Re: why multi-hop icmp redirects to 0.0.0.0 on 13.0 ?

From: Bjoern A. Zeeb <bz_at_freebsd.org>
Date: Sat, 04 Dec 2021 16:34:32 UTC
On Sat, 4 Dec 2021, Kurt Jaeger wrote:

> Hi!
>
>>> 10:20:16.889185 IP x.x.x..1 > y.y.y.1: ICMP redirect z.z.z.z to host 0.0.0.0, length 48
>>
>> whoops.
>
>>> This has been stopped by net.inet.ip.redirect=0 on rtr1, but my question is:
>>>
>>> Why is rtr1 sending those multi-hop icmp redirects at all ?
>>
>> Could you elaborate on:
>
>> (a) Do rtr1 or rtr2 have a default route or are they carrying a full DFZ
>>     without default route?
>
> rtr1 runs frr, has full route, either with or without default route.

If that makes no difference then something else is wrong.


> rtr2 has only static routes, default points to rtr1.
>
>>     Assumption: if both rtr2 and rtr1 are running 13 and not 12, rtr2
>>     does have a default route and rtr1 has a full DFZ only and no
>>     default route?
>
> Seeo above.
>
>> (b) At the time this happens does rtr1 have a route to z.z.z.z ?
>>     route -4 get z.z.z.z
>
> Yes.

And that is not pointing back to the interface rtr2 is on but out
on an interface towards inet?

/bz

-- 
Bjoern A. Zeeb                                                     r15:7