[arm-allstar] Hairpin NAT

[Doug Crompton]

​Here is an email I got from Bryan describing in a little more detail about
the local address resolution in a LAN. Obviously if you have a router that
can handle the public address resolution back to itself locally (hairpin
nat) it should work for you but I believe this would still require that you
have your servers on different iax ports which you should anyhow.​

---------- Forwarded message ----------
From: Bryan D. Boyle <bdboyle at bdboyle.com>
Date: Wed, Feb 22, 2017 at 10:00 PM
Subject: Hairpin NAT
To: wa3dsp at gmail.com


There is a function that is beginning to appear, due to the prevalence of
NAT'd addresses in most locations, such as that implemented by the Ubiquity
routers called "Hairpin NAT".  Probably others, but this is what I'm most
familiar with.

Basically, what it does is that if during DNS resolution the address
returned is the outside address of the router (such as I have here at the
home QTH, where the FiOS modem is in bridge mode, and my router is
resolving the nailed IP address), the resolved address given to my internal
systems (and port) for the host name is the internal IP address.  In the 2
years I've had the Ubiquity router online, it has worked flawlessly, which
cuts down the number of distinct configurations...such that my IAXRPT
points to www.wb0yle.com whether I'm inside or outside of my boundary and
connects just fine.

Tested with test nodes such as my 1999 right now which, inside, has my
local hubnode specified as 27673=radio at www.wboyle.com/27673,NONE on the
same network subnet...and has no problem connecting.

I know that most people would go "hmmmmm", but figured you'd get it. Has
made the configuration of a lot of things (RemoteRig for my HF work,
IAXRPT, internal web spaces (I run 8 web sites for non-profits as well as
my own sites, down right now due to a system crash, but will be back as
soon as I can get to microcenter and pick up some refurb desktops and
SSDs...) etc. a lot less complex.

Just putting this out there for whatever.

THanks for all the work you've done with your fork of allstar.  With the
loss of Jim, active interests in continuing the project are appreciated.
Good work on 1.5...has a lot of interesting and leading-edge features that
I can't wait (the press of a Real Job has kept me running) to dive into.

73 Bryan WB0YLE/W2FUV trustee