SSH Tunnel (Port Forwarding via direct-tcpip Channel)

See more SSH Examples

Demonstrates creating an SSH tunnel to a remote host:port using a direct-tcpip channel. Data written to the channel is forwarded by the SSH server to the target, and data read back is whatever the target sent. This example tunnels a simple HTTP GET request to a web 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 @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    --  Demonstrates creating an SSH tunnel to a remote host:port using a direct-tcpip channel.
    --  Data written to the channel is forwarded by the SSH server to the target host:port, and data
    --  read from the channel is whatever the target sent back.

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

    DECLARE @hostname nvarchar(4000)
    SELECT @hostname = 'ssh.example.com'
    DECLARE @port int
    SELECT @port = 22
    EXEC sp_OAMethod @ssh, 'Connect', @success OUT, @hostname, @port
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        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 @ssh, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Ask the SSH server to connect onward to this host:port.  The target is resolved by the SSH
    --  server, not by this computer, so it must be reachable from the server's network.  The target
    --  need not be a web server -- it can be any TCP service.
    DECLARE @targetHost nvarchar(4000)
    SELECT @targetHost = 'www.chilkatsoft.com'
    DECLARE @targetPort int
    SELECT @targetPort = 80
    DECLARE @channelNum int
    EXEC sp_OAMethod @ssh, 'OpenDirectTcpIpChannel', @channelNum OUT, @targetHost, @targetPort
    IF @channelNum < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Send a simple HTTP GET request through the tunnel.
    DECLARE @httpReq nvarchar(4000)
    SELECT @httpReq = 'GET /xyz123.html HTTP/1.1' + CHAR(13) + CHAR(10) + 'Host: www.chilkatsoft.com' + CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10)
    EXEC sp_OAMethod @ssh, 'ChannelSendString', @success OUT, @channelNum, @httpReq, 'utf-8'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
    --  which means no limit -- without it, this call waits forever if the received data never
    --  contains a match.
    EXEC sp_OASetProperty @ssh, 'ReadTimeoutMs', 15000

    --  An HTTP response header ends with a blank line, so receive until a double CRLF is seen.
    --  The method may read beyond the match, but it stops waiting as soon as the match appears.
    DECLARE @caseSensitive int
    SELECT @caseSensitive = 0
    DECLARE @matchStr nvarchar(4000)
    SELECT @matchStr = CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10)
    EXEC sp_OAMethod @ssh, 'ChannelReceiveUntilMatch', @success OUT, @channelNum, @matchStr, 'utf-8', @caseSensitive
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  GetReceivedTextS removes everything through and including the match, which is exactly the
    --  response header.
    DECLARE @responseHeader nvarchar(4000)
    EXEC sp_OAMethod @ssh, 'GetReceivedTextS', @responseHeader OUT, @channelNum, @matchStr, 'utf-8'
    EXEC sp_OAGetProperty @ssh, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    PRINT '---- HTTP Response Header ----'

    PRINT @responseHeader

    --  The body may already have arrived along with the header.  Poll briefly for anything more.
    --  A -2 return simply means nothing further arrived, which is not an error here.
    DECLARE @pollTimeoutMs int
    SELECT @pollTimeoutMs = 200
    DECLARE @numBytesRead int
    EXEC sp_OAMethod @ssh, 'ChannelPoll', @numBytesRead OUT, @channelNum, @pollTimeoutMs
    IF @numBytesRead = -1
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    DECLARE @htmlBody nvarchar(4000)
    EXEC sp_OAMethod @ssh, 'GetReceivedText', @htmlBody OUT, @channelNum, 'utf-8'
    EXEC sp_OAGetProperty @ssh, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    PRINT '---- HTML BODY ----'

    PRINT @htmlBody

    EXEC sp_OAMethod @ssh, 'ChannelSendClose', @success OUT, @channelNum
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    EXEC sp_OAMethod @ssh, 'Disconnect', NULL

    EXEC @hr = sp_OADestroy @ssh


END
GO