The previous change to pad the server browser query A2S_INFO packets has triggered some aggressive Anti-DDoS filters for some games. This change was made to address a reflection amplification attack in the protocol. So it looks like we will need to address the vulnerability by securing the response with a challenge, in the same way that the A2S_PLAYERS and A2S_RULES queries work. We'll be releasing a new client soon that sends the small A2S_INFO packets again, but also understands how to reply to a server that replies with a challenge instead of the data. This protocol does make it more complicated to write a custom client for the protocol (although not drastically so), and means that the query traffic cannot be trivially filtered at the edge. Unfortunately, it looks like in the current environment, that is what we need to do.
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