[pkg-dhcp-devel] Bug#731449: isc-dhcp-server: Server not removes DDNS if client releases the address.

[Axel Beckert]

Control: fixed -1 4.2.4-7
Control: tag -1 + fixed-upstream

Hi,

Holger Sander wrote:
> The bug is fixed in Debian jessie.

Marked as such. Thanks for the information.

Seems as if the following upstream changelog entry describes what has
been fixed:

- Modify the code that determines if an outstanding DDNS request
  should be cancelled.  This patch results in cancelling the
  outstanding request less often.  It fixes the problem caused
  by a client doing a release where  the TXT and PTR records
  weren't removed from the DNS.
  [ISC-BUGS #27858]

(from http://sources.debian.net/src/isc-dhcp/4.2.4-7/RELNOTES)

> Lenny works, too. I don't test squeeze.

It seems new in Wheezy. We've run into it after upgrading our DHCPd
pair from Squeeze to Wheezy. Took a few weeks until we actually
noticed it, though, but it was only a week after this bug-report had
been openend.

> If the isc-dhcp-server (ipv4) don't remove the DNS-entry, for example the
> isc-dhcp-server -6 (ipv6) can't add DDNS with the same hostname. There ist
> no request send to bind.

We ran into it with Macbook Airs with multiple USB ethernet adapters
or Macbooks switching from USB ethernet adapters to Thunderbolt
devices with an included network adapters (i.e. an external screen
functioning as docking station).

> Useing ifdown and ifup at the client, then isc-dhcp-server updates
> the ddns-entry.

Hrm, isn't calling "ifdown" equivalent to release the currently
assigned IP address?

At least switch the network interface off in MacOS X's GUI didn't
cause an update to be send to BIND and hence this happened:

Initial lease with a8:20:66:45:50:be:

Dec 17 15:52:47 stock dhcpd: DHCPDISCOVER from a8:20:66:45:50:be (colorado) via eth1
Dec 17 15:52:47 stock dhcpd: DHCPOFFER on 192.33.103.157 to a8:20:66:45:50:be (colorado) via eth1
Dec 17 15:52:48 stock dhcpd: DHCPREQUEST for 192.33.103.157 (192.33.103.254) from a8:20:66:45:50:be (colorado) via eth1
Dec 17 15:52:48 stock dhcpd: DHCPACK on 192.33.103.157 to a8:20:66:45:50:be (colorado) via eth1
Dec 17 15:52:48 stock dhcpd: Added new forward map from colorado.dhcp.phys.ethz.ch to 192.33.103.157
Dec 17 15:52:48 stock dhcpd: Added reverse map from 157.103.33.192.in-addr.phys.ethz.ch to colorado.dhcp.phys.ethz.ch

Release without DDNS entry removal:

Dec 17 15:53:50 stock dhcpd: DHCPRELEASE of 192.33.103.157 from a8:20:66:45:50:be (colorado) via eth1 (found)

Switching network adapter to 00:1e:c2:fb:85:b6:

Dec 17 15:54:34 stock dhcpd: DHCPOFFER on 192.33.100.151 to 00:1e:c2:fb:85:b6 (colorado) via eth1
Dec 17 15:54:35 stock dhcpd: DHCPREQUEST for 192.33.100.151 (192.33.103.254) from 00:1e:c2:fb:85:b6 (colorado) via eth1
Dec 17 15:54:35 stock dhcpd: DHCPACK on 192.33.100.151 to 00:1e:c2:fb:85:b6 (colorado) via eth1

No DDNS update:

Dec 17 15:54:35 stock dhcpd: Forward map from colorado.dhcp.phys.ethz.ch to 192.33.100.151 FAILED: Has an address record but no DHCID, not mine.

		Regards, Axel
-- 
 ,''`.  |  Axel Beckert <abe at debian.org>, http://people.debian.org/~abe/
: :' :  |  Debian Developer, ftp.ch.debian.org Admin
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