Re: [PATCH net-next v5] net: ipv6: Make address flushing on ifdown optional

[David Miller <davem@davemloft.net>]

From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Wed, 14 Oct 2015 13:03:41 +0200

> On Wed, Oct 14, 2015, at 12:08, Nicolas Dichtel wrote:
>> Le 14/10/2015 11:34, Hannes Frederic Sowa a écrit :
>> [sni]
>> > This sysctl is on my list to be enabled soon by default by any systemd
>> > based distribution. For that reason, could you maybe remove all the
>> I'm not sure to understand why we add a sysctl then. Or at least, why the
>> linux
>> default value is different from all standard distrib. I will be like
>> rp_filter :/
> 
> The difference is that people upgrade (in case of fedora they get a
> .rpmnew file) or install a distribution and don't wonder or have
> assumptions about old behavior. In case companies integrate kernel in
> products/appliances without a way to manage those sysctls we cannot
> simply change them as this would break assumptions for them. I think
> those are two different cases.

The thing that is similar is that people set rp_filter inappropriately
(no end host should have that knob enabled, ever, it's totally
unnecesary).  And the risk here is similar, distribution X will set it
so Y will say "we probably should set it too even though we really
don't understand it fully".

I really hate situations like this.