UDP 27005
Synopsis
- UDP port 27005 is used by Valve/Steam game clients as the default client port.
- GoldSrc, Source, and Source 2 titles bind to 27005 for client-side game traffic and handshake with servers; examples include Counter-Strike 1.6, Counter-Strike: Source, Counter-Strike: Global Offensive/Counter-Strike 2, Team Fortress 2, Left 4 Dead 2, and Dota 2.
- In these games the port can be explicitly set via the -clientport (or +clientport) launch option, and if 27005 is in use, clients often fall back to 27006 or 27007.
- Servers for these games typically listen on other ports (commonly UDP 27015 for game traffic and 27020 for SourceTV), so 27005 is primarily observed on the client side.
- Steam’s own networking guidance includes this within the UDP 27000–27031 range used for Steam game traffic.
Observed activity
Last 30 days
Detailed chart