by SuperBonBon

UPNP™ NAT mappings

UPNPLib and automatic NAT mappings  > IGD explained 

UPNPLib and automatic NAT mappings

The library provides an implementation of an Internet Gateway Device. With this class you can easily, open/close/check status of NAT ports mappings for all IGD UPNP devices on your network.

IGD explained

The class to use is net.sbbi.upnp.impls.InternetGatewayDevice. Here is a small code snipet (maps port 9090 for TCP on first IGD found and close immediatly the port) to see it in action :

      int discoveryTimeout = 5000; // 5 secs to receive a response from devices
      try {
        InternetGatewayDevice[] IGDs = InternetGatewayDevice.getDevices( discoveryTimeout );
        if ( IGDs != null ) {
          // let's the the first device found
          InternetGatewayDevice testIGD = IGDs[0];
          System.out.println( "Found device " + testIGD.getIGDRootDevice().getModelName() );
          // now let's open the port
          String localHostIP = InetAddress.getLocalHost().getHostAddress();
          // we assume that localHostIP is something else than 127.0.0.1
          boolean mapped = testIGD.addPortMapping( "Some mapping description", 
                                                   null, 9090, 9090,
                                                   localHostIP, 0, "TCP" );
          if ( mapped ) {
            System.out.println( "Port 9090 mapped to " + localHostIP );
            // and now close it
            boolean unmapped = testIGD.deletePortMapping( null, 9090, "TCP" );
            if ( unmapped ) {
              System.out.println( "Port 9090 unmapped" );
            }
          }
        }
      } catch ( IOException ex ) {
        // some IO Exception occured during communication with device
      } catch( UPNPResponseException respEx ) {
        // oups the IGD did not like something !!
      }
      

As you can see the code is quite easy to write.