Local server running in wsl2 not available via host

[henryfoster]

Windows Version

10.0.22621.2428

WSL Version

1.2.5.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

5.15.90.1

Distro Version

Ubuntu 22.04

Other Software

No response

Repro Steps

• start a local webserver in wsl (python, node, php)
• open a browser on the host and open 127.0.0.1:port

Expected Behavior

• the server running in wsl should be available and serve the page using 127.0.0.1:port

Actual Behavior

• browser shows a connection error
• localhost:port works but 127.0.0.1:port does not

Diagnostic Logs

No response

[chanpreetdhanjal]

Could you please follow the steps below and attach the diagnostic logs? https://github.com/microsoft/WSL/blob/master/CONTRIBUTING.md#collect-wsl-logs-for-networking-issues

[lightify97]

I'm having the same issue. I have attached my logs.
WslNetworkingLogs-2023-10-28_12-28-11.zip

It was working previously but suddenly stopped. One possible issue might be latest windows update. (KB5031455)

[Canowyrms]

localhost:port works but 127.0.0.1:port does not

I think WSL resolves localhost to its IPv6 address ([::1]) and the web server is binding to that by default, hence why http://localhost/ works but http://127.0.0.1/ does not. Try it again, but this time, in your browser, try http://[::1]/. Bet that works.

Alternatively, on the host, you can use the following command in PowerShell to check which IP address your web server is bound to:

PS> netstat -ano | findstr ":80"
  TCP    [::1]:80               [::]:0                 LISTENING       17668

If you want your web server on IPv4 (i.e. 127.0.0.1), pass it 127.0.0.1 instead of localhost.

I'm not sure how to bind a simple web server to IPv4 and IPv6 at the same time. I would also like localhost to resolve to its IPv4 and IPv6 address.

[keith-horton]

Hi there.
Can you verify that you have your webserver listening on 127.0.0.1? The above shows that there's not a socket listening at that address, on that port #. By default, localhost will resolve the IPv6 address first. (Which appears why that works for your setup - since there's an IPv6 loopback listener).

[microsoft-github-policy-service]

This issue has been automatically closed since it has not had any activity for the past year. If you're still experiencing this issue please re-file this as a new issue or feature request.

Thank you!