dhcpcd-discuss

On 09/03/2018 13:13, Roy Marples wrote:
> On 08/03/2018 22:31, Brenden Blanco wrote:
> > > I'm running dhcpcd on a single interface in dual stack and IPv6-PD.
> > > Archlinux recently updated to 7.0.1 which broke IPv6 for me.
> > >
> > > After doing git bisect I found that commit ef53a17 (DHCPv6: listen on 
> > > all
> > > IPv6 addresses for active interface) responsible for this. Reverting 
> > > it on
> > > master solves the issue for me.
> > >
> > > I'm running archlinux with systemd-networkd for everything else but 
> > > the WAN
> > > interface.
> > > I can provide additional information if needed.
> >
> > I came across this thread while googling, and I believe that I am
> > hitting it as well. Specifically, it seems that my ISP (wave-G
> > broadband) is ignoring any solicit requests that do not come from port
> > 546 (packets are blackholed).
> >
> > Besides reverting ef53a17, could we consider introducing a config
> > option to allow the source port to be overridden, as a buggy ISP
> > workaround?
>
> The problem here is simple, but hard to solve.
> dhcpcd is not running in master mode, which means you could have >1 
> dhcpcd instance handling dhcp6 on different interfaces. However, only 
> one instance can actually bind the unspecified address to port 546. As 
> we don't know which instance can win, we just don't bind it in non 
> master mode, so the source port is random.
>
> We could bind to the LL address for the interface, but that in turn 
> means we *may* not be able to unicast messages to the DHCPv6 server if 
> it's asking for that.
> So a short term fix would be to ignore the unicast option in non master 
> mode and bind to the LL address.

Fixed here hopefully:
https://roy.marples.name/git/dhcpcd.git/commit/?id=3715c0a1b3fbb92dd08d07d5f6e8f3afa833ff0d

Can you both please test it and report back?

Roy