How can I open a listening port for the Blizzard Downloader?

I am trying to download Diablo 3 to be ready at the release date, but I have a problem with the Blizzard Downloader. Unfortunately downloading is very slow and there is a yellow message that says "A listening port could not be opened".

I clicked help and tried to set up port forwarding as explained, but the warning message persists. How can I solve this problem?

6 Answers

According to this you need ports 6881-6999 open for peer to peer traffic. Make sure your computer and local routers have these unblocked (or at least, properly forwarded). Most routers also have a "DMZ" option for computers, which you can temporarily place your computer in for unrestricted access to the internet. Search Google for "[your router name] DMZ" to learn how to enable this.

Unfortunately, these are common bitTorrent ports and your ISP might be throttling or blocking these ports. If you go to View > Connection Info in the downloader you can see where the problem lies. Most likely only the "Direct Connections" are available and no other "peers".

Your best bet in this case would be to copy the client from a friend who has downloaded it, change your internet service provider or use a proxy.

I had this same problem, and while your question asks specifically with how you open ports, which I think the other answers do a good job describing, that didn't actually result in faster download speeds for me, and based on some comments you left it sounds like it didn't work for you either.

The following, however, did work wonders for me:

1. Open up Internet Explorer (whether it's your main browser or not).
2. Go to Tools -> Internet Options.
3. Click on the Connections tab.
4. Click the Lan settings button.
5. Uncheck the "Automatically detect settings" checkbox.
6. Restart your Blizzard Downloader. (possibly unnecessary)

After doing this and restarting the downloader, I suddenly went from truly abysmal speeds (like, 100 MB downloaded over 3 hours) to a > 800 KB/s transfer rate. Even with P2P disabled (and thus, I think, not even needing the port forwarding) I was getting these speeds. Everything else I'd tried before this, such as forwarding ports, disabling the firewall, turning off anti-virus, or enabling/disabling P2P had no effect on my actual speeds.

Your router is restricting your use of P2P downloading features. You'll need to modify your port forwarding configuration to accommodate this. Until then you're restricted to passive p2p connections.

Check out these Blizzard support pages for help:

It looks like the following ports are required: 1119, 1120, 3724, 4000, 6112, 6113, 6114, and 6881 through 6999

For instructions on port forwarding. has historically been a good resource

DISABLE peer-to peer transferring altogether, my download went from 12 hours to 3. Main reason you get about 6x more downloaders then you get uploaders. It is a nice idea but still a waste of connections.

You can find Internet Options through the control panel, this has been true since WinXP at least, and is still true for Vista and Windows 7. No need to launch IE. As another posted, disabling automatic proxy detection somehow for some reason fixed my download rate. Went from 35kb/sec to the proper 1mb/sec (my service cap). No peer-to-peer is enabled.

List of port ranges, including TCP or UDP for configuration of your router. This is the most complete list I have found.