re-bind named to all interfaces

[Todd Snyder]

You can set interface-interval to a low number to make BIND scan for new interfaces frequently:


interface-interval

 interface-interval minutes;
interface-interval defines the time in MINUTES when scan all interfaces on the server and will begin to listen on new interfaces (assuming they are not prevented by a listen-on option) and stop listening on interfaces which no longer exist. The default is 60 (1 hour), if specified as 0 NO interface scan will be performed. The maximum value is 40320 (28 days). This option may only be specified in a 'global' options statement.

(source: http://www.zytrax.com/books/dns/ch7/periodic.html)


-----Original Message-----
From: bind-users-bounces+tsnyder=rim.com at lists.isc.org [mailto:bind-users-bounces+tsnyder=rim.com at lists.isc.org] On Behalf Of Mihai Moldovan
Sent: Thursday, April 12, 2012 10:33 AM
To: bind-users at lists.isc.org
Subject: re-bind named to all interfaces

Hello list,

I'm running bind9 on my local router which is connected to the internet via a ppp link over my ADSL modem. This link has a static IP assigned, but is not permanently up. Once a day the connection is dropped for a few seconds and re-established, which leads to the following problem:

- starting bind9 (configured with listen-on { any; };) works fine, it binds to the following interfaces: 127.0.0.1:domain (lo), 192.168.0.1:domain (br0), 85.183.67.131:domain (ppp0)
- once ppp0 goes down, bind9 will drop the binding on 85.183.67.131:domain (ppp0)
- once ppp0 goes up again, bind9 won't detect the new network topology, thus remains bound to lo and br0 only; any nameserver on the internet won't be able to contact my bind9 anymore.

Is there any way to tell bind9 to re-evaluate the network situation and bind to all new interfaces (if allowed, see listen-on)?

I have tried firing up rndc reload and rndc reconfig via the pppd if-up/if-down scripts, but neither try was successful.

Seems like the only viable solution for now is to restart bind9 completely over the init script on ifup/ifdown, but this sounds hacky and is disrupting service in a way I don't like.

Does anyone here have a similar setup and solved this (admittedly minor) problem?

If not, I'd opt for re-discovering the network topology on reload/reconfig (as a restart is flushing caches, loading all zones and discovering network topology too.)

Best regards,


Mihai



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