$ sysctl net.ipv4.ip_unprivileged_port_start
net.ipv4.ip_unprivileged_port_start = 1024

Here's the output for me on Ubuntu 22.04.1

Yes, that's the default (and traditional UNIX behavior.) The test starts failing when it's <= 42.

So, you're saying the test should be modified to check the range of reserved ports on the current system, rather than assuming that it will always be 42?

The test should bail out with common.skip('...') if port 42 is unprivileged, yes.

Can I take a try at this? I would write a function to find the first unprivileged port and then try to attach a process to the port just before the first unprivileged port. Then basically the same checks as before (making sure the exit code is 0, etc) Is this implementation fine?
@bnoordhuis

Go for it but I'd rather it just exits if port 42 is unprivileged. Principle of least surprise and all that.

That makes sense, I'll send in a PR in some time!

@bnoordhuis PTAL.

Please ignore the second PR, I think it got added due to me changing branches locally and pushing.

Can you link me to your PR? I can't find it for some reason.

@bnoordhuis I messed up my Git locally and had to create a new PR. I hope you can see it now?