[arm-allstar] DNS server for HamVoip

[David McGough]

Hi Don,

The new DNS-based node lookup system completely replaces the need for
(repetitive) downloading of the rpt_extnodes file. This solves several
long-standing problems, the two biggest probably being:

... The long latency between when a node registers and when is can finally
connect, due to slow rpt_extnodes file updates. Some users have reported
this latency to be as much as 30 minutes, with typical times I've seen
being 10 to 15 minutes.

... NAT issues with mobile users where IPv4 IP addresses used during UDP
registration may be different from the address used for TCP web access--
which is how the rpt_extnodes file get retrieved.....In this case, the
mobile user will never get a nodelist file and can never connect! Users of 
AT&T 4G service seem to regularly have this problem.

Another benefit of DNS is a huge reduction in wasted Internet bandwidth, 
of course, since no rpt_extnodes files ever need to be downloaded.

To implement these new DNS services, I've setup publicly advertised
secondary DNS servers (as VPS instances) at several major network hubs in
the USA. More will follow.  So far, all the VPS boxes are all running
Ubuntu 16.04 LTS, with the DNS software being bind 9.10.x. Updates
propagate across to these servers via AXFR and IXFR zone transfer methods.

And, I am running fail2ban, of course, to impede entities trying to 
abuse the DNS servers.... *sigh*

Here are answers to some of your questions, below. Please see the answers 
included after your questions:


On Sat, 30 Dec 2017, "Don Backstrom AA7AU via arm-allstar" wrote:

<snip>
> 
> 3) Has your DNS-lookup approach for node IP# now fully replaced the 
> regular repetitive node-list download cycle using the AllStarLink server 
> (which increases bandwidth use and server load over time)?


Yes, the DNS system completely replaces the node-list download.

>
> 4) If so, is there now that savings in initial start-up time as a result 
> compared to the old registration cycle lag?

Yes, from the initial point a node registers, the lookup data is typically 
available via DNS lookup in 30 seconds or less. Ultimately, I expect DNS 
performance to be even faster, perhaps a typical 10 second lag.

>
> 5) Is this bit using the <node#>.asnode.org structure? If not, where is 
> that from? If so, how often is that DDNS updated?

No, we aren't duplicating the functionality provided by asnode.org.  
Rather, I designed a whole new approach from the ground up, implementing a
derivative of the CHAP protocol via DNS. I'll publish in depth details
about how this works, soon. This will include a source code kit for
ACID/DIAL users. I am using crypto methods based on AES, SHA3 and
Argon2. All library code came from heavily scrutinized public-domain (not
GPL) reference sources.

> 
> 6) Can we rely upon the asnode.org setup to remain in place, and usable, 
> from now forward, and therefore not need the use of our own 
> ddclient/DDNS setups for these AllStar node PIs?

I can't say for sure, since we're not the group providing that service.  
But, I see no technical reason why asnode.org can't continue. The
rpt_extnodes files should remain available for download as long as they're
needed.

> 
> 7) Is your new DNS sever logic cache-based or does it lookup every time 
> a remote node# is referenced (like connect, monitor, etc)? If so, could 
> you explain a bit about that?

The dynamically generated DNS records have strategically set time-to-live
(TTL) values, so, entries do remain briefly cached locally for rapid-fire
lookup requests (which app_rpt can generate!). This speeds up DNS access
and further reduces wasted Internet bandwidth.

> 
> 8) <rhetorical> Is there a way to force new users to read the 
> documentation first, or is this, like all system-related stuff, always a 
> repeat of Ground Hog Day? </rhetorical>

Yeah, "reading" is becoming obsolete, particularly when people try to use 
the tiny screens on today's portable devices. Doug & I have already 
discussed some setup videos.


> 
> 	TIA!
> 
> 	Best Wishes for a Happy, Healthy, and Prosperous New Year ...
> and a big *THANK YOU* to you and David for all that you've done.
> 
> 	- Don - AA7AU




Happy New Year!

73, David KB4FXC