Getting IP address of client

Question

I am developing a web application using JSP, Servlets (Container: Glassfish) in which I need to get clients IP Address.

I am getting the clients IP address, because I want to give access to some pages (like Customer maintenance forms) only on computers withing the office, I want to restrict access to those pages outside office.

Following is my code so far:

way1

String ipAddress =  request.getRemoteAddr();
System.out.println("IP Address: "+ipAddress);

way2

String ipAddress=null;
String getWay = request.getHeader("VIA");   // Gateway
ipAddress = request.getHeader("X-FORWARDED-FOR");   // proxy
if(ipAddress==null)
{
    ipAddress = request.getRemoteAddr();
}
System.out.println("IP Address: "+ipAddress);

Above code gives me different IP Address each time when I restart my computer (Shutdown->Start or Restart).

I am getting IP6 like:

fe80:0:0:0:20ca:1776:f5ff:ff15%13

Let me know what is wrong with this code?

Answer 1

As @martin and this answer explained, it is complicated. There is no bullet-proof way of getting the client's ip address.

The best that you can do is to try to parse "X-Forwarded-For" and rely on request.getRemoteAddr();

public static String getClientIpAddress(HttpServletRequest request) {
    String xForwardedForHeader = request.getHeader("X-Forwarded-For");
    if (xForwardedForHeader == null) {
        return request.getRemoteAddr();
    } else {
        // As of https://en.wikipedia.org/wiki/X-Forwarded-For
        // The general format of the field is: X-Forwarded-For: client, proxy1, proxy2 ...
        // we only want the client
        return new StringTokenizer(xForwardedForHeader, ",").nextToken().trim();
    }
}

Answer 2

I use the following static helper method to retrieve the IP of a client:

public static String getClientIpAddr(HttpServletRequest request) {  
    String ip = request.getHeader("X-Forwarded-For");  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("Proxy-Client-IP");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("WL-Proxy-Client-IP");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_X_FORWARDED_FOR");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_X_FORWARDED");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_X_CLUSTER_CLIENT_IP");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_CLIENT_IP");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_FORWARDED_FOR");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_FORWARDED");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("HTTP_VIA");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getHeader("REMOTE_ADDR");  
    }  
    if (ip == null || ip.length() == 0 || ip.equalsIgnoreCase("unknown")) {  
        ip = request.getRemoteAddr();  
    }  
    return ip;  
}

Answer 3

I do like this,you can have a try

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;      
}   

Answer 4

As basZero mentioned, X-Forwarded-For should be checked for comma. (Look at : http://en.wikipedia.org/wiki/X-Forwarded-For). The general format of the field is: X-Forwarded-For: clientIP, proxy1, proxy2... and so on. So we will be seeing something like this : X-FORWARDED-FOR: 129.77.168.62, 129.77.63.62.

Answer 5

I believe it is more to do with how your network is configured. Servlet is simply giving you the address it is finding.

I can suggest two workarounds. First try using IPV4. See this SO Answer

Also, try using the request.getRemoteHost() method to get the names of the machines. Surely the names are independent of whatever IP they are mapped to.

I still think you should discuss this with your infrastructure guys.