Xojo Plugin

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.

Xojo Plugin

Dim success As Boolean
success = False

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

success = False

Dim tunnel As New Chilkat.SshTunnel

Dim sshHostname As String
sshHostname = "sftp.example.com"
Dim sshPort As Int32
sshPort = 22

// Connect to an SSH server and establish the SSH tunnel:
success = tunnel.Connect(sshHostname,sshPort)
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
End If

// Authenticate with the SSH server via a login/password
// or with a public key.  
// This example demonstrates SSH password authentication.
success = tunnel.AuthenticatePw("mySshLogin","mySshPassword")
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
End If

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

// 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.

tunnel.InboundSocksUsername = "chilkat123"
tunnel.InboundSocksPassword = "password123"

// Start the listen/accept thread to begin accepting SOCKS proxy client connections.
// Listen on port 1080.
success = tunnel.BeginAccepting(1080)
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    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.

Dim ftp As New Chilkat.Ftp2

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

// Connect and login (via the SSH tunnel) to the FTP server.
success = ftp.Connect()
If (success <> True) Then
    System.DebugLog(ftp.LastErrorText)
    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.
success = ftp.ChangeRemoteDir("junk")
If (success <> True) Then
    System.DebugLog(ftp.LastErrorText)
    Return
End If

Dim localFilename As String
localFilename = "c:/temp/hamlet.xml"
Dim remoteFilename As String
remoteFilename = "hamlet.xml"

// Download a file.  (the data connection is also automatically established through the 
// SSH tunnel using dynamic port forwarding..)
success = ftp.GetFile(remoteFilename,localFilename)
If (success <> True) Then
    System.DebugLog(ftp.LastErrorText)
    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.
success = ftp.Disconnect()

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

// Stop the background listen/accept thread:
Dim waitForThreadExit As Boolean
waitForThreadExit = True
success = tunnel.StopAccepting(waitForThreadExit)
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
End If

// Close the SSH tunnel (would also kick any remaining connected clients).
success = tunnel.CloseTunnel(waitForThreadExit)
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
End If