Port Mapping & TCP Bridging
Port mapping and TCP bridging allows for an unused port on the proxy 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 "maps"  or "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 proxy server.
To configure the proxy server:

1. Define a new port to map on the proxy server
   
2. Choose an unused port, try, for example, port 14
   
3. Name it something like "ClockWatch Daytime Proxy".
   
4. Map the port to port 13 (the Daytime port)
   
5. Enter the domain name of an NIST server, for example "time-a.nist.gov"
   

• Set the local host to the IP or Name of the proxy server, i.e. proxy.beaglesoft.com

• Set the local port to the port you selected above, i.e. 14
  

1. ClockWatch is first started on the client and the "Set Time" button is pressed.
2. To connect to the NIST ClockWatch sends the request to the local host on the local port, in this case the proxy server, proxy.beaglesoft.com, on port 14.
3. The proxy server translates the request to make a request to time-a.nist.gov on port 13.
4. The time string is passed back to ClockWatch running on the client.