[Dnsmasq-discuss] Enable AdvOnLink bit on RAs

Simon Kelley simon at thekelleys.org.uk
Sun Aug 12 17:55:21 BST 2012


On 11/08/12 17:14, Gui Iribarren wrote:
> Hello,
> interested in the sweet feature of ra-names, i migrated from a
> radvd-based setup to dnsmasq 2.62
>
> unfortunately, i found out that dnsmasq doesn't set the "on-link" bit
> to 1 on the RA packet, like radvd does by default.
> (other than that, the packets are equivalent)
>
> this bit instructs host to add the prefix as a local one (i.e., ip
> route add 2001:db8::/64 dev eth0), so it considers other hosts on that
> prefix to be neighbours as well.
> With dnsmasq, hosts now recurse to using the router as a gateway
> between them, since they lack the proper route, which in turn triggers
> ICMP redirects from the gateway.
>
> Could this be changed, so that on-link bit is set to 1 by default? (i
> think it makes sense given dnsmasq normal use cases, and it's also the
> default in radvd)
> Or at least expose it as an option?
> (radvd respective option is named "AdvOnLink")

Yes, it can be changed, the existing behaviour is down to oversight 
and/or my not understanding what that bit actually did.

I was in a slight quandary about committing this change close to the 
2.63 release, but in the end I did, based in

1) It "obviously correct".
2) I tested it here and it works perfectly
3) Even if it back-fires, most production users of dnsmasq aren't yet 
using IPv6, do it won't bite them.


So,2.63rc5 is on the website and in git. It will become 2.63 on 
Wednesday or Thursday unless anyone finds a problem before then.
>
> I'm loving the entrance of dnsmasq on the ipv6 arena :D
>

It's good to get feedback on the IPv6 stuff, thanks.


Cheers,

Simon.

>



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