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We have a white list of ports on our network, and the Steam client cannot connect to the server. Which ports do I need to open to make it work?

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possible duplicate of Steam over proxy – DrFish Nov 7 '11 at 21:50
up vote 10 down vote accepted

There's a Steam Support page on this:

Your network must be configured to allow Steam access to the following ports (in order from highest to lowest priority for QoS users):

Steam Client
UDP 27000 to 27015 inclusive (Game client traffic)
UDP 27015 to 27030 inclusive (Typically Matchmaking and HLTV)
TCP 27014 to 27050 inclusive (Steam downloads)
UDP 4380

Dedicated or Listen Servers
TCP 27015 (SRCDS Rcon port)

Steamworks P2P Networking and Steam Voice Chat
UDP 3478 (Outbound)
UDP 4379 (Outbound)
UDP 4380 (Outbound)

Additional Ports for Call of Duty: Modern Warfare 2 Multiplayer
UDP 1500 (outbound)
UDP 3005 (outbound)
UDP 3101 (outbound)
UDP 28960

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I had a nearly identical answer about ready to post when you ninja'd me. :P – Ullallulloo Nov 7 '11 at 20:56
It doesn't say which are ephemeral ports and which are outbound ports. I believe UDP 27000-27015 are ephemeral. What about the rest? – Locutus Jun 26 '13 at 9:39
Ephemeral ports are assigned automatically by the TCP stack; none of these are ephemeral. They should all be outbound, with the possible exception of the MW2 one. – BlueRaja - Danny Pflughoeft Apr 22 '14 at 16:09

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