limayaml/defaults.go: allow automatic UDP forwarding

[AkihiroSuda]

Fix #4040

[jandubois]

Thanks, LGTM

I think the limitation to TCP was intentional, as most users would not want/need UDP forwarding, and by enabling it by default we may unintentionally create UDP listeners on the host, blocking the ports for other instances or applications.

It is easy enough to opt-in to UDP forwarding by adding a rule in the template; the defaults are meant to cover the common use cases.

I don't have strong opinions on this, but since it may affect older instances, I don't think it should be back-ported to Lima 1.x.

[balajiv113]

LGTM 👍

At that time we didn't want to allow UDP for all so it was optin but it makes sense now

[jandubois]

At that time we didn't want to allow UDP for all so it was optin but it makes sense now

I was having second thoughts right now because forwarding by default means the first instance you start would get UDP#53, and the one you start later that actually wants it won't.

But at least on my macOS 15.7 machine mDNSResponder is being started now automatically, even if you don't use vmnet, so nobody gets to forward the DNS port to the host anymore anyways, so I guess this doesn't matter.