Client domain in FQDN option

Greg.Rabil at ins.com Greg.Rabil at ins.com
Tue Oct 14 21:09:03 UTC 2008


Thank you for your help.  It turns out that my problem was due to a buggy client that only sent the FQDN option 81 in the Discover packet, but not the Request packet.  Once I fixed the client, everything worked just as I wanted.

Thanks again,
Greg

From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf Of Denis Laventure
Sent: Tuesday, October 14, 2008 11:54 AM
To: dhcp-users at isc.org
Subject: RE: Client domain in FQDN option

Sorry, but I don't think I can be of any help since it worked the first time I tried, I didn't had to debug it... Maybe you will have to wait for help from someone else on the list or maybe someone from ISC?

Denis

De : dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] De la part de Greg.Rabil at ins.com
Envoyé : 14 octobre 2008 11:39
À : dhcp-users at isc.org
Objet : RE: Client domain in FQDN option

Yes, I have all the settings you've identified below.  And yes, dynamic DNS updates work just fine as soon as I comment out the "option server.ddns-*" lines from dhcpd.conf.  Of course, then the updates occur using the hostname from the client and the configured option domain-name value.  I have tried with both the 3.0.6 and 3.1.0 servers with a client that sends the FQDN option both in ASCII and binary encoding.  Consistently, as soon as I add the "option server.ddns-*" settings, no dynamic DNS updates are even attempted.

Are there any additional debug settings that I can set that may shed some light on the problem?

Greg

From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf Of Denis Laventure
Sent: Tuesday, October 14, 2008 9:05 AM
To: dhcp-users at isc.org
Subject: RE: Client domain in FQDN option

I don't know what's the problem, I have those 2 lines in my global configuration for my first dhcp server (v4.0.0) and in a subnet declaration on another dhcp server for a different network (v3.1.0) and they both work and send ddns updates to my bind server.

Did you ever get ddns updates to your dns server? Do you have your zone declaration and secret key in your dhcpd.conf?

That's what I have in my dhcpd.conf about my ddns setup:

ddns-update-style interim;
ddns-updates on;

option server.ddns-hostname = option fqdn.hostname;
option server.ddns-domainname = option fqdn.domainname;

key "rndc-key" {
        algorithm hmac-md5;
        secret "XXXXXXXXXXXXXXXXXXXXXXXXXX";
};

zone zone.org.                   { primary 192.168.10.10; key rndc-key; }
zone 16.172.in-addr.arpa.       { primary 192.168.10.10; key rndc-key; }

Denis Laventure
Service des technologies de l'information
Université du Québec à Chicoutimi
418-545-5011 poste 2380

De : dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] De la part de Greg.Rabil at ins.com
Envoyé : 13 octobre 2008 14:56
À : dhcp-users at isc.org
Objet : RE: Client domain in FQDN option

This looks like what I want, but I can't get this configuration to work.  Whenever I configure the following:

option server.ddns-hostname = option fqdn.hostname;
option server.ddns-domainname = option fqdn.domainname;

Then I see no DDNS updates happening at all on the server.  My packet captures show that FQDN Option 81 is configured with a value of 'client.test.com.' with the 'S' bit set ON.  The syslog output from the server indicates that no DDNS is even attempted.  I have configured 'ddns-update-style interim'.

Is there something else that I must configure to get this behavior?

Thanks,
Greg

From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf Of Denis Laventure
Sent: Saturday, October 11, 2008 11:22 AM
To: dhcp-users at isc.org
Subject: RE: Client domain in FQDN option

You might want to check http://marc.info/?l=dhcp-users&m=115410175622600&w=2

It works well for me.

Denis

De : dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] De la part de Greg.Rabil at ins.com
Envoyé : 10 octobre 2008 17:20
À : dhcp-users at isc.org
Objet : Client domain in FQDN option

I have a question regarding the domain used for Dynamic DNS updates.  If I read the man page (and the code) correctly, it appears that the domain portion of the FQDN determined by the server is always taken from either the configured domain-name option (15) or the ddns-domain-name policy.  The hostname portion of the FQDN is derived from either the hostname option (12) supplied by the client or the leftmost label of the FQDN option (81).  That is, any domain provided by the client in the FQDN option (81) is essentially ignored by the server when performing the DDNS update.

1.  Is that correct?
2.  If so, that does _not_ violate section 4 of RFC 4702, as all references therein related to this are defined as MAY.  However, I was simply wondering if there was any plans to support additional behavior in the server to use the client's notion of the domain, or if there are any other workarounds that may be available.

Thanks,
Greg Rabil
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