(Ruby) POP3 SSH Tunneling (Port Forwarding)

Demonstrates how to connect to a POP3 server through an SSH tunnel. Reads a POP3 mailbox and display the FROM and SUBJECT header fields of each email.

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.

# The mailman object is used for receiving (POP3) 
# and sending (SMTP) email.
mailman = Chilkat::CkMailMan.new()

# 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).
sshHostname = "www.my-ssh-server.com"
sshPort = 22

# Connect to an SSH server and establish the SSH tunnel:
success = mailman.SshOpenTunnel(sshHostname,sshPort)
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# 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 POP3 server, it is
# for authenticating with the SSH server, which is separate.
success = mailman.SshAuthenticatePw("ssh_login","ssh_password")
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# OK, the SSH tunnel is setup.  The mailman may
# be used exactly the same as usual, except all communications
# are now sent through the SSH tunnel.

# The SSH tunnel may be kept open for any number of 
# POP3 connections.  

# Set the POP3 server's hostname
mailman.put_MailHost("mail.my-pop3-server.com")

# Set the POP3 settings for your POP3 server:
mailman.put_PopUsername("pop3_login")
mailman.put_PopPassword("pop3_password")
mailman.put_MailPort(995)
mailman.put_PopSsl(true)

# Connect to the POP3 server through the already-established SSH tunnel:
success = mailman.Pop3BeginSession()
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# A visual inspection of the LastErrorText after
# a successful POP3 connection will confirm the SSH tunneling.
# Note: If the POP3 connection uses SSL/TLS, then the SSL/TLS 
# secure channel will be wrapped within the SSH tunnel.
print mailman.lastErrorText() + "\n";

# How many messages are in the POP3 inbox?
numToDownload = mailman.GetMailboxCount()
if (numToDownload > 5)
    numToDownload = 5
end

if (numToDownload == 0)
    exit
end

# Download a max of 5 messages

for i in 1 .. numToDownload
    # email is a CkEmail
    email = mailman.FetchByMsgnum(i)
    if (mailman.get_LastMethodSuccess() == false)
        print mailman.lastErrorText() + "\n";
        exit
    end

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

end

# Close the connection with the POP3 server, leaving the SSH tunnel open for subsequent POP3 connections.
success = mailman.Pop3EndSession()
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# Try connecting to a different POP3 server through the same aleady setup SSH tunnel:
# Set the POP3 server's hostname
mailman.put_MailHost("mail.my-pop3-server2.com")

# Set the POP3 settings for your POP3 server:
mailman.put_PopUsername("pop3_login2")
mailman.put_PopPassword("pop3_password2")
mailman.put_MailPort(110)
mailman.put_PopSsl(false)

success = mailman.Pop3BeginSession()
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# Review the LastErrorText to see that the connection was made via the SSH tunnel:
print mailman.lastErrorText() + "\n";

success = mailman.Pop3EndSession()
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end

# Close the SSH tunnel.
success = mailman.SshCloseTunnel()
if (success != true)
    print mailman.lastErrorText() + "\n";
    exit
end