From: bx953@cleveland.Freenet.Edu (David R. Cohen)
Newsgroups: news.newusers.questions
Subject: No longer a Moron Two
Date: 24 Jul 92 14:40:47 GMT
Reply-To: bx953@cleveland.Freenet.Edu (David R. Cohen)
Organization: Case Western Reserve University, Cleveland, OH (USA)


Another best answer:




From: art@wvus.org (Art Nicolaysen)
To: art@wvus.org, bx953@cleveland.freenet.edu


To: bx953@cleveland.Freenet.Edu
Subject: Re: I'm a moron
>Newsgroups: news.newusers.questions
Organization: World Vision U.S.
Cc:

In article <1992Jul23.170325.11619@usenet.ins.cwru.edu> you write:
>
>Well, I'm not really a moron, but I need you to treat me as though I am
for
>the purpose of this question. 
>
>I have been using the net for about 6 months, and have read most of the
>news.***.newuser stuff.  However, I have not seen this question
>answered anywhere.
>
>In VERY simple and BASIC terms, how does the usenet work and 
>how did it come into
>being.  For instance, someone told me that once upon a time, schools sent
>lots of research results to eachother over computer, and some dweebs got
>the great idea of using the downtime to set up e-mail and usenet.  This
>sounds too simple or wrong, but it is the level of detail I need --
simple.
>Can someone tell me how usenet works and how the computers all hook into
>eachother with the same postings around the world, as though I am in 6th
>grade?  
>
>Please e-mail responses.  This info is actually going into an article I am
>writing for non-computer users.
>
>Thanks in advance.
>-- 
>=-=-=-=-=-=-=-=-=-=-= THIS MESSAGE IS FROM  =-=-=-=-=-=-=-=-=-=-=
>|             David R. Cohen or Tracey L. Ridgeway              |
>|                  bx953@cleveland.freenet.edu                  |
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

I'm including a reply to a newuser query that I wrote last year,
that includes two decent book
references on the workings of Usenet.  I highly recommend the Libes
book for information that has for  long time been passed along in
technical papers or via "oral tradition".  Also, I hear  there is a
new book out, "Zen and the art of the Internet", which may give you a
lot of the things you're looking for.

---------------------------cut here----------------------------------


>Newsgroups: news.newusers.questions
Subject: Re: Mail addresses
Keywords: Where in the net am I?

In article <5040@uafhp.uark.edu> bbs00068@uafcseg.uucp (Joel Kolstad)
writes:
>
>
>I've been using Usenet here for about 6 months, and one thing that
>still really baffles me is... HOW DO I GET MAIL TO WORK?  Mail works
>fine if all I want to do is stay of the same system, but once I go
>cross-country, it's a hit-and-miss game of "mail bounce."
 


I'll try to impart a little bit of what I've picked up in the last two
years as a Unix troll and news reader.  Best sources for info are in
the "frequent postings" that should be found in news.announce.newusers;
I also recomend the following books:

        "Using UUCP and Usenet" ,Todino, O'Reilly & Associates
        (you may send mail to nuts@ora.com for detailed descriptions 
        on this & other helpful books, etc, etc)

        "Life with Unix", Don Libes, Hayden publishers
        (publisher info not certain, but this book is 
        an EXCELLENT source of info not easily found; has
        a nice "history of Usenet" section.)

These are good for starters.  Any technical bookstore should be able to
order these for you, ordinary bookstores, too, if you ask nicely.


Disclaimer:

I may not get everything right is what I'm about to say; I don't want
to lead you into gross errors, so take a look at the books, read the
"frequent postings", and pester your local experts for advice and
explanations.


Full bang paths:

News and mail originally got sent between machines via ordinary
modems and phone lines, and the set of programs that make up UUCP
facilitated the transfers.  Back then, you had to specify the path
that you wanted to send files, i.e "mail cit-vax!elroy!ames!freddy"
to send mail to user freddy on system ames.  This method of addressing
is commonly known as "bang-path" addressing ("!" is pronounced "bang").


Mailing via pathalias:

As the number of systems that ran used UUCP grew, the software
incoporated a database of paths to different systems; this is still in
use on a lot of systems, and goes by the name of pathalias.  With an
up-to-date pathalias database on my system, I no longer have to worry
about giving a full bang-path address.  Using the example above, I can
send mail to freddy at ames by entering "mail ames!freddy", and the
mail software will query the pathalias database for the routing info.


Domains and domain addressing:

The newest method for specifying addresses is known as "domain-based"
addressing.  This notation has been adopted from addressing
conventions used on the ARPAnet. (ARPAnet is no longer around, having
been replaced by a collection of interconnected networks known as the
Internet.  For our purposes, we can treat the Internet as one huge
network.)  When you see ARPAnet, JUST THINK INTERNET.  Now back to
discussion of domains.

>understanding is this -- my address is kolstad@cae.wisc.edu.  

In a domain-based address, as you read from right to left, you go from
bigger to smaller domains.  Top-level domains (in U.S.A) include edu,
org, com, mil, gov, and net.  Country abbreviations are valid
top-level domains (i.e. well.sf.ca.us, system well, in SanFrancisco,
etc).  To my knowledge, UUCP is a pseudo-domain used when a system
doesn't have a valid registered domain.

For your address, wisc is a 2nd-level domain, cae is a system within
that domain (3rd level domains are possible), and kolstad is a user
(natch).  The outside world only has to worry about getting mail to the
system given in the 2nd level, which then routes it to the local
system and user.


Mailing via domain names:

Again, using the original example, I now send mail to freddy as
follows: "mail freddy@ames.nasa.gov" (names given domain-fashion don't
always exactly match with names given bang-path fashion).

>When I mail something off, say to bogus@uxa.cso.uiuc.edu, the letter
>works its way up the three until it comes to a node it recognizes --
>edu, in this case -- and then works its way back down through uiuc to
>cso, uxa, and finally to Mr. Bogus, right?

Not quite.  The topmost system in the sender's local domain does a
query of a system that acts as its "nameserver", to find out how to
access the local domain where the message is headed.  The nameserver 
computers contain addressing information that allows two computers 
on the Internet to make a direct, highspeed connection(~1.54Mbits/sec,
compared to 9.6Kbits/sec for the fastest modems).  This may not be the
EXACT way it's done, but you can see the contrast between this and the
UUCP-only method, where the message is passsed on by a number of
intermediate systems.

I have to point out that you don't have to have a physical connection
to the Internet to utilize domain-based addressing.  We are registered
as wciu.edu, have other machines within our local domain, and have
a listing in a nameserver with a MX (mail exchange) record that shows
what Internet-connected system handles our mail.  We connect to this
system with UUCP and a modem, and have access to the world with a
local phone call. (see map below)


            elroy.nasa.gov ==========================
              /     [
             /       [
            /         [
           /           [
          /       csvax.caltech.edu
         /
    wciu.edu

csvax.caltech.edu was our prior connection to the Internet.
 

Mixing addressing modes:

Addresses with both domain names and bang paths in them can be
confusing, both to humans and mail forwarding software.  With real
dumb  forwarders, mixing modes will guarantee misdelivery and
frustration.  A lot of the time you will see a mixed address when 
  a)  the destination isn't a registered domain, 
  b)  the sender doesn't have a decent pathalias database, 
  c)  or a major gateway between networks must be
      traversed (e.g., from the Internet to Bitnet).


>OK, assuming I'm right so far, let me tack on some other questions:
>What in the world do all those !'s in an address mean?  Such as
>ferbie!hobbes@gmuvax2.gmu.edu?  Is the stuff following the ! yet
>address that relates to a tree, except that now we're talking machine
>names instead of addresses?  In other words, would mailing the
>previous address get to the machine gmuvax2, which in turn is
>connected to a bunch of little machines, including hobbes?  Am I
>totally confused or what?

Remember that bang-paths get more specific as you read left to right,
and domain names have smaller scope as you read right to left.
I would (and hope a decent mail forwarder would) read the address
above as:
    "Deliver to system gmuvax2 within domain gmu.edu, thence to
    system ferbie, thence to user hobbes."

How the address is translated depends on whether the domain part or
the bang part is evaluated first.  I don't think the other reading is
very plausible, because you're trying to get to a domain via a system
that doesn't have a domain name.  If  the intention is "deliver to
ferbie, then gmuvax2.gmu.edu, then hobbes", the address should be 
given as "ferbie!gmuvax2!hobbes", without any any domain syntax.

Here's a real-life example of mixed-mode adressing.  It hardly ever 
caused bounced delivery, but I wouldn't recommend you try it.

    My address this year, since we got our domain registered, is:
        art@wciu.edu.
    Last year, because wciu.edu wasn't available, I used
        wciu!art@csvax.caltech.edu.
    Interpreted as:
    "deliver mail to domain csvax.caltech.edu, thence to system wciu,
    thence to user art."

I believe one of the "frequent postings" articles has a detailed 
discussion on how and how not to go about forming addresses.


>Finally, can somebody distinguish between UUCP, Internet, Usenet, and
>Arpanet for me!?  UUCP to me is a Unix-to-Unix copy program, right?
>So people with UUCP addresses are on machines that don't have direct
>connectors to the Inter/Use/Arpa Net and just call up (presumably)
>other machines every now and then to get mail for them, right?

You've got Questions 2 and 3 right.  Just remember ARPAnet is dead and
buried, except for the mention of it in people's .signature files.
As for Question 1, 

    "Usenet is a worldwide network of UNIX computers that run netnews
    software."          
                        Using UUCP and Usenet, p. 106

Usenet consists of both machines that communicate over the Internet, and
those that use strictly UUCP dial-up connections.


>I realize that this is a lot to answer, and I thank anybody who can
>take the time to do it.  Better yet, can anybody recommend a good
>reference on this bewildering subject?
> 
>Thanks in advance to those with the courage to answer! :-)  --> MY <--
>address on this convoluted (?) network is kolstad@cae.wisc.edu.
> 
>  
>                                               ---Joel Kolstad 
>                                              kolstad@cae.wisc.edu

---------------------------cut
here----------------------------------


-----------------------------------------+----------------------------------
  "Always do right.  You will gratify    | Art Nicolaysen    art@wvus.org
   some people, and astonish the rest"   |
                     Mark Twain          | (somewhere in los angeles
county)
-----------------------------------------+----------------------------------
-- 
=-=-=-=-=-=-=-=-=-=-= THIS MESSAGE IS FROM  =-=-=-=-=-=-=-=-=-=-=
|             David R. Cohen or Tracey L. Ridgeway              |
|                  bx953@cleveland.freenet.edu                  |
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=