Server doubles

[stevomitric]

Looks like you got it working but here is my answer just for the record.

Was there something added/changed in 1.2/1.3 (I didn't find anything)?

The only difference in network communication (the part that is human-readable) in 1.3 is the new "/punkbuster/" parameter that was added (compeard to 1.0), not counting 'protocol' and 'shortversion' changes ofc:

1.0
\xff\xff\xff\xffstatusResponse
\g_antilag\1\g_gametype\dm\gamename\Call of Duty 2\mapname\mp_toujane\protocol\115\scr_friendlyfire\0\scr_killcam\1\shortversion\1.0\sv_allowAnonymous\0\sv_floodProtect\1\sv_hostname\1\sv_maxclients\20\sv_maxPing\0\sv_maxRate\0\sv_minPing\0\sv_privateClients\0\sv_pure\1\sv_voice\0\challenge\1199179950\pswrd\0\mod\0

1.3
\xff\xff\xff\xffstatusResponse
\g_antilag\1\g_gametype\dm\gamename\Call of Duty 2\mapname\mp_toujane\protocol\118\scr_friendlyfire\0\scr_killcam\1\shortversion\1.3\sv_allowAnonymous\0\sv_floodProtect\1\sv_hostname\1\sv_maxclients\20\sv_maxPing\0\sv_maxRate\0\sv_minPing\0\sv_privateClients\0\sv_punkbuster\0\sv_pure\1\sv_voice\0\challenge\1199270075\pswrd\0\mod\0

There was also some more difference in the 'connect' packet with again added parameter '\cl_wwwDownload\'.

So to answer your question, No. There were no major changes that would make master-server not accept your fake server as 1.3 (assuming you changed the protocol to 118).
Here is my code i just wrote in approx. 50 lines:

		#Network module for basic UDP communication
import socket

#Time module
import time

variables = {
    'myServerAddr': ("31.14.136.83", 28965),            #Localhost refers to the local addr that is on current computer
    'masterServerAddr1': ("185.34.104.231", 20710),    #This is the master server to witch you send hearbeats
    'masterServerAddr2': ("185.34.104.231", 20700),    #This is the master server to witch you send IpAuthorize
}

sock = socket.socket(socket.AF_INET,        # Internet dedicated
                     socket.SOCK_DGRAM)        # UDP oriented
    
sock.bind(variables['myServerAddr']);    
sock.settimeout(1)    #Raise an exeption if one second passed and no request has been done

def sendStatusResponse(addr, challenge = ""):
    sock.sendto("\xff\xff\xff\xffstatusResponse\n\\g_antilag\\1\\g_gametype\\dm\\gamename\\Call of Duty 2\\mapname\\mp_toujane\\protocol\\118\\scr_friendlyfire\\0\\scr_killcam\\1\\shortversion\\1.3\\sv_allowAnonymous\\0\\sv_floodProtect\\1\\sv_hostname\\1111111111111111111\\sv_maxclients\\20\\sv_maxPing\\0\\sv_maxRate\\0\\sv_minPing\\0\\sv_privateClients\\0\\sv_punkbuster\\0\\sv_pure\\1\\sv_voice\\0\pswrd\\0\\mod\\0\\challenge\\"+challenge.replace(' ', ''), addr);

def sendInfoResponse(addr, challenge = ''):
    sock.sendto("\xff\xff\xff\xffinfoResponse\n\\challenge\\" + challenge.replace(' ', '') +"\\protocol\\118\\hostname\\1111111111111111111\\mapname\\mp_toujane\\sv_maxclients\\20\\gametype\\dm\\pure\\1\\kc\\1\\hw\\2\\mod\\0\\voice\\0\\pb\\12972288", addr)
    
def updateServerState():
    #Looking at COD2MP_s.exe 1.3 IpAuthorize is sent first but i dont think this makes any difference what so ever
    sock.sendto("\xff\xff\xff\xffgetIpAuthorize 899360599 185.34.104.231 "" 0", variables['masterServerAddr2']);
    sock.sendto("\xff\xff\xff\xffheartbeat COD-2", variables['masterServerAddr1']); 
    
    sendStatusResponse(variables['masterServerAddr1']);

#These messages are send to the master server every 60 seconds (number varies)
updateServerState()

timeStart = time.time()

while (1):
    try:
        data, addr = sock.recvfrom(1024)        
    except:
        continue
        
    if (time.time() - timeStart) > 60:
        updateServerState()
        timeStart = time.time()
        
    if data.lower().startswith("\xff\xff\xff\xffgetstatus"):
        sendStatusResponse(addr, data.lower().replace("\xff\xff\xff\xffgetstatus", ""))
        
    if data.lower().startswith("\xff\xff\xff\xffgetinfo"):
        sendInfoResponse(addr, data.lower().replace("\xff\xff\xff\xffgetinfo", "")) 
	

Simply changing the protocol from 115 (1.0) to 118 (1.3) did the trick.