Java - How to detect IP version

Question

I'm getting Client IP address via below method :

public static String getClientIpAddr(HttpServletRequest request) {       String ip = request.getHeader("X-Forwarded-For");       ...     return ip }  

Now I want to detect if it is an IPV4 or an IPV6.

Answer 1

You could create an InetAddress and check if it became an ipv4 or ipv6 instance

InetAddress address = InetAddress.getByName(ip); if (address instanceof Inet6Address) {     // It's ipv6 } else if (address instanceof Inet4Address) {     // It's ipv4 } 

It seems a bit awkward, though, and I hope there is a better solution.

Answer 2

If you are sure you're getting either an IPv4 or IPv6, you can try the following. If you have a DNS name then this will try to perform a lookup. Anyway, try this:

try {      InetAddress address = InetAddress.getByName(myIpAddr);      if (address instanceof Inet4Address) {         // your IP is IPv4     } else if (address instanceof Inet6Address) {         // your IP is IPv6     }  } catch(UnknownHostException e) {      //  your address was a machine name like a DNS name, and couldn't be found  }