FreeBSD 7.1 and BIND exploit

Mark Andrews Mark_Andrews at
Wed Jul 23 00:46:48 UTC 2008

> --On Tuesday, July 22, 2008 10:27:42 -0700 Doug Barton <dougb at> 
> wrote:
> > Matthew Seaman wrote:
> >
> >> Are there any plans to enable DNSSEC capability in the resolver built
> >> into FreeBSD?
> >
> > The server is already capable of it. I'm seriously considering enabling the
> > define to make the CLI tools (dig/host/nslookup) capable as well (there is
> > already an OPTION for this in ports).
> >
> > The problem is that _using_ DNSSEC requires configuration changes in
> > named.conf, and more importantly, configuration of "trust anchors" (even fo
> r
> > the command line stuff) since the root is not signed. It's not hard to do
> > that with the DLV system that ISC has in place, and I would be willing to
> > create a conf file that shows how to do that for users to include if they
> > choose to. I am not comfortable enabling it by default (not yet anyway), it
> 's
> > too big of a POLA issue.
> >
> I just played around with it recently.  It's not that easy to understand 
> initially *and* the trust anchors thing is a royal PITA.
> Once you implement DNSSEC you *must* generate keys every 30 days.  So, I thin
> k, 
> if you're going to enable it by default, there needs to be a script in period
> ic 
> that will do all the magic to change keys every 30 days.  Maybe put vars in 
> /etc/rc.conf to override the default key lengths and other portions of the 
> commands that could change per installation.


	You need to re-sign the zone an expire period before the
	signatures expire.  You need to generate new keys periodically
	but no where near every 30 days.

	KSKs annually.   This is what the TLD's are doing and that is
	a very conservative exposure period.  In practice it could be
	multiple years between key rollovers.  The reason it is done
	this frequently is so humans don't forget what they need to do.

	ZSKs are generally weaker than KSKs but again they don't need
	to be done monthly.

> If I were to implement it, I'd write a shell script to turn the keys over and
> cron it because doing it manually every 30 days ain't gonna happen.  Too many
> ways to forget to do it.  (I did the same for the root servers so that named.
> ca 
> gets updated automagically every month.)
> But until root is signed, it's not worth it for those of us who don't have 
> dedicated staff doing dns only.

	There are solutions to the root not being signed.

	If all the TLD were signed the trust anchor work load would
	not be too great to managed by hand.

	For those that want a single trust anchor solution there
	is DLV.

	Sign your zone.  Add it to a DLV.  Ask you parent to sign
	their zone.  If you don't sign you parent has no insentive
	to sign.  This can be driven bottom up.  That is one of the
	reasons why DLV was invented to provide incentive for the
	parent zones to sign.


> -- 
> Paul Schmehl
> As if it wasn't already obvious,
> my opinions are my own and not
> those of my employer.
> _______________________________________________
> freebsd-stable at mailing list
> To unsubscribe, send any mail to "freebsd-stable-unsubscribe at"
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

More information about the freebsd-stable mailing list