Java

SSH Tunnel Inside another SSH Tunnel

See more SSH Tunnel Examples

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel. 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;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkSshTunnel tunnel = new CkSshTunnel();

    String sshHostname = "www.ssh-serverA.com";
    int sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.Connect(sshHostname,sshPort);
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    success = tunnel.AuthenticatePw("mySshLogin","mySshPassword");
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
    // with dynamic port forwarding:
    tunnel.put_DynamicPortForwarding(true);

    // We may optionally require that connecting clients authenticate with our SOCKS proxy server.
    // To do this, set an inbound username/password.  Any connecting clients would be required to 
    // use SOCKS5 with the correct username/password.
    // If no inbound username/password is set, then our SOCKS proxy server will accept both
    // SOCKS4 and SOCKS5 unauthenticated connections.

    tunnel.put_InboundSocksUsername("chilkat123");
    tunnel.put_InboundSocksPassword("password123");

    // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
    // Listen on port 1080.
    success = tunnel.BeginAccepting(1080);
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // Now that a background thread is running a SOCKS proxy server that forwards connections
    // through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
    // such as HTTP, POP3, SMTP, IMAP, FTP, Socket, etc.  The protocol may use SSL/TLS because the SSL/TLS
    // will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
    // connections may be routed through the SSH tunnel.

    CkSocket tunnelB = new CkSocket();

    // Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    tunnelB.put_SocksHostname("localhost");
    tunnelB.put_SocksPort(1080);
    tunnelB.put_SocksVersion(5);
    tunnelB.put_SocksUsername("chilkat123");
    tunnelB.put_SocksPassword("password123");

    // Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
    // but it is actually a dynamic port-forwarded SSH tunnel).
    success = tunnelB.SshOpenTunnel("www.ssh-serverB.com",22);
    if (success == false) {
        System.out.println(tunnelB.lastErrorText());
        return;
        }

    // Authenticate with ssh-serverB.com
    success = tunnelB.SshAuthenticatePw("uname","pwd");
    if (success == false) {
        System.out.println(tunnelB.lastErrorText());
        return;
        }

    // OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket API may
    // be used exactly the same as usual, except all communications
    // are sent through the channel in the SSH tunnel.
    // Any number of channels may be created from the same SSH tunnel.
    // Multiple channels may coexist at the same time.

    // Connect to an NIST time server and read the current date/time
    CkSocket channel = new CkSocket();
    int maxWaitMs = 4000;
    boolean useTls = false;
    success = tunnelB.SshNewChannel("time-c.nist.gov",37,useTls,maxWaitMs,channel);
    if (success == false) {
        System.out.println(tunnelB.lastErrorText());
        return;
        }

    // The time server will send a big-endian 32-bit integer representing
    // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
    // The ReceiveInt32 method will receive a 4-byte integer, but returns
    // true or false to indicate success.  If successful, the integer
    // is obtained via the ReceivedInt property.
    boolean bigEndian = true;
    success = channel.ReceiveInt32(bigEndian);
    if (success == false) {
        System.out.println(channel.lastErrorText());
        return;
        }

    CkDateTime dt = new CkDateTime();
    dt.SetFromNtpTime(channel.get_ReceivedInt());

    // Show the current local date/time
    boolean bLocalTime = true;
    System.out.println("Current local date/time: " + dt.getAsRfc822(bLocalTime));

    // Close the SSH channel.
    success = channel.Close(maxWaitMs);
    if (success == false) {
        System.out.println(channel.lastErrorText());
        return;
        }

    // Stop the background listen/accept thread:
    boolean waitForThreadExit = true;
    success = tunnel.StopAccepting(waitForThreadExit);
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // Close the SSH tunnel (would also kick any remaining connected clients).
    success = tunnel.CloseTunnel(waitForThreadExit);
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }
  }
}