[mythtv-users] Mythbackend does not bind to IP addresses of interfaces without carrier

[Florian Evers]

Hi Joseph,

thanks for your reply! :-)

Am Montag, 24. Juni 2013, 16:57:43 schrieb Joseph Fry:
> > I have the problem that mythbackend does not bind to the desired IP
> > address
> > (configured via mythtv-setup) if the related interface shows NO-CARRIER in
> > "ip
> > link show", i.e., has no cable connected to it. This "problem" relates to
> > ethernet ports and to bridges.
> 
> I swear this was discussed in the past but for the life of me I can't find
> it.

Okay. Would be interesting to know if there is a reason for this behavior... 
whether it is intentional that mythbackend behaves in this way, or if this 
should be fixed.

> What it sounds like your doing is using the server ports in lieu of a
> switch, which should work for most things, but it's a bit of a kludge.
>  Personally, I'd spend a couple of dollars and get a cheap 5 port switch,
> or a residential gateway router with built in switch.

Yes, this would be a "solution". At least, this is a common setup that would 
not be affected by this behavior. However, the mainboard of my floor box already 
has 4 internal ethernet ports (e1000e), so adding a switch would be overkill.

> Dummy interfaces are on dirty hacks... this is exactly the scenario that
> they were made for (giving a standalone machine an addressable IP).  Now I
> don't know if putting one in the bridge would be considered a "dirty hack",
> but I wouldn't suggest putting it in the bridge anyway.

Okay, thanks. I solved this issue by simply adding an unconfigured dummy0 
interface to the bridge. This pulls the bridge "UP LOWER_UP" from the very 
beginning. Mythbackend binds to the IP address of the bridge, which is what 
was intended.

To summarize, one needs to fiddle around with a dummy device! However, I would 
instead expect that the mythbackend immediately binds to the IP address I tell 
it to use. Instead of this, it fails silently. It could abort or at least 
print a warning message to the logs.

To repeat, the affected interface is "UP" (bot has NO-CARRIER), the IP-address 
is set, and this IP address can be bound to without any problems. Other 
deamons are able to bind to this IP address as well. Why does mythbackend 
refuse to bind as well?

Again, thanks for your help :-)
Florian