Re: DHCPv6 DDNS registration with FQDN

[Alexander Groß <agross therightstuff de>]

I have some more findings after several debugging sessions.

According to RFC 4704, section 4.2:

The Domain Name part of the option carries all or part of the FQDN of a DHCPv6 client. ... A client MAY be configured with a fully qualified domain name or with a partial name that is not fully qualified. ... To send a fully qualified domain name, the Domain Name field is set to the DNS-encoded domain name including the terminating zero-length label. To send a partial name, the Domain Name field is set to the DNS-encoded domain name without the terminating zero-length label.

According to this, Windows clients send a partial host name, e.g. "FOO", without a terminating NULL character. dhclient, on the other hand, always sends a FQDN including the terminating NULL making the value fully qualified. I found a possibly unrelated discussion about this issue here: https://bugs.launchpad.net/ubuntu/+source/isc-dhcp/+bug/1088682

As such, send fqdn.fqdn "foo.example.local." must always be a fully qualified domain name (as NULL is automatically appended), otherwise the DDNS update won't happen in the correct DNS zone.

Any idea how to achieve that given that NM always overwrites fqdn.fqdn values found in custom (merged) dhclient6.confs?

http://cgit.freedesktop.org/NetworkManager/NetworkManager/tree/src/dhcp-manager/nm-dhcp-dhclient-utils.c#n232

Thanks,

Alex
-- 
Alexander Groß
http://therightstuff.de/