SQL Server

Get an SSH Tunnel's Current State (Diagnostics)

Demonstrates the Chilkat SshTunnel.GetCurrentState method, which returns an XML snapshot describing the tunnel manager, SSH channels, and current tunnel clients. It takes no arguments and is intended for diagnostics and monitoring.

Background: Because the tunnel forwards traffic on a background thread, there is no natural place in your code to observe what it is doing at a given moment. GetCurrentState provides that visibility — byte counts, active channels, and connected clients — as structured XML suited to logging or a monitoring dashboard. It is a read-only snapshot and does not affect the tunnel.

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-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the SshTunnel.GetCurrentState method, which returns an XML snapshot describing the
    --  tunnel manager, SSH channels, and current tunnel clients.  It takes no arguments and is
    --  intended for diagnostics and monitoring.

    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

    --  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

    --  Begin accepting so there is live tunnel state to inspect.
    DECLARE @listenPort int
    SELECT @listenPort = 1080
    EXEC sp_OAMethod @tunnel, 'BeginAccepting', @success OUT, @listenPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  Get a diagnostic snapshot of the tunnel's current state as XML.
    DECLARE @stateXml nvarchar(4000)
    EXEC sp_OAMethod @tunnel, 'GetCurrentState', @stateXml OUT
    EXEC sp_OAGetProperty @tunnel, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    PRINT @stateXml

    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