Re: IPv6 and DNS

[peter@chubb.wattle.id.au]

>>>>> "Rick" == Rick Thomas <rbthomas@pobox.com> writes:

Rick> On Jul 12, 2011, at 12:30 PM, Laurence Hurst wrote:

>> I am only aware of using DHCP with DNS to achieve what I currently
>> do wrt reliable, cross-device, forward and reverse host lookups but
>> was wondering if there was a way to take advantage of IPv6's
>> stateless configuration to get the same end. Looking at the
>> research I've done so far it's not looking good since the stateless
>> addresses are not guaranteed - I found one document referring to
>> Windows specifically randomising IPv6 addresses rather than using
>> the MAC (no idea if this is default or configurable).
>> 

Rick> I've been doing essentially this (what you propose) for over a
Rick> year, using a tunnel from SIXXS.

Rick> What I've found is:

Rick> +) SLAAC does not interact automatically with DNS or
Rick> DHCP/DHCPv6.  That's up to you.

Rick> +) Manually entering IPv6 addresses into DHCPv6 or DNS tables is
Rick> no harder than the same job for IPv4 addresses.  The only
Rick> difference is that the addresses involved are not assigned by
Rick> you, the admin -- they are the addresses discovered by SLAAC.

This is the killer for me.  I want to be able to plug something into
the network (usually an embedded board, with no console), and then be
able to ssh to it by name.  For IPv4, the dhcp client on the board
requests a unique host-id, which is then automatically put into DNS
using ddns.  And I can track what it is by looking in the DHCPD logs
if something goes wrong.

With stateless configuration, there is no log of what is assigned, and
there is no way for an authoritative agent (i.e., dhcpd for IPV4) to update
the DNS tables.  And the IPv6 security extensions mean that one cannot
predict the IPV6 address from the known MAC address.  In fact, there's
no straightfoward way to tell that something's plugged into the
network and is now addressable.

Peter C