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UDP 27015

ProtocolUDP
Port27015
LabelsGoldSrc and Source engine dedicated server port

Synopsis

  • Valve Source and GoldSrc game servers (SRCDS/HLDS) commonly use UDP 27015 as the default server and query port.
  • Examples include Counter-Strike 1.6, Counter-Strike: Source/Counter-Strike 2, Team Fortress 2, Garry’s Mod, Left 4 Dead 2, Day of Defeat: Source, and Insurgency (2014).
  • The Steam Game Server Query Protocol (A2S_*), used by the Steam server browser, typically listens on UDP 27015 for these titles.
  • Unturned dedicated servers default to UDP 27015.
  • ARK: Survival Evolved servers often expose UDP 27015 as the Steam/SteamQuery port in addition to their game ports.
  • Steam client/services also use UDP 27015 within the broader 27015–27030 range for matchmaking and server discovery.
  • Security note: the Source/Steam A2S query service on UDP 27015 has been abused for DDoS reflection/amplification and has had past vulnerabilities targeted against Source-based game servers.

Observed activity

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