Network access from WSL2 -> windows host stopped working; How do I find out where the blockage is?

[stevesutton-hds]

System:

Host: Windows 11, with all updates installed.
Software: mysql8.2
Guest: Ubuntu 22.04.5 LTS

Problem:

For the last year+, I have been connecting to the mysql service in the host from WSL2 via 172.26.240.1:3306 successfully. I've been out of office for 2 weeks, but made no configuration changes. Now, when I try to connect, the connection times out with no response.

Note that I can still connect to the DB, successfully, from mysql workbench in the windows host. I can also connect successfully to the outside Internet from the guest. It is specifically the connection from the guest to the host that has stopped working.

The issue appears to be that something is now stopping the connection from the guest to the host.

Where do I start looking to find out what is blocking the connection.

[github-actions]

Logs are required for review from WSL team

If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'.
Otherwise, please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs

Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The script will output the path of the log file once done.

If this is a networking issue, please use collect-networking-logs.ps1, following the instructions in Collect WSL logs for networking issues

Once completed please upload the output files to this GitHub issue.

See Collect WSL logs (recommended method).

If you choose to email these logs instead of attaching them to the bug, please send them to wsl-gh-logs@microsoft.com with the GitHub issue number in the subject, and include a link to your GitHub issue comment in the message body, and reply with '/emailed-logs'.

[stevesutton-hds]

/question

[github-actions]

Diagnostic information

Found '/question', adding tag 'question'

[OneBlue]

@stevesutton-hds: That might be caused by a firewall or AV change.

Does using the localhost relay (127.0.0.1:3306) instead work ? That should be a more reliable way to access the WSL2 port.

[stevesutton-hds]

Connecting to 127.0.0.1 returns immediately with "ERROR 2003 (HY000): Can't connect to MySQL server on '127.0.0.1:3306' (111)" - my understanding of WSL is that 127.0.0.1 is just connected back to the guest, not the host, and that it's the 172.26.240.1 that is NATted to the host, so I wouldn't expect 127.0.0.1 to work, as I'm not running mysql on the guest.

I haven't knowingly made any changes to firewall or AV in either host or guest. I'm guessing that something in Windows has been updated in the 2 weeks of down time, but I simply don't know where to look.

The WSL network diagnostics tcpdump output showed packets being sent out to 172.26.240.1:3306 with nothing coming back. I'm just stumped on where to look next, on the host side, to see what might be blocking this, but to reiterate, I've made no deliberate configuration changes to firewall or security settings which may explain this.

[stevesutton-hds]

I've finally managed to fix this my manually configuring the firewall to allow connections! I still don't know why it stopped working, but I'm leaving this here in case it helps anyone else.

Solution: from https://learn.microsoft.com/en-us/sql/database-engine/configure-windows/configure-a-windows-firewall-for-database-engine-access?view=sql-server-ver17

[WINDOWS]-R to run command "wf.msc"

Select "inbound rules" Then click "new rule" from actions.

Added a port rule to allow TCP connection to port 3306.

I can now connect to mysql server on the host OS from the guest OS. I'm guessing this is a microsoft update fubar, because I didn't make any deliberate changes to block those connections, it just stopped working.