(.NET Core C#) 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

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

Chilkat.Ssh ssh1 = new Chilkat.Ssh();

// Connect directly to the 1st SSH server.
bool success = ssh1.Connect("serverssh1.com",22);
if (success != true) {
    Debug.WriteLine(ssh1.LastErrorText);
    return;
}

// Authenticate using login/password:
success = ssh1.AuthenticatePw("ssh1Login","ssh1Password");
if (success != true) {
    Debug.WriteLine(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.
Chilkat.Ssh ssh2 = new Chilkat.Ssh();
success = ssh2.ConnectThroughSsh(ssh1,"serverssh2.com",22);
if (success != true) {
    Debug.WriteLine(ssh2.LastErrorText);
    return;
}

// Authenticate with ssh2...
success = ssh2.AuthenticatePw("ssh2Login","ssh2Password");
if (success != true) {
    Debug.WriteLine(ssh2.LastErrorText);
    return;
}

Chilkat.MailMan mailman = new Chilkat.MailMan();

// 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 != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Set the POP3 server's hostname
mailman.MailHost = "pop.someMailServer.com";

// Set the POP3 login/password.
mailman.PopUsername = "myLogin";
mailman.PopPassword = "myPassword";

// Establish the POP3 connection through the ssh2 tunnel.
success = mailman.Pop3BeginSession();
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

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

int i = 1;

Chilkat.Email email = null;
while (i <= numMessages) {

    email = mailman.FetchByMsgnum(i);
    if (mailman.LastMethodSuccess != true) {
        Debug.WriteLine(mailman.LastErrorText);
        return;
    }

    Debug.WriteLine(email.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();