Re: [BUG] Enforcing IPv6 forwarding in radvd startup script breaks some use cases

[YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>]

Emmanuel Thierry wrote:

> The RFC is consistent with this behaviour. It states that a node may send Router Advertisements while having its forwarding capabilities disabled, as soon as it sets the Router Lifetime field (AdvDefaultLifetime) to zero.
> RFC 4861 section 6.2.5:
>>    Note that system management may disable a router's IP forwarding
>>    capability (i.e., changing the system from being a router to being a
>>    host), a step that does not necessarily imply that the router's
>>    interfaces stop being advertising interfaces.  In such cases,
>>    subsequent Router Advertisements MUST set the Router Lifetime field
>>    to zero.
> 
> 
> As a conclusion, i kindly ask you to consider relaxing the constraint of having net.ipv6.conf.all.forwarding enabled. It breaks some use cases were disabling forwarding is intended and legal.

Maybe 6.2.3:
   A router might want to send Router Advertisements without advertising
   itself as a default router.  For instance, a router might advertise
   prefixes for stateless address autoconfiguration while not wishing to
   forward packets.  Such a router sets the Router Lifetime field in
   outgoing advertisements to zero.

I think it is better to send feedback to radvd upstream.

--yoshfuji