It's a custom UDP query class.

Download and put this file in your System folder:

http://emac.dfbgaming.com/eMac_UdpQuery.u

Open up UnrealTournament.ini and find [Engine.GameEngine]

Find the lines like this:

ServerActors=IpServer.UdpServerQuery
ServerActors=IpServer.UdpServerUplink MasterServerAddress=unreal.epicgames.com MasterServerPort=27900
ServerActors=IpServer.UdpServerUplink MasterServerAddress=master0.gamespy.com MasterServerPort=27900
ServerActors=IpServer.UdpServerUplink MasterServerAddress=master.mplayer.com MasterServerPort=27900

and replace it with:

ServerActors=eMac_UdpQuery.CoolDeal
ServerActors=eMac_UdpQuery.CoolDeal2 MasterServerAddress=unreal.epicgames.com MasterServerPort=27900
ServerActors=eMac_UdpQuery.CoolDeal2 MasterServerAddress=master0.gamespy.com MasterServerPort=27900
ServerActors=eMac_UdpQuery.CoolDeal2 MasterServerAddress=master.mplayer.com MasterServerPort=27900

The eMac_UdpQuery does fix the \secure\ server crash hack (or at least it should?).  So if you use cheat protection that fixes that- don't worry when you replace the ServerActors lines.