Fwd: Filter OSPF to kernel routes

Mikhail Mayorov mm at tagan.ru
Mon Aug 8 09:07:41 CEST 2022


Hi!

I am using a similar function for both IPv4/IPv6.

function isdefault()
{
     if net.type = NET_IP4 && net = 0.0.0.0/0 then return true;
     if net.type = NET_IP6 && net = ::/0 then return true;
     return false;
}

Maybe I can reduce the number of comparisons?
If I compare ::/0 with an IPv4 address, what will be the result?

On 07.08.2022 19:21, Ondrej Zajicek wrote:
> On Sun, Aug 07, 2022 at 04:24:22PM +0200, Marcus Büttemeyer wrote:
>> OK, the problem seems to have been the name of the filter. BIRD says
>> "syntax error, unexpected DEFAULT" so I renamed the filter to
>> "reject_default" and that works. What did BIRD not like about
>> "default-reject"?
> Hi
>
> BIRD syntax allows only alphanumeric characters and underscore in names,
> so default-reject is parsed as three tokens: "default", "-", "reject".
>
> You can use apostrophes for defining names with other symbols:
>   'default-reject'
>
>
>> Also, I have said filter configured as import and export filters in both
>> ospfv3 and kernel6 but the router in question still announces the default
>> route via OSPFv3. Can anybody tell me what filter I have to use in which
>> direction on which protocol so that a) the router ignores the incoming OSPF
>> default route and b) does not redistribute his default route via OSPF?
> You should use both import (for (a)) and export (for (b)) filter for OSPF
> protocol.
>
> Also note the filter should be more like:
>
>   filter default-reject {
>           if net = ::/0 then reject; else accept;
>   }
>
>
> There should be explicit accept (it should fail with error when ends
> without reject or accept), and although "::/0 ~ net" should work, it
> is kind of strange expression (it means if ::/0 is subnet or equal to
> 'net').
>
-- 

Regards,
Mikhail V. Majorov
Megalink, CEO
B.Bulvarnaya 11, Taganrog, Russia, 347913
tel work: +7 8634 431431 (ext 101)
tel mobile: +7 905 4309006

pg19.ru
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