Difference between Internal IP Address and External IP Address

Question

Can anyone tell me what is difference between Internal IP Address and External IP Address? How to get both in any programming language like Java, C# or Adobe AIR?

Answer 1

Internal IP address is the address from your network:

IPHostEntry heserver = Dns.GetHostEntry(Dns.GetHostName());
IPAddress curAdd = heserver.AddressList[0];
curAdd.ToString();

Your external IP address is the address from your ISP

string ip = new 
     System.Net.WebClient()
      .DownloadString(("http://www.whatismyip.com/automation/n09230945.asp"));

Answer 2

You can use the following code (in java) to get the local IP address:

public String getLocalIpAddress() {
     try {
         for (Enumeration en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {
             NetworkInterface ni = en.nextElement();
             for (Enumeration enumIpAddr = ni.getInetAddresses(); enumIpAddr.hasMoreElements();) {
                 InetAddress inetAddress = enumIpAddr.nextElement();
                 if (!inetAddress.isLoopbackAddress()) { //ignore 127.0.0.1
                     return inetAddress.getHostAddress().toString();
                 }
             }
         }
     } catch (SocketException ex) {
     }
     return null;
 }