Re: "accept_ra 1" vs "accept_ra 2" in interfaces configuration-file

[Martin T <m4rtntns@gmail.com>]

On Wed, Aug 22, 2018 at 2:02 AM Andy Smith <andy@strugglers.net> wrote:
>
> Hi Martin,
>
> On Wed, Aug 22, 2018 at 01:06:32AM +0300, Martin T wrote:
> > In addition, "accept_ra" with a value of 2 should ensure that RA
> > messages are accepted even if forwarding for that interface is
> > enabled, shouldn't it?
>
> Yes, it should.
>
> That's the way it's documented and our use case is what it's meant
> to serve, so if it's not behaving that way for you then I think it
> is a bug and should be reported upstream in the kernel bugzilla.
>
> Cheers,
> Andy
>

Hi Andy,

I did some additional tests and made following observations:

1) For IPv6 one can't enable/disable routing for specific
interface(s). It is either off(/proc/sys/net/ipv6/conf/all/forwarding
is 0) or on(/proc/sys/net/ipv6/conf/all/forwarding is 1).
2) /proc/sys/net/ipv6/conf/<INTERFACE_NAME>/forwarding controls simply
if interface sends out RS messages and accepts RA messages

Also, I found a post from David Miller in 2001(!) where he told pretty
much the same: https://bugzilla.redhat.com/show_bug.cgi?id=38533

This means that I set the accept_ra in interfaces file to 1 for
eth0(ISP-facing interface) and added those two lines to sysctl.conf:

net.ipv6.conf.all.forwarding=1
net.ipv6.conf.eth0.forwarding=0


Martin