[Dnsmasq-discuss] dnsmasq can be tricked to send invalid RAs
simon at thekelleys.org.uk
Sun Jan 5 17:39:03 GMT 2020
On 05/01/2020 13:25, Michal Zatloukal wrote:
> I recently decided to move my dnsmasq+6in4 tunnel setup from Raspbian
> to the latest Ubuntu. To keep a long story short, after some
> (mis)configuration I ended up with an interface with an IPv6 GUA, but
> with no LLA  (a bug/oversight in netplan, I guess ). dnsmasq
> does not protest this and will send RAs sourced with GUA, which will
> fail validation according to RFC 4861, section 6.1.2.
> Not really a problem for my case (AFAIK, an interface should never
> lose/stay without its LLA) , just thought you should know.
>  Should be reproducible by:
> ip addr add dev <device> 2001:db8::1/64
> ip -6 addr flush dev <device> scope link
> Then for dnsmasq config, use
>  https://bugs.launchpad.net/ubuntu/+source/netplan.io/+bug/1810971
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss at lists.thekelleys.org.uk
I don't seem to be able to reproduce this easily, the
ip -6 addr flush ....
either doesn't delete the LL address, or it gets added back in very
should fix the problem is and when it occurs.
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