PowerBuilder

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.

PowerBuilder

integer li_rc
long li_Success
oleobject loo_Tunnel
string ls_SshHostname
long li_SshPort
oleobject loo_Ftp
string ls_LocalFilename
string ls_RemoteFilename
long li_WaitForThreadExit

li_Success = 0

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

li_Success = 0

loo_Tunnel = create oleobject
li_rc = loo_Tunnel.ConnectToNewObject("Chilkat.SshTunnel")
if li_rc < 0 then
    destroy loo_Tunnel
    MessageBox("Error","Connecting to COM object failed")
    return
end if

ls_SshHostname = "sftp.example.com"
li_SshPort = 22

//  Connect to an SSH server and establish the SSH tunnel:
li_Success = loo_Tunnel.Connect(ls_SshHostname,li_SshPort)
if li_Success <> 1 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

//  Authenticate with the SSH server via a login/password
//  or with a public key.  
//  This example demonstrates SSH password authentication.
li_Success = loo_Tunnel.AuthenticatePw("mySshLogin","mySshPassword")
if li_Success <> 1 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

//  Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
//  with dynamic port forwarding:
loo_Tunnel.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.

loo_Tunnel.InboundSocksUsername = "chilkat123"
loo_Tunnel.InboundSocksPassword = "password123"

//  Start the listen/accept thread to begin accepting SOCKS proxy client connections.
//  Listen on port 1080.
li_Success = loo_Tunnel.BeginAccepting(1080)
if li_Success <> 1 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

//  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.

loo_Ftp = create oleobject
li_rc = loo_Ftp.ConnectToNewObject("Chilkat.Ftp2")

//  Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
loo_Ftp.SocksHostname = "localhost"
//  The SocksPort must equal the port passed to BeginAccepting above.
loo_Ftp.SocksPort = 1080
loo_Ftp.SocksVersion = 5
//  The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
loo_Ftp.SocksUsername = "chilkat123"
loo_Ftp.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.
loo_Ftp.Hostname = "ftp.someFtpServer.com"
loo_Ftp.Username = "myLogin"
loo_Ftp.Password = "myPassword"
loo_Ftp.AuthTls = 1

//  Connect and login (via the SSH tunnel) to the FTP server.
li_Success = loo_Ftp.Connect()
if li_Success <> 1 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Tunnel
    destroy loo_Ftp
    return
end if

//  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.
li_Success = loo_Ftp.ChangeRemoteDir("junk")
if li_Success <> 1 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Tunnel
    destroy loo_Ftp
    return
end if

ls_LocalFilename = "c:/temp/hamlet.xml"
ls_RemoteFilename = "hamlet.xml"

//  Download a file.  (the data connection is also automatically established through the 
//  SSH tunnel using dynamic port forwarding..)
li_Success = loo_Ftp.GetFile(ls_RemoteFilename,ls_LocalFilename)
if li_Success <> 1 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Tunnel
    destroy loo_Ftp
    return
end if

//  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.
li_Success = loo_Ftp.Disconnect()

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

//  Stop the background listen/accept thread:
li_WaitForThreadExit = 1
li_Success = loo_Tunnel.StopAccepting(li_WaitForThreadExit)
if li_Success <> 1 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Ftp
    return
end if

//  Close the SSH tunnel (would also kick any remaining connected clients).
li_Success = loo_Tunnel.CloseTunnel(li_WaitForThreadExit)
if li_Success <> 1 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Ftp
    return
end if



destroy loo_Tunnel
destroy loo_Ftp