I figure @gopher.ny can probably give out a quick yes/no to this question, and I know that opening an unsolicited UDP server port isn't on the list of things-to-do, but I'm wondering if we can customize a HubAction to listen for a response from a device on a specific port before its time-out is called.
A driver I'm working on sends all of its responses to port 8888 on the hub, which obviously, the hub won't hear since it's not listening on that port.
My guess would be they use an iptables firewall to lock down inbound ports so while not impossible it would be challenging to be able to do it with a user configurable port as you'd have to update iptables dynamically. That could open up all sorts of issues, plus would mean there's no longer a "standard" setup across hubs.
I don't see why they couldn't do a set UDP listen port though, like they do with HTTP for 39501 (I think?).