Re: [BUG] --map-guest-addr target resolved once at startup; host network change kills the mapping silently and permanently

[Stefano Brivio <sbrivio@redhat.com>]

Yuxi, thanks for the report.

I think David and Paul already covered the main points here, but I have
a couple of details:

On Sat, 25 Jul 2026 09:28:14 -0700
Yuxi Liu <yuxi_liu@berkeley.edu> wrote:

> Expected
> --------
> One of:
> 1. pasta re-resolves the mapping target when the host's addresses
> change, or

This is the plan, essentially. For the moment:

> 2. the mapped route fails loudly (RST) instead of silently, or

...we will reset the connection if our connect() attempt fails, or at
least that should be the intention, and I'm fairly sure it works.

So the route to the destination (via your default gateway, I suppose)
is actually valid, packets are forwarded, but they just end up nowhere
on your host, correct?

If that's not the case, then it's something we should fix.

> 3. the man page warns that the mapping dies permanently on host
> network change.

This would be a welcome change for the moment anyway, it might take
months before we get to 1., so feel free to submit a patch for the man
page if you have a moment.

Note that there's a pending patch being reviewed for --map-guest-addr,
at:

  https://archives.passt.top/passt-dev/20260727040946.105277-1-david@gibson.dropbear.id.au/#r

so you would probably need to integrate your changes with it. At the
same time the additional note could form its own paragraph at the end.

I routinely fix up trivial conflicts while merging changes, so, if it's
its own paragraph, you don't really need to take care of them.

> Laptops are a mainstream platform for rootless podman. A silent,
> permanent route death on every wifi change is a serious defect for
> them.

Absolutely. We have a ton of reports about those use cases, see:

  https://github.com/podman-container-tools/podman/discussions/22737#discussioncomment-9478727

as well. The implementation is in progress but by no means trivial. Let
us know if you want to contribute to it, by the way.

-- 
Stefano