DataFlex

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.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoTunnel
    String sSshHostname
    Integer iSshPort
    Handle hoFtp
    String sLocalFilename
    String sRemoteFilename
    Boolean iWaitForThreadExit
    String sTemp1

    Move False To iSuccess

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

    Move False To iSuccess

    Get Create (RefClass(cComChilkatSshTunnel)) To hoTunnel
    If (Not(IsComObjectCreated(hoTunnel))) Begin
        Send CreateComObject of hoTunnel
    End

    Move "sftp.example.com" To sSshHostname
    Move 22 To iSshPort

    // Connect to an SSH server and establish the SSH tunnel:
    Get ComConnect Of hoTunnel sSshHostname iSshPort To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    Get ComAuthenticatePw Of hoTunnel "mySshLogin" "mySshPassword" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
    // with dynamic port forwarding:
    Set ComDynamicPortForwarding Of hoTunnel To 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.

    Set ComInboundSocksUsername Of hoTunnel To "chilkat123"
    Set ComInboundSocksPassword Of hoTunnel To "password123"

    // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
    // Listen on port 1080.
    Get ComBeginAccepting Of hoTunnel 1080 To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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.

    Get Create (RefClass(cComChilkatFtp2)) To hoFtp
    If (Not(IsComObjectCreated(hoFtp))) Begin
        Send CreateComObject of hoFtp
    End

    // Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    Set ComSocksHostname Of hoFtp To "localhost"
    // The SocksPort must equal the port passed to BeginAccepting above.
    Set ComSocksPort Of hoFtp To 1080
    Set ComSocksVersion Of hoFtp To 5
    // The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
    Set ComSocksUsername Of hoFtp To "chilkat123"
    Set ComSocksPassword Of hoFtp To "password123"

    // This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
    Set ComHostname Of hoFtp To "ftp.someFtpServer.com"
    Set ComUsername Of hoFtp To "myLogin"
    Set ComPassword Of hoFtp To "myPassword"
    Set ComAuthTls Of hoFtp To True

    // Connect and login (via the SSH tunnel) to the FTP server.
    Get ComConnect Of hoFtp To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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.
    Get ComChangeRemoteDir Of hoFtp "junk" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Move "c:/temp/hamlet.xml" To sLocalFilename
    Move "hamlet.xml" To sRemoteFilename

    // Download a file.  (the data connection is also automatically established through the 
    // SSH tunnel using dynamic port forwarding..)
    Get ComGetFile Of hoFtp sRemoteFilename sLocalFilename To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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.
    Get ComDisconnect Of hoFtp To iSuccess

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

    // Stop the background listen/accept thread:
    Move True To iWaitForThreadExit
    Get ComStopAccepting Of hoTunnel iWaitForThreadExit To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Close the SSH tunnel (would also kick any remaining connected clients).
    Get ComCloseTunnel Of hoTunnel iWaitForThreadExit To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End



End_Procedure