bird 1.3.2 - kernel / learn / filters

[Alex Bligh]

--On 17 August 2011 21:54:57 +0200 Ondrej Zajicek <santiago at crfreenet.org> 
wrote:

> On Wed, Aug 17, 2011 at 07:59:39PM +0100, Alex Bligh wrote:
>> Is it possible either to control what routes the kernel protocol
>> learns from the kernel using "learn" by what /kernel/ protocol
>> they are (meaning the "protocol xxxx" field to the "ip route add"
>> command on linux),
>
> This is not possible - although the value of (kernel) protocol field is
> learned, it is not accessible to filters. It will be trivial to add this
> feature. But i wonder if there are any sensible use cases. Perhaps an
> import of routes from other routing daemons through kernel table?

Perhaps an explanation of the use case would be useful.

I have a separate program (not a routing daemon, but I suppose
similar) which is busy creating, numbering and deleting interfaces
and adding routes to them. I need to learn both device routes
(where the interface is numbered) and static routes pointing out
the device (where the interface is not). These get distributed
by bird into a routing protocol and sent elsewhere. My concern
is to ensure I am not picking up (and thus distributing) any
bogus routes other than those created & destroyed by the other
program.

Using the device protocol, I can mask out all the interfaces
bar these autogenerated ones because I give them a name with a
constant prefix. However, that's not posssible with routes;
the only way to tag them (short of using a different kernel
table, which is a overkill and also conflicts with some other
stuff) is by routing protocol number (in the linux kernel sense).

I don't really need this to be available to a filter, but it
would be useful if "learn" could take a parameter which was
(say) a list of (linux kernel) routing protocols. I suspect
other OS's have similar things.

-- 
Alex Bligh