(Visual FoxPro) SSH Tunnel Inside another SSH Tunnel

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel.

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LOCAL loTunnel
LOCAL lcSshHostname
LOCAL lnSshPort
LOCAL lnSuccess
LOCAL loTunnelB
LOCAL loChannel
LOCAL lnMaxWaitMs
LOCAL lnUseTls
LOCAL lnBigEndian
LOCAL loDt
LOCAL lnBLocalTime
LOCAL lnWaitForThreadExit

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

* This example requires Chilkat version 9.5.0.50 or greater.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.SshTunnel')
loTunnel = CreateObject('Chilkat.SshTunnel')

lcSshHostname = "www.ssh-serverA.com"
lnSshPort = 22

* Connect to an SSH server and establish the SSH tunnel:
lnSuccess = loTunnel.Connect(lcSshHostname,lnSshPort)
IF (lnSuccess <> 1) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* Authenticate with the SSH server via a login/password
* or with a public key.  
* This example demonstrates SSH password authentication.
lnSuccess = loTunnel.AuthenticatePw("mySshLogin","mySshPassword")
IF (lnSuccess <> 1) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
* with dynamic port forwarding:
loTunnel.DynamicPortForwarding = 1

* We may optionally require that connecting clients authenticate with our SOCKS proxy server.
* To do this, set an inbound username/password.  Any connecting clients would be required to 
* use SOCKS5 with the correct username/password.
* If no inbound username/password is set, then our SOCKS proxy server will accept both
* SOCKS4 and SOCKS5 unauthenticated connections.

loTunnel.InboundSocksUsername = "chilkat123"
loTunnel.InboundSocksPassword = "password123"

* Start the listen/accept thread to begin accepting SOCKS proxy client connections.
* Listen on port 1080.
lnSuccess = loTunnel.BeginAccepting(1080)
IF (lnSuccess <> 1) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* Now that a background thread is running a SOCKS proxy server that forwards connections
* through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
* such as HTTP, POP3, SMTP, IMAP, FTP, Socket, etc.  The protocol may use SSL/TLS because the SSL/TLS
* will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
* connections may be routed through the SSH tunnel.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Socket')
loTunnelB = CreateObject('Chilkat.Socket')

* Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
loTunnelB.SocksHostname = "localhost"
loTunnelB.SocksPort = 1080
loTunnelB.SocksVersion = 5
loTunnelB.SocksUsername = "chilkat123"
loTunnelB.SocksPassword = "password123"

* Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
* but it is actually a dynamic port-forwarded SSH tunnel).
lnSuccess = loTunnelB.SshOpenTunnel("www.ssh-serverB.com",22)
IF (lnSuccess <> 1) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* Authenticate with ssh-serverB.com
lnSuccess = loTunnelB.SshAuthenticatePw("uname","pwd")
IF (lnSuccess <> 1) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
* Once the channel is obtained, the Socket API may
* be used exactly the same as usual, except all communications
* are sent through the channel in the SSH tunnel.
* Any number of channels may be created from the same SSH tunnel.
* Multiple channels may coexist at the same time.

* Connect to an NIST time server and read the current date/time

lnMaxWaitMs = 4000
lnUseTls = 0
loChannel = loTunnelB.SshOpenChannel("time-c.nist.gov",37,lnUseTls,lnMaxWaitMs)
IF (loTunnelB.LastMethodSuccess = 0) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* The time server will send a big-endian 32-bit integer representing
* the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
* The ReceiveInt32 method will receive a 4-byte integer, but returns
* 1 or 0 to indicate success.  If successful, the integer
* is obtained via the ReceivedInt property.
lnBigEndian = 1
lnSuccess = loChannel.ReceiveInt32(lnBigEndian)
IF (lnSuccess <> 1) THEN
    ? loChannel.LastErrorText
    RELEASE loChannel
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.CkDateTime')
loDt = CreateObject('Chilkat.CkDateTime')
loDt.SetFromNtpTime(loChannel.ReceivedInt)

* Show the current local date/time
lnBLocalTime = 1
? "Current local date/time: " + loDt.GetAsRfc822(lnBLocalTime)

* Close the SSH channel.
lnSuccess = loChannel.Close(lnMaxWaitMs)
IF (lnSuccess <> 1) THEN
    ? loChannel.LastErrorText
    RELEASE loChannel
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loDt
    CANCEL
ENDIF

RELEASE loChannel

* Stop the background listen/accept thread:
lnWaitForThreadExit = 1
lnSuccess = loTunnel.StopAccepting(lnWaitForThreadExit)
IF (lnSuccess <> 1) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loDt
    CANCEL
ENDIF

* Close the SSH tunnel (would also kick any remaining connected clients).
lnSuccess = loTunnel.CloseTunnel(lnWaitForThreadExit)
IF (lnSuccess <> 1) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loDt
    CANCEL
ENDIF

RELEASE loTunnel
RELEASE loTunnelB
RELEASE loDt