You can't know the ports ahead of time, by default. DCOM will use any number of ports in a specified range. You can, however, configure both the client and the server machine to restrict port usage to a specified range.

Check MSDN for an article entitled "Using Distributed COM with Firewalls".


>Can you tell the numbers of these ports, or where I can find information about that?
>
>>>However, when I run it using my modem connection to internet from home, I get error
>>>"OLE Error code 0x800706d3: The authentification service is unknown"
>>
>>If you connect to the internet from home using an ISP, it's possible that the ISP is blocking the port(s) needed for DCOM.