dhcpcd-discuss

Hi Joachim

On 2014-12-29 23:18, Joachim Achtzehnter wrote:
> Is it possible to configure dhcpcd to negotiate an IPv6 address and
> related settings with a DHCPv6 server without also assigning an
> address via SLAAC to the interface? In other words, the goal here is
> for the interface to have only the DHCPv6-assigned address and the
> link-local address, but not the MAC-address-based auto-configured
> address. The DHCPv6-assigned address would be the only IPv6 address
> with global scope.
>
> Have already tried the noipv6rs option, but then DHCPv6 didn't seem to
> work. Nothing was ever negotiated. This was with version 6.6.4 using
> Linux kernel 3.10.47.

DHCPv6 requires a IPv6RA to work - nothing else will set the IPv6 
default route other than say a native IPv6 connection over PPP.
And certainly nothing else will set any prefix (subnet like route).

The RA itself contains two mutually exclusive flags, Other and Managed.
If Other is set, DHCPv6 is used just to get extra information like IPv6 
DNS.
If Managed is set, DHCPv6 is used to get IPv6 addresses as well.
If neither of these flags are set, DHCPv6 is not started.

Now, the RA message *can* also contain a prefix, like 2002:1:2::/64.
The prefix can also contain some flags (not mutually exclusive)
OnLink - the prefix is directly associated with the interface and a 
subnet like route will be created
Auto - generate a SLAAC address for the prefix.

The kicker is the all the above is *optional*.
So to now answer your question, simply ensure that all advertised 
prefixes don't have the Auto flag set and that the RA message itself has 
the Managed flag set and you're golden!

Roy