Ignoring bogus route 240.0.0.0/4

[Alexander Demenshin]

On 2017-09-20 15:06, Ondrej Zajicek wrote:

> If Linux and BSD kernels does accept such routes, than it is a strong
> reason to support that in BIRD, even if only for purpose of defining
> blackhole static route.

I could not say about BSD, but in Linux this is definitely possible
(I have tried it - just to make sure).

> So it seems strange to me that FIBs like Linux kernel does
> handle it regularly (never tried that), but perhaps they expect that 
> now
> it will never be reassigned.

Well, the reason is (probably) that Linux gives you a lot of freedom
and it is up to you how to do things - apart from few things nothing
is hardcoded and nearly everything is tunable (it even allows you to
break some RFCs).

This is good as there are some cases when (re)compilation is not 
possible
nor feasible (ROM-based embedded systems, for instance), and sometimes
you have to deal with systems that are not under your control.

I would simply include a (run-time) configuration switch to enforce some
rules or to avoid them. Not a high priority task, of course, but it 
might
make sense some day...

But at the very least, the message itself should be a bit more 
informative :)

Best regards,
Alexander.