SQL Server

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.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    SELECT @success = 0

    DECLARE @tunnel int
    EXEC @hr = sp_OACreate 'Chilkat.SshTunnel', @tunnel OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @sshHostname nvarchar(4000)
    SELECT @sshHostname = 'sftp.example.com'
    DECLARE @sshPort int
    SELECT @sshPort = 22

    -- Connect to an SSH server and establish the SSH tunnel:
    EXEC sp_OAMethod @tunnel, 'Connect', @success OUT, @sshHostname, @sshPort
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    -- Authenticate with the SSH server via a login/password
    -- or with a public key.  
    -- This example demonstrates SSH password authentication.
    EXEC sp_OAMethod @tunnel, 'AuthenticatePw', @success OUT, 'mySshLogin', 'mySshPassword'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    -- Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
    -- with dynamic port forwarding:
    EXEC sp_OASetProperty @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.

    EXEC sp_OASetProperty @tunnel, 'InboundSocksUsername', 'chilkat123'
    EXEC sp_OASetProperty @tunnel, 'InboundSocksPassword', 'password123'

    -- Start the listen/accept thread to begin accepting SOCKS proxy client connections.
    -- Listen on port 1080.
    EXEC sp_OAMethod @tunnel, 'BeginAccepting', @success OUT, 1080
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        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.

    DECLARE @ftp int
    EXEC @hr = sp_OACreate 'Chilkat.Ftp2', @ftp OUT

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

    -- Connect and login (via the SSH tunnel) to the FTP server.
    EXEC sp_OAMethod @ftp, 'Connect', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        EXEC @hr = sp_OADestroy @ftp
        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.
    EXEC sp_OAMethod @ftp, 'ChangeRemoteDir', @success OUT, 'junk'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    DECLARE @localFilename nvarchar(4000)
    SELECT @localFilename = 'c:/temp/hamlet.xml'
    DECLARE @remoteFilename nvarchar(4000)
    SELECT @remoteFilename = 'hamlet.xml'

    -- Download a file.  (the data connection is also automatically established through the 
    -- SSH tunnel using dynamic port forwarding..)
    EXEC sp_OAMethod @ftp, 'GetFile', @success OUT, @remoteFilename, @localFilename
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        EXEC @hr = sp_OADestroy @ftp
        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.
    EXEC sp_OAMethod @ftp, 'Disconnect', @success OUT

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

    -- Stop the background listen/accept thread:
    DECLARE @waitForThreadExit int
    SELECT @waitForThreadExit = 1
    EXEC sp_OAMethod @tunnel, 'StopAccepting', @success OUT, @waitForThreadExit
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    -- Close the SSH tunnel (would also kick any remaining connected clients).
    EXEC sp_OAMethod @tunnel, 'CloseTunnel', @success OUT, @waitForThreadExit
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    EXEC @hr = sp_OADestroy @tunnel
    EXEC @hr = sp_OADestroy @ftp


END
GO