Re: can't add a /24 blackhole route with a /32 loopback

From: Alexander Chernikov <melifaro_at_FreeBSD.org>
Date: Wed, 14 Jun 2023 09:56:57 UTC

> On 14 Jun 2023, at 10:42, Alexander Chernikov <melifaro@freebsd.org> wrote:
> 
> 
> 
>> On 14 Jun 2023, at 10:06, Benoit Chesneau <benoitc@enki-multimedia.eu> wrote:
>> 
>> I forgot oto add the error message , sorry. 
>> 
>> When I try to set the theblackhole flag I get the following error:
>> 
>> ```
>> route: writing to routing socket: Operation not supported
>> change net 1.1.1.0 fib 0: Operation not supported
>> ```
This looks like a route change request. Could you share the command as well?
> Interesting. Could you also share full ifconfig output or at least ifconfig for each of the loopbacks?
> If the output contains something you’re not comfortable sharing in the ML, you could consider sending it directly to my email.

>>> netstat -4rnW |grep -e "1.1.1"
>>> 1.1.1.0/24 127.0.0.1 USB 14 16384 lo0
>>> 1.1.1.1 link#9 UHS 26 16384 lo1
^^
I see both the blackhole route and the loopback /32 here.

Could you try:
1) removing the 1.1.1.0/24 route
2) removing the 1.1.1.1/32 from the lo1
3) provide the output for `route -n get 1.1.1.0/24`
4) provide the output for `route -n get 1.1.1.1/32`
5) assign 1.1.1.1/32 to lo1
6) provide the output for `route -n get 1.1.1.0/24`
7) provide the output for `route -n get 1.1.1.1/32` 
8) provide the output for `route add -net 1.1.1.0/24 -blackhole`

>> 
>> 
>> ------- Original Message -------
>> On Wednesday, June 14th, 2023 at 10:38, Benoit Chesneau <benoitc@enki-multimedia.eu> wrote:
>> 
>> 
>>> Hi,
>>> 
>>> Thanks for your answer. I'm using Freebsd 13.2 latest version:
>>> 
>>> $ uname -srm
>>> FreeBSD 13.2-RELEASE amd64
>>> 
>>> I edited the filtred result of the table since it has a full view:
>>> 
>>> netstat -4rnW |grep -e "1.1.1"
>>> 1.1.1.0/24 127.0.0.1 USB 14 16384 lo0
>>> 1.1.1.1 link#9 UHS 26 16384 lo1
>>> 1.1.1.2 10.3.1.1 UGH1 15 9000 vlan2212
>>> 1.1.1.2 10.3.1.1 UGHS 16 1500 vlan2212
>>> 1.1.1.2 10.3.1.1 UGHS 25 9000 vlan2212
>>> 
>>> 
>>> Also I forgot to mention that the ethernet driver is MLX4EN(4):
>>> 
>>> mlx4_core0@pci0:8:0:0: class=0x028000 rev=0x00 hdr=0x00 vendor=0x15b3 device=0x1007 subvendor=0x103c subdevice=0x22f3
>>> vendor = 'Mellanox Technologies'
>>> device = 'MT27520 Family [ConnectX-3 Pro]'
>>> class = network
>>> Corrected = Advisory Non-Fatal Error
>>> 
>>> 
>>> 
>>> Hope it helps,
>>> 
>>> 
>>> Benoît
>>> ------- Original Message -------
>>> On Wednesday, June 14th, 2023 at 10:29, Alexander Chernikov melifaro@FreeBSD.org wrote:
>>> 
>>> 
>>> 
>>>>> On 14 Jun 2023, at 07:05, Benoit Chesneau benoitc@enki-multimedia.eu wrote:
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> When I setup a loopback to a /32 , I can add a /24 as a blackhole route anymore. I can only create a /24 attached to this looopback. Ie.
>>>> 
>>>> Could you add a bit more context?
>>>> What is the FreeBSD version (uname -srm)?
>>>> What does 'route add 1.1.1.0/24 -blackhole’ show?
>>>> Could you also share netstat -4rnW and ifconfig output (maybe privately)?
>>>> 
>>>>> when `lo1` is set to `1.1.1.1/32` I cant create a blackhole route to `1.1.1.0/24` using the command : `route add 1.1.1.0/24 -blackhole` . Is there any reason for it? The idea is to be able to advertise the prefix `1.1.1.0/24` via BGP (bird) and use 1.1.1.1/32` as a loopback distributed to other nodes using OSPF. I can probably make the loopback a /24 used by bird but what would be the other way to do it?
>>>>> 
>>>>> Benoît
>