FactoryPMI no longer works after joining a Windows Domain

I just worked with an integrator who lost connectivity to a FactoryPMI server (Windows XP SP2 computer) after joining it to a Windows 2003 domain (Small business server). Here were the symptoms:

  1. The machine could run FactoryPMI locally via it’s non-loopback address
  2. Other computers could ping the FactoryPMI computer and could remote desktop into it.

In this particular case, the Windows Firewall was blocking access to the port. Although the firewall was disabled earlier, joining the domain made the client computer (FPMI server) adhere to the domains administrative policies. In particular, the group policy specified for the firewall to run - a policy that can’t be changed at the workstation level.

The fix is to go to Control Panel -> Windows Firewall -> “Exceptions” tab then click “Add Port”. You now type a name (FactoryPMI, for example) and the port that you wish to open in the firewall (8080 by default).

FactoryPMI only requires TCP/IP and a single TCP port to communicate on. Even though this problem seemed like a Windows problem, it ended up coming down to a fundamental networking issue.