TCP Bridging

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TCP Bridging with Gateway Servers

TCP Bridging

TCP Bridging allows for an unused port on the gateway server to be configured to contact the  timeserver on behalf of ClockWatch. ClockWatch sends the request to the proxy server using the port specified. When the proxy server receives a request on that port, it "bridges"  the request to the address and port configured on the proxy server over the Internet. The response from the timeserver is then relayed back to ClockWatch.

What follows is a brief discussion on how to set some of the key parameters for the port on the gateway server.

To configure the gateway server (using aVirt Gateway Server as an example):

  1. Open the the Gateway server to administer ports 
    (Administration->Resources->Properties on aVirt's Gateway Server).
  2. Define a new port using the TCP Bridge protocol.
  3. The 'From' field should contain the name of your gateway server; in our example we use beagle_nt.
  4. Choose an unused port on the gateway server; in our example we use port 14.
  5. Specify the NIST timeserver address, to bridge the port 'To'; in our example we use
  6. Bridge the port to port 13 (the Daytime port).
  7. Save and restart the gateway server for the new bridge to begin to listen on port 14.

Resource Administration
Example of Specifying TCP Port Bridging in aVirt Resource Administration.

On the ClockWatch Options Server panel:

  • Set the local host to the IP or Name of your Proxy server acting as the gateway; in our case.
  • Set the local port to the port you selected to listen above, i.e. port 14.
  • Check the "Use proxy server option".
  • Press OK and the gateway server should be ready to handle the bridging request.

Options/Server panel
Configuring ClockWatch to talk to the gateway server on port 14.


How it Works:

  • ClockWatch is started on the client and the "Set Time" button is pressed.
  • To connect to the NIST, ClockWatch sends the request to the local host on the local port, in this case the proxy server on port 14.
  • The proxy server translates that to make a request to on port 13.
  • The time string is passed back to ClockWatch running on the client.

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Copyright 2007 Beagle Software. All rights reserved
Last reviewed March 19, 2008