[arch-projects] [netctl] Regarding commit fe5f0d6fe - "Restrict dhcpcd to IPv4"

Jouke Witteveen j.witteveen at gmail.com
Sun Jun 16 05:00:37 EDT 2013

On Sun, Jun 16, 2013 at 10:55 AM, Thomas Bächler <thomas at archlinux.org> wrote:
> Am 16.06.2013 10:35, schrieb Jouke Witteveen:
>>> What this doesn't mention is that it also reads DNS servers from Router
>>> Advertisements, which the kernel cannot do by itself. dhcpcd does not
>>> perform dhcpv6 as far as I know.
>> I'm not sure; it might do so nowadays. Does dhclient read DNS servers
>> from RAs in IPv4 mode?
> I haven't check what dhclient does, but dhcpcd is definitely not a
> dhcpv6 client.


It says it is

>>> IMO, we should remove the -4 flag from dhcpcd if IP6=stateless is set.
>> The flag was added because in most situations leaving it out causes a
>> timeout in acquiring an IPv6 lease.
>> My initial thoughts:
>> : If dhclient doesn't extract the addresses from RAs in IPv6 mode, we
>> shouldn't expect dhcpcd to do so
>> : If dhclient does, this might be a bug in dhcpcd
> dhclient != dhcpcd. dhclient has a complete dhcpv6 implementation,
> including prefix delegation, while dhcpcd is only a dhcp and ipv6 router
> solicitation client.
> My problem here is that the kernel cannot handle the extended
> information in RAs, like DNS. We need a client to do so and dhcpcd is
> the only one I know.

In that case, it would be nice if dhcpcd allowed more control over
what it does do and what it doesn't. In IPv4-only configurations, I
don't want dhcpcd to assign an IPv6 address.

- Jouke

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