Java

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Ftp2;
import com.chilkatsoft.chilkat2.SshTunnel;

public class ChilkatExample {

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

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

        success = false;

        SshTunnel tunnel = new SshTunnel();

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

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

            // Authenticate with the SSH server via a login/password
            // or with a public key.
            // This example demonstrates SSH password authentication.
            tunnel.authenticatePw("mySshLogin", "mySshPassword");

            // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
            // with dynamic port forwarding:
            tunnel.setDynamicPortForwarding(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.setInboundSocksUsername("chilkat123");
            tunnel.setInboundSocksPassword("password123");

            // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
            // Listen on port 1080.
            tunnel.beginAccepting(1080);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            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, 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.

        Ftp2 ftp = new Ftp2();

        // Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
        ftp.setSocksHostname("localhost");
        // The SocksPort must equal the port passed to BeginAccepting above.
        ftp.setSocksPort(1080);
        ftp.setSocksVersion(5);
        // The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
        ftp.setSocksUsername("chilkat123");
        ftp.setSocksPassword("password123");

        // This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
        ftp.setHostname("ftp.someFtpServer.com");
        ftp.setUsername("myLogin");
        ftp.setPassword("myPassword");
        ftp.setAuthTls(true);

        // Connect and login (via the SSH tunnel) to the FTP server.
        try {
            ftp.connect();

            // Change to the remote directory where the file is located.
            // This step is only necessary if the file is not in the root directory
            // for the FTP account.
            ftp.changeRemoteDir("junk");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        String localFilename = "c:/temp/hamlet.xml";
        String remoteFilename = "hamlet.xml";

        // Download a file.  (the data connection is also automatically established through the
        // SSH tunnel using dynamic port forwarding..)
        try {
            ftp.getFile(remoteFilename, localFilename);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
        // The background tunnel thread is still running, and may be used for subsequent FTP connections,
        // or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
        ftp.disconnect();

        // When the app is finished with the tunnel, it can cleanup..

        // Stop the background listen/accept thread:
        boolean waitForThreadExit = true;
        try {
            tunnel.stopAccepting(waitForThreadExit);

            // Close the SSH tunnel (would also kick any remaining connected clients).
            tunnel.closeTunnel(waitForThreadExit);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }
    }
}