On Mon, Jun 22, 2015 at 03:01:33PM -0400, Frank Pikelner wrote:

Hello,

In my testing it would appear for Dynamic DNS to work (update DNS A and PTR records), the Linux client hostsname needs to be FQDN (client123.domain.com) defined as one of the hostnames in /etc/hosts for the 127.0.0.1 IP as:

[/etc/hosts]

127.0.0.1 client123.domain.com client123 localhost.local localhost 172.16.5.10 client123.domain.com client123

If I have something like, dynamic DNS does not appear to work:

[/etc/hosts]

127.0.0.1 localhost.local localhost 172.16.5.10 client123.domain.com client123

The second /etc/hosts file should be correct but dynamic DNS is not working. Is there something in the implementation that requires the first case, or should just the order of the /etc/hosts entries modified so that the localhost appears second in the list?

I think this is more of a SASL or kerberos issue that requires the forward and reverse records to match.

But yes, in general with Kerberos, especially not the most recent versions, you want the DNS records to match in both directions.

Hello John,

A couple of questions, as I would really like to understand how this is working and why it fails at times. With your DHCP server config, are the clients sending the DynDNS updates directly or are the DynDNS updates managed by the DHCP server to DNS?

In my case I'm using static IPs on all of my test clients, so may need to try the same tests with DHCP.

Thank you,

Frank

On Tue, Jun 23, 2015 at 4:18 AM, John Hodrien J.H.Hodrien@leeds.ac.uk wrote:

On Mon, 22 Jun 2015, Frank Pikelner wrote:

The second /etc/hosts file should be correct but dynamic DNS is not

...

working. Is there something in the implementation that requires the first case, or should just the order of the /etc/hosts entries modified so that the localhost appears second in the list?

I have machines that do DDNS triggered from DHCP, and it works just fine without having the incorrect /etc/hosts. Indeed I just have:

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

To get the client to send the correct hostname, I use:

/etc/sysconfig/network-scripts/ifcfg-eth0: DHCP_HOSTNAME="whatever.you.want"

That makes it work perfectly for me.

jh

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If the DHCP server is posing the DDNS updates, then that is why you do not see the issues. In my case it is client through SSSD that posts the updates and is affected by the /etc/hosts entries. I need to do more testing and will post to the list if I find issues.

On Tue, Jun 23, 2015 at 9:36 AM, John Hodrien J.H.Hodrien@leeds.ac.uk wrote:

On Tue, 23 Jun 2015, Frank Pikelner wrote:

Hello John,

...

A couple of questions, as I would really like to understand how this is working and why it fails at times. With your DHCP server config, are the clients sending the DynDNS updates directly or are the DynDNS updates managed by the DHCP server to DNS?

In my case I'm using static IPs on all of my test clients, so may need to try the same tests with DHCP.

In my case it's the DHCP server that send the DDNS updates.

jh _______________________________________________ sssd-users mailing list sssd-users@lists.fedorahosted.org https://lists.fedorahosted.org/mailman/listinfo/sssd-users