[Cerowrt-devel] thoughts toward improving cerowrt's DNS and DNSSEC in the next release
ethanol at gmail.com
Mon Aug 20 15:16:08 EDT 2012
As a BIND 9 author I confess to bias on this point, but I don't agree
that BIND is an unnecessary waste of memory. MaraDNS is nice but last
I checked it didn't handle DNSSEC validation or signing, both of which
I use in my router.
Validation, at least, seems to me to be a must-have. You can't trust
DNSSEC validation done somewhere else. I don't trust Comcast,
Verizon, or AT&T never to lie to me.
Google's DNS does *not* do DNSSEC, neither does OpenDNS. Google will
return RRSIGs when you ask for them, and they've fixed their DS bug,
but it doesn't authenticate the data -- and even if it's being used as
a forwarder for a validating stub, DNSSEC will break sometimes if the
forwarder isn't validating too. (For example, one name server for a
zone has stale data with expired signatures and the others are
correct; a validating name server would know to ignore the stale data
and ask the other servers until it got something valid, but Google
will pass the stale data along unquestioningly and then your
validating stub doesn't work.)
IMHO the future we want to aim for is one where people do their own
DNSSEC validation at home, and for the moment that means BIND or
On Mon, Aug 20, 2012 at 11:43 AM, George Lambert <marchon at gmail.com> wrote:
> We have been working on DNS stuff and I will make some DNS Recommendations
> within the next couple of days - if that would help.
> Bind is an unnecessary waste of memory.
> UnBound is too slow.
> We are making custom modifications to MaraDNS to make it
> have the right low memory footprint and optimizations for a router.
> On Mon, Aug 20, 2012 at 2:25 PM, Dave Taht <dave.taht at gmail.com> wrote:
>> The ongoing DNS issues bug me. For most uses these days I disable bind
>> entirely, as the 12-20MB it uses up are better used for packets. I do
>> use it on 3800s but not on 3700v2s.
>> 0) the circular time issue (bug #113) remains a PITA. I was really
>> scarred by trying to fix that one last year and keep hoping someone
>> else will fix it...
>> 1) The luci gui has hooks for dnsmasq's "use dns servers advertised by
>> peer" and "use custom dns servers", which are not tied into the bind
>> This is confusing users. The way to do that manually is to get the
>> advertisement once, validate that those servers do NXDOMAIN and
>> DNSSEC, and toss them into forwarders.conf and enable forwarders.conf
>> 2) Going the the DNS roots with bind, is OK, but it is always faster,
>> and more reliable to use the ISP provided DNS servers, if they can be
>> trusted to send DNSSEC information. Comcast's (if you are on comcast)
>> are fast as heck. I also recently discovered that google DNS does
>> indeed do dnssec, and although much further away than comcast on the
>> networks I have access to, they are universally available.
>> So I am thinking of enabling forwarding by default to google DNS. This
>> reduces enabling forwarding to another set of servers provided by the
>> ISP, if usable....
>> I would like a test of some sort that would prove a delegated ISP's
>> DNS server was "worthy", this test would include NXDOMAIN, DNSSEC, and
>> whatever else would be required to validate it as a potential
>> forwarder to overwrite the forwarders.conf file with that information.
>> I wouldn't mind establishing a global white/blacklist of DNS servers
>> that did NXDOMAIN/DNSSEC right/wrong somewhere, either...
>> dnsmasq may gain DNSSEC by the winter, btw....
>> 3) A related problem is that when behind many walled gardens (a hotel,
>> for example), going to the DNS roots via bind doesn't work at all,
>> neither do things like google dns, and usually the forwarder is pretty
>> crappy in the first place. dnsmasq works in this scenario just fine...
>> 4) A final alternative is to drop bind by default and install it
>> optionally. While this would lose DNSSEC, and split views and local
>> delegations, it would buy the integration with dnsmasq, which includes
>> things like AAAA naming, etc., and get some memory back. (I note that
>> the OOM issues we're encountering are USEFUL to encounter in that
>> optimizing for memory use throughout the system is very important, and
>> I have similar issues on 32MB routers like the picostation/nanostation
>> even without bind)
>> Given the amount of time, energy, and money (all 0) I personally have
>> to deal with these issues, I'm mostly tempted to save on hair by
>> making dnsmasq the default going forward, and write off bind for now.
>> Certainly continue to make it available for advanced users, but
>> install it optionally.
>> The advantages of having something closer to full blown dns in the
>> home are not apparent without tighter integration with dhcp, dhcpv6,
>> ahcp, etc, than presently exists anywhere.
>> Dave Täht
>> http://www.bufferbloat.net/projects/cerowrt/wiki - "3.3.8-17 is out
>> with fq_codel!"
>> Cerowrt-devel mailing list
>> Cerowrt-devel at lists.bufferbloat.net
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