How did you manage to try to connect to the ut2003master1.epicgames.com instead of swat4.available.gamespy.com (which is also defined in some *.u)? I suppose that by default settings, the game connects to the gamespy (only?). I'm not able to simulate connection to the epicgames :-/
It can be altered in Swat4DedicatedServer.ini
[IpDrv.MasterServerLink]
bAlwaysTick=True
LANPort=10489
LANServerPort=9999
CurrentMasterServer=2
MasterServerPort[0]=28902
MasterServerAddress[0]=ut2003master1.epicgames.com
[IpDrv.MasterServerUplink]
DoUplink=True
UplinkToGamespy=False
SendStats=False
ServerBehindNAT=False
DoLANBroadcast=False
Please note, this doesn't fix anything. But does create an opportunity to build a custom master server.
Wireshark faces difficulties capturing localhost packets, and the rawcap (or how is it named exactly) doesn't do it job that good neither.
I'll get an other laptop out tomorrow if I get the chance, that master server should be doable since I learned more today.
Not sure if I have enough time to finish it this weekend though (if at all), since I have a Math Test this monday, which requires some more studying.