Re: port forwarding

From: Greg Norris (
Date: 12/04/04

  • Next message: Rainer Lay: "Re: port forwarding"
    Date: Fri, 3 Dec 2004 20:10:33 -0600
    To: Rainer Lay <>

    It sounds like you're running into Oracle's port redirection... it does
    this by default on Windows servers. The basic sequence of events is:

      1) Client connects to the database listener.

      2) Listener allocates a dynamic port, and sends back the relevant
         details... both hostname/IP-address and port number.

      3) Client reconnects to the indicated IP and port.

    Step 3 will be where the breakage occurs, as machine r is now trying to
    connect directly to w. You can address this in either of the following

      1) Set USE_SHARED_SOCKET in the registry of machine w. This is the
         simplest method, as it prevents the redirect from ever occurring.
         It's adequate in most cases, but has significant side-effects...
         most notably, all remote connections will be dropped if the
         listener is stopped or restarted.

      2) Run Oracle Connection Manager (CMAN) on either machine l or w, and
         let it handle the redirect (so the client never sees it). This
         will require changes to the database connection details, as well as
         the port you're tunnelling.

    If you have access to Metalink (Oracle Support website), just do a
    search on CMAN and/or USE_SHARED_SOCKET and you should find all of the
    necessary details with little trouble. If not, email me privately and
    I'll try to provide more specific instructions.

    On Thu, Dec 02, 2004 at 01:29:46PM +0100, Rainer Lay wrote:
    > Hi,
    > I have here a complicated setup for port forwarding. I want to forward a
    > port of a oracle database. Three computers are involved:
    > w: windows machine with oracle installed
    > r: remote, linux. Here I want to run some oracle tools
    > l: local, linux. A Box between those two
    > I want to access the database on w from r. There is no direct connection
    > between w and r. I only have a ssh tunnel from r to l.
    > To establish the connection, I startet a ssh connection to r on l and
    > forward port 11523 on r to port 1521 on w:
    > ssh -v r -R 11523:w:1521 -g -N
    > Trying to use the oracle tools on r, I cannot get the connection to w.
    > But it should work. :-)
    > Accessing the oracle port on w from l directly works without problems.
    > So there must be something wrong with the tunnel.
    > Any ideas what I am doing wrong?
    > kind regards,
    > Rainer


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