SQL Server

Revert an FTPS Control Channel to Clear Text (CCC)

Demonstrates the Chilkat Ftp2.ClearControlChannel method, which requests that an explicit-FTPS control connection return to clear text after authentication. It takes no arguments. Data connections may remain protected according to the DataProtection property.

Background: The CCC (Clear Command Channel) command exists to solve an FTPS-through-NAT problem: because FTP negotiates data ports in the control channel, a firewall or NAT device must read those commands to open the right ports — which it cannot do when the control channel is encrypted. Reverting the control channel to clear text after login lets the network device help, while the data channel can stay protected. It weakens security on the control channel, so use it only when the network requires it.

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--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the Ftp2.ClearControlChannel method, which requests that an explicit-FTPS control
    --  connection return to clear text after authentication.  It takes no arguments.

    DECLARE @ftp int
    EXEC @hr = sp_OACreate 'Chilkat.Ftp2', @ftp OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OASetProperty @ftp, 'Hostname', 'ftp.example.com'
    EXEC sp_OASetProperty @ftp, 'Username', 'myFtpLogin'

    --  Normally you would not hard-code the password in source.  You should instead obtain it
    --  from an interactive prompt, environment variable, or a secrets vault.
    EXEC sp_OASetProperty @ftp, 'Password', 'myPassword'

    --  Use explicit FTPS (AUTH TLS) on the standard FTP port.
    EXEC sp_OASetProperty @ftp, 'AuthTls', 1

    EXEC sp_OAMethod @ftp, 'Connect', @success OUT
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    --  After a secure login, revert the CONTROL channel to clear text (CCC command).  Data
    --  connections may remain protected according to the DataProtection property.  This is sometimes
    --  required so that NAT/firewall devices can inspect the control channel to open data ports.
    EXEC sp_OAMethod @ftp, 'ClearControlChannel', @success OUT
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    PRINT 'Control channel reverted to clear text.'

    EXEC sp_OAMethod @ftp, 'Disconnect', @success OUT
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    EXEC @hr = sp_OADestroy @ftp


END
GO