Java Get IP Address sample _java

If the reverse proxy software is used, the http://192.168.1.110:2046/URL is reversed to the http://www.xxx.com/URL, with REQUEST.GETREMOTEADDR () Method gets the IP address: 127.0.0.1 or 192.168.1.110, not the real IP of the client.

After the agent, because the client and the service increased between the middle tier, so the server can not directly to the client IP, server-side applications can not directly by forwarding the requested address to return to the client. However, in the HTTP header message that forwards the request, the X-forwarded-for information is added. The server address used to track the original client IP address and the original client request. When we visit http://www.xxx.com/index.jsp/, actually not our browser actually accesses the index.jsp file on the server, but first by the proxy server to access the http://192.168.1.110:2046/ INDEX.JSP, the proxy server will return the results of the access to our browser, because it is the proxy server to access index.jsp, so index.jsp through REQUEST.GETREMOTEADDR () method to obtain the IP is actually the proxy server address, not the client's IP address.

Then you can get the client real IP address method one:

Copy Code code as follows:

Public String Getremortip (HttpServletRequest request) {
if (Request.getheader ("x-forwarded-for") = = null) {
return request.getremoteaddr ();
}
Return Request.getheader ("X-forwarded-for");
}

But when I visit http://www.xxx.com/index.jsp/, the IP address that is returned is always unknown, not 127.0.0.1 or 192.168.1.110 as shown above, and I visit http:// 192.168.1.110:2046/index.jsp, you can return the client's real IP address, write a method to verify. The reason is on squid. The squid.conf configuration file forwarded_for The default is on, if Forwarded_for is set to OFF: X-forwarded-for:unknown
Then you can get the client real IP address of the method two:

Copy Code code as follows:

Public String getipaddr (HttpServletRequest request) {

String IP = request.getheader ("X-forwarded-for");
if (IP = null | | ip.length () = = 0 | | "Unknown". Equalsignorecase (IP)) {
ip = Request.getheader ("Proxy-client-ip");
}
if (IP = null | | ip.length () = = 0 | | "Unknown". Equalsignorecase (IP)) {
ip = Request.getheader ("Wl-proxy-client-ip");
}
if (IP = null | | ip.length () = = 0 | | "Unknown". Equalsignorecase (IP)) {
ip = request.getremoteaddr ();
}
return IP;
}

However, if the adoption of multi-level reverse proxy, x-forwarded-for value and more than one, but a series of IP values, exactly which is the real user end of the real IP?

The answer is to take the first unknown valid IP string in x-forwarded-for.

Such as:

Copy Code code as follows:

x-forwarded-for:192.168.1.110, 192.168.1.120, 192.168.1.130, 192.168.1.100

User Real IP is: 192.168.1.110