Xref: utzoo unix-pc.uucp:217 comp.sys.att:8475 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!david From: david@ms.uky.edu (David Herron -- a slipped disk) Newsgroups: unix-pc.uucp,comp.sys.att Subject: Re: Machine names on the net ... Message-ID: <13689@s.ms.uky.edu> Date: 15 Jan 90 03:32:38 GMT References: <33@suntau.UUCP> <25902@cup.portal.com> Reply-To: david@ms.uky.edu (David Herron -- a slipped disk) Organization: U of Kentucky, Mathematical Sciences Lines: 89 In article <25902@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes: >forrie@suntau.UUCP (Forrie Aldrich) in <33@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 <- ska: David le casse\*' {rutgers,uunet}!ukma!david, david@UKMA.BITNET <- <- New official address: attmail!sparsdev!dsh@attunix.att.com