Java

Check Internet Connectivity

See more Socket/SSL/TLS Examples

Demonstrates an efficient way to test for Internet connectivity. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    CkSocket socket = new CkSocket();
    // 1. Use a reliable Anycast IP. 
    //    8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) are the industry standards.
    String targetIp = "8.8.8.8";

    // 2. Use Port 53 (DNS). 
    //    DNS servers typically listen on TCP Port 53 as well as UDP. 
    //    (Alternatively, use port 443 if you suspect port 53 is blocked).
    int port = 53;

    // 3. Disable SSL (0). 
    //    We are not doing a handshake, just a TCP connection.
    boolean ssl = false;

    // 4. Short Timeout (1500ms).
    //    If you can't reach Google in 1.5 seconds, the connection is 
    //    likely too poor for practical use anyway.
    int timeoutMs = 1500;

    // Connect
    success = socket.Connect(targetIp,port,ssl,timeoutMs);
    if (success == false) {
        System.out.println(socket.lastErrorText());
        return;
        }

    socket.Close(10);

    System.out.println("We have Internet connectivity.");
  }
}