Machine names on the net ...
David Herron -- a slipped disk
david at ms.uky.edu
Mon Jan 15 14:32:38 AEST 1990
In article <25902 at cup.portal.com> thad at cup.portal.com (Thad P Floryan) writes:
>forrie at suntau.UUCP (Forrie Aldrich) in <33 at suntau.UUCP> writes:
> I am confused about names of computers... I have been told that you can
> only have a maximum of 6 characters for a machine name...
...
I'm afraid that there's enough mis-information here that I must step in and
correct what I can.. Generally, Thad, I enjoy reading your postings but
this time you're a bit off the track.
>... I've used PDP-10, Tenex, DEC-20, Foonly (all related) systems
>since their inception (the PDP-10 back around 1965), and one interesting
>aspect of it was that, for "efficiency", filenames were stored in a single
>36-bit machine word allowing up to 6 characters in a filename. My conjecture
>is THIS is the genesis of the 6-character machine name. ^^^^^^^^^^
Good thing you labeled this as conjecture.. I fail to see how a
strangeness on a non-Unix OS could affect naming of machines in a
network of what amounts to being Unix BBS's. I know TOPS-10 quite well
(incidently, they fit 6 characters into 36 bits by using a restricted
character set that fit into 6 bits/character. tricks like this are
easy on the PDP-6/10/20 architecture since it allows for varying byte
sizes)
>The Usenet, as such, started circa 1980 (if memory serves), and was required
>to be in conformance with Arpa protocols (e.g. email formats, and so forth,
>based on what's known as RFC 822).
Yes, 1980. But, RFC-822 wasn't written until a couple years later.
Also the earlier versions of Usenet -- remember that we're on the B
version of Usenet right now, earlier version was A -- used a very
different header format. And again within the B version there was
a number of changes in format over time. Earlier versions of B had
(conscious?) incompatibilities with RFC-822, for instance Article-ID:
instead of Message-ID:.
The compatibility with RFC-822 came in around the time of B v2.11
and RFC-950.
>For whatever reason(s), all the early protocols permitted up to 6-char names,
>and much extant uucp software still abides those restrictions. More
>recently, HDB (aka BNU) (circa 1984) uucp software permits up to 8-character
>names. I "believe" it's possible names can be longer (your "snorklewacker",
>for instance :-) but they must be UNIQUE within the first 6 (or 8)
>characters.
There's a couple places where a limit can come from:
-- Usenet software & what it can put into the sys file, and Path: lines.
I wouldn't be surprised if early versions of Usenet software had a
limit on this name. I'd also be surprised if there were *still* a
limit. There isn't any intrinsic limit since the format is "name!name!..."
Note that the name for Usenet purposes is (can be) different from your
UUCP or domain names. Especially since a Path: line looks so much like
a UUCP route-address that people insist on believing that it contains
useful information for routing e-mail. It is best if you use the same
name everywhere... but the software doesn't require this.
-- UUCP software has had a variety of limits on host names. Usually in
the range of 6-8 characters. There's no really good reason for this
other than early development was done on PDP-11's and the software from
that era shows all sorts of strange limits supposedly to make the software
*fit* in the first place.
Funny, this 3b1 I'm on right now seems rather small (memory wise) --
especially when I think about porting X to it.
-- Arpanet names. I don't believe there was ever a limit, except for
what people were willing to type. In fact, there were numerous
machine names which were rather long when I started in on the nets
in '84 .. a whole bunch of 'em at CMU with names like
cmu-cs-foo-baz.arpa
Then the naming pattern for gateway machines is to name the connected
networks and tack "gw" on the end. Like uky-sura-gw.uky.edu.
There was some interaction between arpanet hosts and Usenet hosts in the
early days of Usenet. In fact, my first lesson on the uselessness of
Path: lines as e-mail addresses was while I was trying to use Path:
lines to get UUCP routing information. I learned real quick that the
machine named "vgr" wouldn't pass any UUCP mail through it, despite what
it said in the Path: line.(vgr.arpa is now == vgr.brl.mil)
--
<- David Herron; an MMDF guy <david at ms.uky.edu>
<- ska: David le casse\*' {rutgers,uunet}!ukma!david, david at UKMA.BITNET
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