Choosing an open source DHCPv6 client

Shane Kerr shane at
Wed Dec 23 11:34:55 CET 2009


On Tue, 2009-12-22 at 15:32 +0100, Bjørn Mork wrote:
> Shane Kerr <shane at> writes:
> > On Tue, 2009-12-22 at 14:07 +0100, Bjørn Mork wrote:
> >> * ISC:
> >> 
> >>  Don't support PD (yet).  Will be interesting when it does.  But I'm not
> >>  convinced the IPv4/IPv6 integration is a good idea.  It might help
> >>  increase development resources though, which is definitely good.
> >
> > ISC DHCP 4.1 included prefix delegation:
> >
> >
> >
> > This has been out for a year or so (apologies for the language which
> > makes it sound like it's "coming soon").
> Ah, sorry for the misinformation.  I was briefly wading through the docs
> trying to figure out how to configure it for a simple PD setup when I
> hit this part of dhcp-options(5):
>        option dhcp6.ia-pd string;
>           The ia-pd option is manufactured by clients and servers to
>           create a Prefix Delegation binding - to delegate an IPv6
>           prefix to the client.  There is not yet any support for prefix
>           delegation in this software, and this option is provided
>           informationally only.
> I stopped reading there, I'm afraid.  Just checked the 4.1.1rc1 version
> released December 8, 2009 and the 4.2.0a1 version released December 4,
> 2009 and they both contain the same text in
> {dhcp-4.1.1rc1,dhcp-4.2.0a1}/common/dhcp-options.5 

Yikes! Okay, this has been fixed in our repository and should get pushed
out with the next release.

> I guess it needs an update.  The reason I ended up in dhcp-options(5) is
> that I was unable to find any PD information in dhclient.conf(5).  I see
> now that it is mentioned in the dhclient(8) manual.  But I'm still in
> the blue wrt howto convert this very simple wide-dhcpv6 config to ISC
> dhclient config: 
> interface ppp0
> {
>   send ia-pd 0;
>   script "/etc/wide-dhcpv6/dhcp6c-script";
> };
> id-assoc pd {
>         prefix-interface eth0 {
>                 sla-id 0;
>         };
> };
> Do you happen to have a PD example configuration for dhclient?

In doc/examples, there's 'dhcpd-dhcpv6.conf', which is a general
example of various kinds of syntax, static and dynamic prefix
delegation is in there.

We do intend to make an overall "PD howto" also.

> > Also, the IPv4/IPv6 integration is not an artifact of good design, but
> > done because it was the simplest way to get IPv6 support in quickly.
> >
> > We are planning on integrating DHCP into BIND 10, which is currently in
> > active development (on the DNS side at least).
> I guess you see the integration advantages.  I'm afraid I don't.  There
> is also a DHCP server in FreeRADIUS nowadays.  Don't really see the
> point of that either.

BIND 10 is going to be a set of co-operating processes, a bit like
Postfix. So "integration" means a separate set of processes that uses
the same underlying mechanism as the DNS side. The advantage is that all
server-side daemons have a certain set of similar needs: configuration,
logging, and so on, and rather than re-invent this or have duplicate
code, we simply make it part of the same product. 

Since BIND 10 is modular, being "integrated" doesn't mean you have to
run everything. So if you really just want a DHCPv4 server, you only
carry the code and memory footprint necessary to run the DHCPv4 server,
not also the DHCPv6 server and the dynamic DNS server and so on.


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