Tcl

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

Tcl

load ./chilkat.dll

set success 0

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

set ssh1 [new_CkSsh]

# Connect directly to the 1st SSH server.
set success [CkSsh_Connect $ssh1 "serverssh1.com" 22]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh1]
    delete_CkSsh $ssh1
    exit
}

# Authenticate using login/password:
set success [CkSsh_AuthenticatePw $ssh1 "ssh1Login" "ssh1Password"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh1]
    delete_CkSsh $ssh1
    exit
}

# 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.
set ssh2 [new_CkSsh]

set success [CkSsh_ConnectThroughSsh $ssh2 $ssh1 "serverssh2.com" 22]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

# Authenticate with ssh2...
set success [CkSsh_AuthenticatePw $ssh2 "ssh2Login" "ssh2Password"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

set 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
set success [CkMailMan_UseSsh $mailman $ssh2]
if {$success == 0} then {
    puts [CkMailMan_lastErrorText $mailman]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkMailMan $mailman
    exit
}

# Set the POP3 server's hostname
CkMailMan_put_MailHost $mailman "pop.example.com"

# Set the POP3 login/password.
CkMailMan_put_PopUsername $mailman "myLogin"
CkMailMan_put_PopPassword $mailman "myPassword"

# Establish the POP3 connection through the ssh2 tunnel.
set success [CkMailMan_Pop3BeginSession $mailman]
if {$success == 0} then {
    puts [CkMailMan_lastErrorText $mailman]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkMailMan $mailman
    exit
}

# Get the number of messages in the mailbox.
set numMessages [CkMailMan_GetMailboxCount $mailman]

set email [new_CkEmail]

set i 1
while {$i <= $numMessages} {
    # Fetch by the message number (not by the UIDL)
    set success [CkMailMan_FetchOne $mailman 0 0 $i $email]
    if {$success == 0} then {
        puts [CkMailMan_lastErrorText $mailman]
        delete_CkSsh $ssh1
        delete_CkSsh $ssh2
        delete_CkMailMan $mailman
        delete_CkEmail $email
        exit
    }

    puts [CkEmail_from $email]: [CkEmail_subject $email]\n

    set i [expr $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.
set success [CkMailMan_Pop3EndSession $mailman]

# 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.

CkSsh_Disconnect $ssh2

CkSsh_Disconnect $ssh1

delete_CkSsh $ssh1
delete_CkSsh $ssh2
delete_CkMailMan $mailman
delete_CkEmail $email