WSL2 cannot connect to localhost when the service is running on Windows

[bingzhangdai]

Please fill out the below information:

• Your Windows build number: (Type ver at a Windows Command Prompt)
  Microsoft Windows [Version 10.0.19041.264]

• What you're doing and what's happening: (Copy&paste the full set of specific command-line steps necessary to reproduce the behavior, and their output. Include screenshots if that helps demonstrate the problem.)
  I am using an HTTP proxy (ShadowSocks) on windows which is listening on localhost port 1080. Then, I want the command in WSL2 to go through that proxy.
  

• What's wrong / what should be happening instead:
  curl: (7) Failed to connect to 127.0.0.1 port 1080: Connection refused

• Strace of the failing command, if applicable: (If some_command is failing, then run strace -o some_command.strace -f some_command some_args, and link the contents of some_command.strace in a gist here).

• For WSL launch issues, please collect detailed logs.

In WSL1, all things are fine. In WSL2 I could connect to the HTTP proxy through my Windows IP. I believe it is caused by WSL2 running in a separate VM.

[bingzhangdai]

To simplify the issue, I will show the telnet result, 172.21.80.1 is the Windows IP on WSL switch.

[nunix]

hi,
the issue here is that while Windows can see the localhost ports of WSL, the inverse in not true by default.
The ports forwarding are from WSL to Windows. If you do a netstat -an | grep 1080 on WSL, it should return nothing.
However, when you pass it trough the Gateway (WSL switch), it will reach it.

Going forward, you can create a tunnel from Windows to WSL if you need/want to use localhost in your proxy (see: netsh interface portproxy command)

Hope this helps.
WSL Corsair

[bplasmeijer]

See also #5131
@nunix do you see this as default behavior with the portproxy on WSL?

[bingzhangdai]

Thanks for the reply. I notice that many related issues are all about the network between the two systems. I can create a tunnel or proxy for this. But may I know if the WSL team has a specific plan or eta for the network improvement? Thanks.

[nunix]

let's wait for Build (and here I really am like you, I'm waiting on news) and see if something will done.
@bplasmeijer I remember the SSH, actually right now, netsh is what I use for many of my demos.

still, I do agree with you that the "reverse forwarding" from Windows to WSL2 would be a great improvement

[bplasmeijer]

let's wait for Build (and here I really am like you, I'm waiting on news) and see if something will done.
@bplasmeijer I remember the SSH, actually right now, netsh is what I use for many of my demos.

still, I do agree with you that the "reverse forwarding" from Windows to WSL2 would be a great improvement

cc: @craigloewen-msft @benhillis @sirredbeard

[gencer]

hi,
the issue here is that while Windows can see the localhost ports of WSL, the inverse in not true by default.
The ports forwarding are from WSL to Windows. If you do a netstat -an | grep 1080 on WSL, it should return nothing.
However, when you pass it trough the Gateway (WSL switch), it will reach it.

Going forward, you can create a tunnel from Windows to WSL if you need/want to use localhost in your proxy (see: netsh interface portproxy command)

Hope this helps.
WSL Corsair

@nunix can you give us an example? For example; I am trying to access 10134 port from WSL. 10134 port is on Windows assigned by Logitech Options application. I would like to access this port from inside WSL.

Is it possible to do with the portproxy? Currently my WSL IP is: 172.27.80.1

[eromoe]

same problem , we need to use proxy on windows localhost

[fatichar]

In my case, I am unable to connect to a service running on windows on ANY IP. Always the response is:

~/tcc/network-info$ telnet  172.17.0.1 5432
Trying 172.17.0.1...
telnet: Unable to connect to remote host: Connection refused

[eromoe]

@fatichar turn off your firewall , it cost me serveral hours to get it out . This is difinitely another big problem

[bingzhangdai]

Actually, what I am looking for is something even more about proxy between WSL2 and Windows. I am expecting similar experiences like WSL1, where WSL and Windows are using the same address (at least users should not be bothered if services on WSL and Windows are listening on different addresses) and follow the same firewall rules.

If the network is not unified, why not use VM directly and using Samba to share the filesystem? WSL1 provide grate convenience compared with VM. 🤔

Am I too greedy? 😂

[nunix]

hi,
the issue here is that while Windows can see the localhost ports of WSL, the inverse in not true by default.
The ports forwarding are from WSL to Windows. If you do a netstat -an | grep 1080 on WSL, it should return nothing.
However, when you pass it trough the Gateway (WSL switch), it will reach it.
Going forward, you can create a tunnel from Windows to WSL if you need/want to use localhost in your proxy (see: netsh interface portproxy command)
Hope this helps.
WSL Corsair

@nunix can you give us an example? For example; I am trying to access 10134 port from WSL. 10134 port is on Windows assigned by Logitech Options application. I would like to access this port from inside WSL.

Is it possible to do with the portproxy? Currently my WSL IP is: 172.27.80.1

hi @gencer I would suppose it's possible indeed, but on powershell if you do a netstat -an, on which interface is port 10134 mapped?
if it's localhost, then WSL2 cannot reach it indeed, if it's bound to 0.0.0.0 then from WSL2 distro, try connecting to the :10134

Let me know the output of netstat and I will provide you the command

[gencer]

@nunix, Unfortunately it binds on localhost as follow:

  TCP    127.0.0.1:10134        0.0.0.0:0              LISTENING
  TCP    127.0.0.1:10134        127.0.0.1:50456        ESTABLISHED
  TCP    127.0.0.1:10134        127.0.0.1:50833        ESTABLISHED
  TCP    127.0.0.1:10134        127.0.0.1:56123        ESTABLISHED
  ... and vice-versa
  TCP    127.0.0.1:56123        127.0.0.1:10134        ESTABLISHED
  TCP    127.0.0.1:50456        127.0.0.1:10134        ESTABLISHED

However, we make it work on SSH/WSL by making vscode extension runing on UI side. This makes us to access localhost port and data.

[djfos]

you can access Windows port from WSL2 using your local IP like 192.168.31.66 instead of localhost, though is not elegant