(Visual FoxPro) FTP through SSH Tunnel with Dynamic Port Forwarding

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loChilkatGlob
LOCAL lnSuccess
LOCAL loTunnel
LOCAL lcSshHostname
LOCAL lnSshPort
LOCAL loFtp
LOCAL lcLocalFilename
LOCAL lcRemoteFilename
LOCAL lnWaitForThreadExit

* Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
* by calling UnlockBundle.  It requires a Bundle unlock code.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Global')
loChilkatGlob = CreateObject('Chilkat.Global')
lnSuccess = loChilkatGlob.UnlockBundle("Anything for 30-day trial.")
IF (lnSuccess <> 1) THEN
    ? loChilkatGlob.LastErrorText
    RELEASE loChilkatGlob
    CANCEL
ENDIF

* 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 = "sftp.example.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 loChilkatGlob
    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 loChilkatGlob
    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 loChilkatGlob
    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, 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.Ftp2')
loFtp = CreateObject('Chilkat.Ftp2')

* Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
loFtp.SocksHostname = "localhost"
* The SocksPort must equal the port passed to BeginAccepting above.
loFtp.SocksPort = 1080
loFtp.SocksVersion = 5
* The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
loFtp.SocksUsername = "chilkat123"
loFtp.SocksPassword = "password123"

* This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
loFtp.Hostname = "ftp.someFtpServer.com"
loFtp.Username = "myLogin"
loFtp.Password = "myPassword"
loFtp.AuthTls = 1

* Connect and login (via the SSH tunnel) to the FTP server.
lnSuccess = loFtp.Connect()
IF (lnSuccess <> 1) THEN
    ? loFtp.LastErrorText
    RELEASE loChilkatGlob
    RELEASE loTunnel
    RELEASE loFtp
    CANCEL
ENDIF

* Change to the remote directory where the file is located.
* This step is only necessary if the file is not in the root directory
* for the FTP account.
lnSuccess = loFtp.ChangeRemoteDir("junk")
IF (lnSuccess <> 1) THEN
    ? loFtp.LastErrorText
    RELEASE loChilkatGlob
    RELEASE loTunnel
    RELEASE loFtp
    CANCEL
ENDIF

lcLocalFilename = "c:/temp/hamlet.xml"
lcRemoteFilename = "hamlet.xml"

* Download a file.  (the data connection is also automatically established through the 
* SSH tunnel using dynamic port forwarding..)
lnSuccess = loFtp.GetFile(lcRemoteFilename,lcLocalFilename)
IF (lnSuccess <> 1) THEN
    ? loFtp.LastErrorText
    RELEASE loChilkatGlob
    RELEASE loTunnel
    RELEASE loFtp
    CANCEL
ENDIF

* The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
* The background tunnel thread is still running, and may be used for subsequent FTP connections,
* or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
lnSuccess = loFtp.Disconnect()

* When the app is finished with the tunnel, it can cleanup..

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

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

RELEASE loChilkatGlob
RELEASE loTunnel
RELEASE loFtp