SQL Server

Connect an SSH Tunnel to the SSH Server

Demonstrates the Chilkat SshTunnel.Connect method, which establishes the SSH connection that carries the tunnel's traffic. The first argument is the SSH server hostname and the second is the port. It performs the connection, SSH handshake, and host-key negotiation, but does not authenticate the SSH user.

Background: Connecting establishes only the SSH transport — the encrypted channel and host-key exchange. It is the point at which the server's identity becomes known, so it is where a security-conscious client checks HostKeyFingerprint against a trusted value before handing over credentials. Authentication and BeginAccepting follow; nothing is forwarded until they do.

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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
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the SshTunnel.Connect method, which establishes the SSH connection that carries
    --  tunneled traffic.  The 1st argument is the SSH server hostname and the 2nd is the port.  This
    --  performs the connection, SSH handshake, and host-key negotiation, but does not authenticate.

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

    --  The tunnel forwards accepted local connections to this destination through the SSH server.
    EXEC sp_OASetProperty @tunnel, 'DestHostname', 'db.internal.example.com'
    EXEC sp_OASetProperty @tunnel, 'DestPort', 5432

    --  Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
    --  does not authenticate yet.
    DECLARE @sshPort int
    SELECT @sshPort = 22
    EXEC sp_OAMethod @tunnel, 'Connect', @success OUT, 'ssh.example.com', @sshPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  Optionally verify the server's host key before authenticating.

    EXEC sp_OAGetProperty @tunnel, 'HostKeyFingerprint', @sTmp0 OUT
    PRINT 'Host key fingerprint: ' + @sTmp0

    --  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.
    DECLARE @password nvarchar(4000)
    SELECT @password = 'mySshPassword'

    EXEC sp_OAMethod @tunnel, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  After authenticating, call BeginAccepting to start listening for local connections to forward.

    DECLARE @waitForThreadExit int
    SELECT @waitForThreadExit = 1
    EXEC sp_OAMethod @tunnel, 'CloseTunnel', @success OUT, @waitForThreadExit
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    EXEC @hr = sp_OADestroy @tunnel


END
GO