Which ip addresses and/or ports/protocols do I need to block at my firewall to prevent Steam downloading updates?

I want to prevent my housemates from inadvertently downloading Steam updates when our internet access is at peak rate. They tell me there is no way to configure Steam to download updates only at specified times.

(My firewall runs Ubuntu lucid, so I know I could block the traffic if only I knew what to block.)

  • It may or may not be possible...it depends on the router model. Please post that, including if it has a version number. – KCotreau Jun 29 '11 at 17:28
  • Not sure, but where ever it connects (i don't know where that is) just add the line "<the site to block>" to your hostfile. – soandos Jun 29 '11 at 17:30
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    @soandos He is not trying to block it totally, just at times. Also, he would need to make changes to their computers. – KCotreau Jun 29 '11 at 17:31
  • @KCotreau My firewall runs Ubuntu lucid (10.04). – dave4420 Jun 29 '11 at 17:35
  • Sorry Dave, I am not a Linux guy... I was figuring home router from Best Buy. I would have looked at the manual for you and told you how, and I missed your last line in the question....my bad. – KCotreau Jun 29 '11 at 17:36

From Steam Support, Required Ports for Steam:

To log into Steam and download content:

  • HTTP (TCP port 80) and HTTPS (443)
  • UDP 27015 through 27030
  • TCP 27015 through 27030

Steam Client

  • UDP 27000 to 27015 inclusive (Game client traffic)
  • UDP 27015 to 27030 inclusive (Typically Matchmaking and HLTV)
  • UDP 27031 and 27036 (incoming, for In-Home Streaming)
  • TCP 27036 and 27037 (incoming, for In-Home Streaming)
  • 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)
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    Those downloads also include things like custom maps. Blocking those ports will make many games unplayable. – Joel Coehoorn Jun 29 '11 at 17:38
  • @PatrickM Just made an edit that should bring the answer up to date – Steven M. Vascellaro May 11 '17 at 5:26

Steam's new content system also uses TCP port 80 for updates.

Download Better, Stronger, Faster - Steam News

Even though Steam doesn't have a schedule that can be placed on automatic updates they could set all their games to not automatically update then only manually update when it's a good time.

  • My housemates insist Steam cannot be configured to only download updates manually. Do you know how to do that? – dave4420 Jan 16 '12 at 18:34
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    Open the Steam Library tab then right click -> Properties for each game. Go to the Updates tab and change Automatic Updates to Do not automatically update this game. – Jason Jan 17 '12 at 1:45

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