result. indexof (",")! =-1) {// There are ",". Multiple proxies are estimated. Obtain the first IP address that is not an intranet IP address. Result = result. replace ("",""). replace ("'", ""); string [] temparyip = result. split (",;". tochararray (); For (INT I = 0; I <temparyip. length; I ++) {If (isipaddress (temparyip [I]) & temparyip [I]. substring (0, 3 )! = "10." & temparyip [I]. substring (0, 7 )! = "192.168" & temparyip [I]. substring (0, 7 )! = "1. 172.16. ") {return temparyip [I]; // find the address that is not the Intranet address} else if (isipaddress (result) // The proxy is the return result in IP format; else result = NULL; // the content in the proxy is not an IP address, take the IP address} If (null = Result | result = string. empty) Result = system. web. httpcontext. current. request. servervariables ["remote_addr"]; If (result = NULL | result = string. empty) Result = system. web. httpcontext. current. request. userhostaddress; return result ;} /// <summary> /// determine whether the IP address format is 0.0.0.0 // </Summary> /// <Param name = "str1"> IP address to be determined </param> /// <returns> true or false </returns> Private Static bool isipaddress (string str1) {If (str1 = NULL | str1 = string. empty | str1.length <7 | str1.length> 15) return false; string regformat = @ "^ \ D {1, 3} [\.] \ D {1, 3} [\.] \ D {1, 3} [\.] \ D {1, 3} $ "; RegEx = new RegEx (regformat, regexoptions. ignorecase); Return RegEx. ismatch (str1 );}

If the proxy server is not used, obtain the value of remote_addr.