Java

POP3 over Multiple Hop SSH

Demonstrates how to read POP3 email (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => POP3Server

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.

    CkSsh ssh1 = new CkSsh();

    // Connect directly to the 1st SSH server.
    success = ssh1.Connect("serverssh1.com",22);
    if (success == false) {
        System.out.println(ssh1.lastErrorText());
        return;
        }

    // Authenticate using login/password:
    success = ssh1.AuthenticatePw("ssh1Login","ssh1Password");
    if (success == false) {
        System.out.println(ssh1.lastErrorText());
        return;
        }

    // Connect through the 1st SSH connection to reach a 2nd SSH server.
    // Note: Any number of SSH connections may be simultaneously tunneled through a single
    // existing SSH connection.
    CkSsh ssh2 = new CkSsh();
    success = ssh2.ConnectThroughSsh(ssh1,"serverssh2.com",22);
    if (success == false) {
        System.out.println(ssh2.lastErrorText());
        return;
        }

    // Authenticate with ssh2...
    success = ssh2.AuthenticatePw("ssh2Login","ssh2Password");
    if (success == false) {
        System.out.println(ssh2.lastErrorText());
        return;
        }

    CkMailMan mailman = new CkMailMan();

    // Tell the mailman object to connect to the POP3 server though the ssh2 tunnel (which itself is routed through ssh1).
    // The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => POP3Server
    success = mailman.UseSsh(ssh2);
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Set the POP3 server's hostname
    mailman.put_MailHost("pop.example.com");

    // Set the POP3 login/password.
    mailman.put_PopUsername("myLogin");
    mailman.put_PopPassword("myPassword");

    // Establish the POP3 connection through the ssh2 tunnel.
    success = mailman.Pop3BeginSession();
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Get the number of messages in the mailbox.
    int numMessages = mailman.GetMailboxCount();

    CkEmail email = new CkEmail();
    int i = 1;
    while (i <= numMessages) {
        // Fetch by the message number (not by the UIDL)
        success = mailman.FetchOne(false,0,i,email);
        if (success == false) {
            System.out.println(mailman.lastErrorText());
            return;
            }

        System.out.println(email.ck_from() + ": " + email.subject() + "\n");

        i = i+1;
        }

    // Close the connection with the POP3 server.  (This closes the tunnel through ssh2)
    // The connection with ssh2 is still alive, and may be used for more connections.
    success = mailman.Pop3EndSession();

    // Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
    // The connection with ssh1 is still alive, and may be used for more connections.

    ssh2.Disconnect();

    ssh1.Disconnect();
  }
}