Visual FoxPro

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

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.

Visual FoxPro

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

lnSuccess = 0

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

lnSuccess = 0

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 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, 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.

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 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 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 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 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 loTunnel
    RELEASE loFtp
    CANCEL
ENDIF

RELEASE loTunnel
RELEASE loFtp