Java Requires Chilkat v11.0.0+

TCP Socket through SSH Tunnel (Port Forwarding)

See more Socket/SSL/TLS Examples

Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time.

Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.

Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.DateTime;
import com.chilkatsoft.chilkat2.Socket;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        Socket tunnel = new Socket();

        String sshHostname = "sftp.example.com";
        int sshPort = 22;

        // Connect to an SSH server and establish the SSH tunnel:
        try {
            tunnel.sshOpenTunnel(sshHostname, sshPort);

            // Authenticate with the SSH server via a login/password
            // or with a public key.
            // This example demonstrates SSH password authentication.
            tunnel.sshAuthenticatePw("mySshLogin", "mySshPassword");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // OK, the SSH 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
        int maxWaitMs = 4000;
        boolean useTls = false;
        Socket channel = new Socket();
        try {
            tunnel.sshNewChannel("time-c.nist.gov", 37, useTls, maxWaitMs, channel);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            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;
        try {
            channel.receiveInt32(bigEndian);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        DateTime dt = new DateTime();
        dt.setFromNtpTime(channel.getReceivedInt());

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

        // Close the SSH channel.
        try {
            channel.closeConnection(maxWaitMs);

            // It is possible to create a new channel from the existing SSH tunnel for the next connection:
            // Any number of channels may be created from the same SSH tunnel.
            // Multiple channels may coexist at the same time.
            tunnel.sshNewChannel("time-a.nist.gov", 37, useTls, maxWaitMs, channel);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Review the LastErrorText to see that the connection was made via the SSH tunnel:
        System.out.println(tunnel.getLastErrorText());

        // Close the connection to time-a.nist.gov.  This is actually closing our channel
        // within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
        try {
            channel.closeConnection(maxWaitMs);

            // Finally, close the SSH tunnel.
            tunnel.sshCloseTunnel();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("TCP SSH tunneling example completed.");
    }
}