Block UDP port without firewall using VBScript

I am testing an application that communicates with a server over a UDP port and I need to block that port to make sure the application can handle it.
Problems:
1. This must be done in an automated test (which is controlled by VBScripts).
2. This must be done in Windows XP without using a firewall.

I've tried this:

Set objFirewall = CreateObject("HNetCfg.FwMgr")
Set objPolicy = objFirewall.LocalPolicy.CurrentProfile
Set colPorts = objPolicy.GloballyOpenPorts

Set objPort = colPorts.Item(9999,6)
objPort.Enabled = FALSE

      

        
        
        
      

    

but it didn't work.