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TCP-group 1994


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Re: TCP-Group Digest V94 #276



> 
> Date: Sun, 4 Dec 1994 10:18:59 -0800 (PST)
> From: jerry@tr2.com (Jerome Kaidor)
> Subject: Using DNS for .ampr.org addresses
> 
> Richard Chycoski wrote:
> > 
> > And, there a lot of amateurs who have mail routed via the Internet to  
> > non-Amateur Radio hosts with MX records listed for xyz.ampr.org  
> > addresses. If you choose to ignore (or cannot use) the DNS system,  
> > you will certainly have trouble contacting some people. This isn't a  
> > deficiency of Phil's use of ampr.org, it is caused by the assumptions  
> > that you choose to use. '.ampr.org' doesn't mean that a station is  
> > connected to packet radio, it means that it is a destination  
> > adminstered by a ham. This is exactly what DNS is for, and what many  
> > people still do not realise - domain names must *not* be used for  
> > routing purposes, they are delineators of adminstrative control, not  
> > route descriptors.
> 
> **** OK, Richard, given that I have *only* a UUCP connection and a
> TNC connection, how to you propose that I fix it?  I could send *all*
> mail regardless of address, to my UUCP smart host, and when the 
> ``no such address'' comes back, resend it through the tnc, ONLY
> if it's ``.ampr.org''.  Doesn't sound too elegant.

Nothing like putting the "amateur" back into amateur radio :-)

The lesson is: if you don't set up things properly, don't be surprised
when they don't work.

I'd like to know what happens if you send e-mail to me at
ve7jpm@linux.ve7jpm.ampr.org.  Will it get to me, even though you
direct *all* ampr.org mail out your TNC? It's an amateur site. I'd
like to believe what Brian said about "amprnet being flat", but it
isn't. You can not send mail to my amateur address unless you are
within a few tens of km from my station, *or* you use the IP gateways,
and if you do use the gateways, you *do* have DNS access.

So if you send email to me out your TNC, it probably won't get to me
unless everything is properly routed (hah!). But if you send mail
to ve7jpm@linux.ve7jpm.ampr.org over to your smarthost, it *will* get
to me!

If hosts don't register their domain names and MX records
in the ampr.org DNS, then too bad if they can't get e-mail.

Obviously if your UUCP smarthost forwards mail, it must have a
connection to internet or other mail forwarders somewhere down the
line, and it can access the DNS from there.

Example: 

ve7foobar.ampr.org is an amateur site with a landline connection to a
UUCP site, and also a TCP/IP connection to its local net (and perhaps
a router/gateway)

the DNS stuff for the ampr.org nameserver:

ve7foobar	in	a	44.x.y.z
ve7foobar	in	mx	10	ve7foobar	;=44.x.y.z
ve7foobar	in	mx	20	uucpsite.com.	; your UUCP provider

this assumes your UUCP provider has a port on the internet. If it
doesn't, go upstream from this uucp site until you find the site that
MX forwards for your uucp site.

On the UUCP site:

the UUCP site that knows how to reach ve7foobar.ampr.org via UUCP has
to update its mail routing tables. This is dependent on the UUCP
site's mail software (sendmail, smail, etc.)


What happens:

when someone wants to mail to ve7foobar.ampr.org, the mail transfer
agent is supposed to look at the mx record (NOT the IP address!) and
if it exists, it tries to send to the MX record with the lowest
number. So it tries to send to ve7foobar.ampr.org (NOW it looks at the
IP address: 44.x.y.z) If that fails, which it probably will unless
there is a registered gateway, it moves on to the next MX record. It
finds uucpsite.com, and that's connected to the internet, so it sends
it there. uucpsite.com is then responsible for routing the mail to
you, via landline UUCP or even TCP/IP local routing is enabled for
44.x.y.z.


> 
>   Oh, and if we
> use the DNS system literally, there can be hosts on amateur tcp that
> are NOT in the ampr.org domain, right?   Will all the people who are
> running non-.ampr.org hosts on ham tcpip please raise their hands?
> Gee, there's not many.  Fact is, the ham tcp net is not quite the
> same as the Internet.  
> 
> 
>    I suppose I could find a machine on the tcp-ip net that offers DNS
> lookup, and use it for all my mail.  But first, I don't know if there is such
> a beast, and second, my UUCP link is a direct phoneline connection to 
> a professionally-maintained machine, which is up 24 hours a day, and I
> trust it somewhat more than I trust the tcpip net.  Not to mention that
> the UUCP link isn't subject to amateur restrictions.
> 

So fix your mail routing tables to send mail to *locally* reachable
hosts out your TNC, and send everything else out to your smarthost. If
foobar.ampr.org has a properly set DNS entry, your smarthost *will*
find a way to get to it! You can do this without a DNS, by sending to a
smarthost that does, or by knowing *exactly* which hosts are reachable
from the TNC (not very many!), and sending everything to the smarthost.
But don't assume that .ampr.org is reachable through your TNC.

>                              - Jerry

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BogoMIPS Research Labs  --  bogosity research & simulation  --  VE7JPM  -- 
jmorriso@bogomips.ee.ubc.ca ve7jpm@ve7jpm.ampr.org jmorriso@ve7ubc.ampr.org
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