[dhcwg] Re: Why draft-ietf-dhc-addr-notification-13 and not DNS update instead?

Michael Richardson <[email protected]> Mon, 18 Nov 2024 15:12:05 -0500

Newsgroups	gmane.ietf.dhc
Message-ID	<[email protected]>

Petr Menšík <[email protected]> wrote:
    > Hello,

    > I work in Red Hat as a software engineer and one of components I work on is
    > dnsmasq. It combines DNS and DHCP service into simple box. It made me think
    > how to solve IPv6 and registration of machines with SLAAC.

Thank you, many of us use it!

    > I just today stumbled on draft draft-ietf-dhc-addr-notification-13 [1]. It
    > seems nice, but I think DNS dynamic update (RFC 2136) might be a better
    > solution. When I were thinking about my home network and how to pair my
    > hostname to IPv6 address, similar way in IPv4 dnsmasq does itself
    > automatically. Because it uses DHCP, including hostname option. But in IPv6
    > most clients do not even try to use DHCPv6.

You can do that, but in the general corporate and conference networks, few to
zero machines have a Dynamic DNS update credential that they can use with a
DNS server.   Having a DHCP server update the DNS works better, and with
things like dnsmasq, that's a trivial-no-op of security.  But, IPv6 temporary
addresses are seldom (if ever according to feedback to DHCPv6 RFC8415 we got)
registered using DHCP(v6), so there is no obvious protocol to communicate
their use.   dhc-addr-notification is a compromise in essense.

is this use case not clear from the document itself?
Of course, dnsmasq, speaking DHCPv6, can receive these updates, and ideally,
yes, populate reverse DNS.

    > I thought about implementing dynamic update into dnsmasq, similar way it
    > accepts hostnames in DHCP requests. For enterprise networks it can be
    > improved significantly. TSIG signatures can provide shared password or krb5
    > authentication. Good for CEO's laptop, I suppose?

No, terrible for the CEO's laptop, because it doesn't know to speak kerberos
at the IETF network.

--
Michael Richardson <[email protected]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide

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