overriding static routes in FreeBSD

[Alexander Zubkov]

Hi,

I think it is intentional so that bird should not meddle with "foreign"
routes. In Linux, for example, it uses it's own protocol label and
does not touch
other routes. It can import them, but does not change them.
In your situation, I think the optimal solution is to have your
original default routes with some high metric, so that bird's default
should override it later. In that case it will not need to replace
routes it does not own, because usually you can have routes with the
same prefix but different metrics simultaneousely in your routing
table.


On Tue, Jun 15, 2021 at 11:41 AM Kajetan Staszkiewicz
<vegeta at tuxpowered.net> wrote:
>
> Hello group,
>
> I'm running BIRD on FreeBSD and I came across a problem with overriding
> static routes created outside of BIRD. The situation is that for
> installation of the operating system (contacting repositories, Puppet
> and some other services) system needs to have a static default gateway
> but once the system is fully installed it runs BIRD and talks BGP to
> core routers.
>
> Default routes are created with the usual FreeBSD method:
> [9:08:14] hwlb-awtest-01 ~/ # cat /etc/rc.conf.d/routing
> defaultrouter="1.2.3.4"
> ipv6_defaultrouter="a::f"
>
> Routes are created with UGS flags:
> [9:11:17] hwlb-awtest-01 ~/ # netstat -rn | grep default
> default   1.2.3.4     UGS      public
> default   a::f        UGS      public
>
> Once BIRD is started the log gets full of those messages:
> Jun 15 08:57:32 hwlb-awtest-01.ndco.ig.local bird[2216] KRT: Error
> sending route 0.0.0.0/0 to kernel: File exists
> Jun 15 08:57:50 hwlb-awtest-01.ndco.ig.local bird6[2213] KRT: Error
> sending route ::/0 to kernel: File exists
>
> I've looked at BIRD's source and I understand that BIRD replaces routes
> using krt_replace_rte and krt_send_route, and that all routes managed by
> BIRD have RTF_UP | RTF_PROTO1 flags. Those are not the flags created by
> `route add` on FreeBSD by default. However if I make default routes with
> those flags via `route add default 1.2.3.4 -proto1 -nostatic`, BIRD will
> happily replace them.
>
> Kernel protocol is configured with "learn" option.
>
> Is this a bug? Or should I just adjust the static routes to be
> BIRD-compatible?
>
> --
> | pozdrawiam / greetings | Powered by macOS, Debian and FreeBSD |
> |  Kajetan Staszkiewicz  |  www: http://vegeta.tuxpowered.net   |
> `------------------------^--------------------------------------'
>