(Mono C#) SMTP over Multiple Hop SSH

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

Application => ServerSSH1 => ServerSSH2 => SmtpServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

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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 SMTP server though the ssh2 tunnel (which itself is routed through ssh1).
// The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => SMTPServer
success = mailman.UseSsh(ssh2);
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Set the SMTP server.
mailman.SmtpHost = "smtp.someserver.com";

// Set the SMTP login/password (if required)
mailman.SmtpUsername = "myUsername";
mailman.SmtpPassword = "myPassword";

// Create a new email object
Chilkat.Email email = new Chilkat.Email();

email.Subject = "This is a test";
email.Body = "This is a test";
email.From = "Chilkat Support <support@chilkatsoft.com>";
success = email.AddTo("Chilkat Admin","admin@chilkatsoft.com");

success = mailman.SendEmail(email);
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// Close the connection with the server.  This closes the tunnel through ssh2.
success = mailman.CloseSmtpConnection();
if (success != true) {
    Debug.WriteLine("Connection to SMTP server not closed cleanly.");
}

Debug.WriteLine("Mail Sent!");

// 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();