(Ruby) 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

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

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

ssh1 = Chilkat::CkSsh.new()

# Connect directly to the 1st SSH server.
success = ssh1.Connect("serverssh1.com",22)
if (success != true)
    print ssh1.lastErrorText() + "\n";
    exit
end

# Authenticate using login/password:
success = ssh1.AuthenticatePw("ssh1Login","ssh1Password")
if (success != true)
    print ssh1.lastErrorText() + "\n";
    exit
end

# 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.
ssh2 = Chilkat::CkSsh.new()
success = ssh2.ConnectThroughSsh(ssh1,"serverssh2.com",22)
if (success != true)
    print ssh2.lastErrorText() + "\n";
    exit
end

# Authenticate with ssh2...
success = ssh2.AuthenticatePw("ssh2Login","ssh2Password")
if (success != true)
    print ssh2.lastErrorText() + "\n";
    exit
end

mailman = Chilkat::CkMailMan.new()

# 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)
    print mailman.lastErrorText() + "\n";
    exit
end

# Set the POP3 server's hostname
mailman.put_MailHost("pop.someMailServer.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 != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# Get the number of messages in the mailbox.
numMessages = mailman.GetMailboxCount()

i = 1

while i <= numMessages

    # email is a CkEmail
    email = mailman.FetchByMsgnum(i)
    if (mailman.get_LastMethodSuccess() != true)
        print mailman.lastErrorText() + "\n";
        exit
    end

    print email.ck_from() + ": " + email.subject() + "\n" + "\n";

    i = i + 1
end

# 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()