(Java) IMAP SSH Tunneling (Port Forwarding)

Demonstrates how to setup and use an SSH tunnel for IMAP.

Note: This example requires Chilkat v11.0.0 or greater.

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

    CkImap imap = new CkImap();

    // The SSH hostname may be a hostname or an 
    // IP address, such as "192.168.1.108".
    // The port is typically 22 (the standard port for SSH).
    String sshHostname = "www.mysshserver.com";
    int sshPort = 22;

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

    // Authenticate with the SSH server via a login/password
    // or with a public key.
    // This example demonstrates SSH password authentication.
    // Note: This is not authenticating with the IMAP server, it is
    // for authenticating with the SSH server, which is separate.
    success = imap.SshAuthenticatePw("mySshLogin","mySshPassword");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // OK, the SSH tunnel is setup.  The IMAP component may
    // be used exactly the same as usual, except all communications
    // are sent through the SSH tunnel.

    // Connect to an IMAP server via the SSH tunnel.
    // Because the SSH tunnel has been previously setup,
    // this does not establish a direct connection with the IMAP
    // server.  It directs the SSH server to establish the connection.

    // In this example, the IMAP server requires SSL/TLS.  The TLS connection
    // will be enclosed within the SSH tunnel.
    imap.put_Ssl(true);
    imap.put_Port(993);
    success = imap.Connect("imap.my-imap-server.com");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Authenticate with the IMAP server via the SSH tunnel.
    success = imap.Login("myLogin","myPassword");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // How many messages in Inbox?
    int msgCount = imap.get_NumMessages();
    if (msgCount == 0) {
        System.out.println("No messages found.");
        return;
        }

    int upperBound = 10;
    if (msgCount < upperBound) {
        upperBound = msgCount;
        }

    // Download up to the 1st 10 messages.
    CkEmail email = new CkEmail();
    int i;
    boolean bUid = false;
    for (i = 1; i <= upperBound; i++) {

        success = imap.FetchEmail(false,i,bUid,email);
        if (success == false) {
            System.out.println(imap.lastErrorText());
            return;
            }

        System.out.println(email.ck_from());
        System.out.println(email.subject());
        System.out.println("----");
        }

    // Disconnect from the IMAP server.
    // The SSH tunnel remains open.
    success = imap.Disconnect();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // It is possible to re-use the existing SSH tunnel for the next connection:
    success = imap.Connect("imap.my-imap-server2.com");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

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

    success = imap.Disconnect();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Finally, close the SSH tunnel.
    success = imap.SshCloseTunnel();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

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