From: lyndon@unbc.edu (Lyndon Nerenberg)
Newsgroups: can.uucp
Subject: Re: NEW MAPS POSTED (AND REPO
Date: 2 Oct 92 16:28:41 GMT
Organization: University of Northern B.C.

pacolley@ember.UUCP (Paul Colley) writes:

> There's one other reason:  If he registers his name in the maps,
> there will be less problems with misdirected mail.  If he doesn't
> take the UUCP name, sooner or later somebody will...

> Trust me.  There are a large number of sites that apparently can't
> tell the difference between "ember.uucp" and "ember.some.domain.name".

Registering ember under .uucp will just make that problem get worse.
You wouldn't believe how many sites send mail for canada.their.domain
to my machine now that it's a "registered" uucp site. My worst offender is
AT&T.

There are two factors that contribute to this problem. The first involves
laziness on the part of the person sending the mail. Rather than using
foo@canada.att.com they shorten it to foo@canada, and assume their mailer
will add the ".att.com" for them. The second problem involves a badly
configured gateway mailer that gives precedence to canada.uucp over
canada.att.com.

If you stick to using *real* registered domain names (NOT foo.uucp) this
is never a problem.

There is *never* a need to register a uucp map entry if you are a leaf site.
The only time you require a uucp map entry is when you are providing uucp
transport forwarding of mail to third-party sites (uunet for example).

For example, let's say I register ampr.bc.ca as my domain. My machine name
is canada. My internet forwarder is unbc.edu, aka unbc in the uucp maps.
In my domain registration I list my internet forwarder as unbc.edu, and
my uucp forwarder as unbc. This results in the following information being
published in the uucp map entry for the ampr.bc.ca domain:

unbc.edu	ampr.bc.ca(DIRECT), .ampr.bc.ca(DIRECT)
unbc		ampr.bc.ca(DIRECT), .ampr.bc.ca(DIRECT)

When you run pathalias against this it will generate a uucp route like this:

ampr.bc.ca	...!unbc!ampr.bc.ca!%s

If you set things up this way, nobody has to know what your uucp nodename
is (except your forwarder). If your uucp name changes, nobody has to
know except your forwarder. This is as it should be. On the internet, we
use the DNS and domain names as labels for machines that use IP addresses
at the transport layer. If an IP address changes, nobody cares since that's
hidden y the domain name. There is no reason why the same philosophy cannot
be applied to the uucp transport as well.

There is another reason to avoid using uucp names instead of domain names.
There is no guarantee that your uucp name won't be duplicated in the maps.
It has happened before, and it will happen again. And there is nothing
stopping me from publishing a map entry for my system that lists a route
to your machine, even though the ember I'm talking about is an interal
machine, not yours. This exact scenario happened in Edmonton several
months back. A machine within the U of Alberta Electrical Engineering
dep't listed a DEDICATED connection to one if it's internal machines. The
name of that machine duplicated the name of a registered uucp site in
Europe. Suddenly all of western Canada's email for Europe was routing
through this little box on the fifth floor of the EE building that in
fact talked to nobody. If everyone used registered domains this would
never happen.

--lyndon