*BSD News Article 98738


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From: brian@shift.lan.awfulhak.org (Brian Somers)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Hostname for box w/ part time internet connection
Date: Mon, 30 Jun 1997 02:59:18 +0100
Organization: Awfulhak Ltd.
Message-ID: <mt37p5.vq1.ln@shift.lan.awfulhak.org>
References: <24a9fb8b.u9t27e.14589@slip106.termserv.siu.edu>
Reply-To: brian@awfulhak.org, brian@utell.co.uk
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In article <24a9fb8b.u9t27e.14589@slip106.termserv.siu.edu>,
	jimd@slip106.termserv.siu.edu (Jim Dutton) writes:
> Hi Brian, on Jun 28 you wrote:
> 
>> In article <33B462A3.C9A68B9C@auburn.campus.mci.net>,
>>       Anthony Jenkins <ajenkins@auburn.campus.mci.net> writes:
>> > What do I set as the host name for my machine, which occasionally
>> > dials-up a connection to the internet?  Do I use the domain name of=
> =20my
>> > ISP, or would that be naughty?  I have a single PC running FreeBSD
>> > (Win95 on another partition), no network (though I soon hope to del=
> ve
>> > into the wonderful, hair-pulling world of small network admin. when=
> =20I
>> > get another box), and dial-up PPP access to the internet.
>>=20
>> localhost.my.domain ?  Alternatively, pick a name that's not
>> likely to be real (ending with say .lan) and give it an IP
>> number that's not real (say 10.0.0.1).
>>=20
>> > Thanks in advance,
>> > Anthony
>>=20
>> --=20
>> Brian <brian@awfulhak.org> <brian@freebsd.org>
>>       <http://www.awfulhak.org>
> 
> 
> Brian - I am surprised at this lame-brain suggestion (just pick a name)=
> =2E
> No WONDER there are so many BOGUS hosts on the Internet!

Eh ?  Now you've got me started :)

<RANT>
If the truth's to be known, IMO, a machine name is bogus to start
with.  If I have a machine with N network interfaces, then by
definition, I have N names.  So what makes any one of these names
better than the other ?

To prove this, set up the following network (not uncommon):

              --------------
 'NET--------| 158.152.17.1 |    -
             |              |    |
             |     10.0.1.1 |----|
              --------------     |
                                 |
                                LAN
                                 |
                                 |     --------------
                                 |----| 10.0.1.4     |
                                 |     --------------
                                 -

Bearing in mind that 10.0.1.1 isn't any sort of router for
anything (10.0.1.4 *doesn't* want to be 'net connected, or
has some other gateway).

Now, run some sort of application that believes in host
names (X is the worst example!).  I try to start a client
on 10.0.1.4, and X in its infinite wisdom sends the "hostname",
and *not* the name on the interface it's connecting on
(ie 10.0.1.1).

10.0.1.4 has no idea what a 158.152.17.1 is !
</RANT>

> We had a student on our campus who likewise thought that such a naming
> convention was acceptable, until he just happened to choose a name that
> was registered to another organization in B.C, Canada (and we are in
> Illinois).

<RANT>
So what ?  Any problems resulting are IMO software bugs.
Of course in the above example, 10.0.1.4 shouldn't really
be allowed to do things like send mail and post to usenet -
there's no way for that machine to create correct From:
lines or to create unique message ids.  This is circumvented
(in my case) by hacking sendmail full of things like
MASQUERADE_AS, and setting "reply-to" addresses in usenet.

A good example is this message.  It's posted from that 10.0.1.4
machine (ok, in practice, 10.0.1.1 *is* a gateway!).  I've called
my LAN "lan.awfulhak.org" because I own "awfulhak.org" and know
that "lan.awfulhak.org" isn't registered - this sorts out the
"uniqueness" of my message ids.  The From: line is bogus though,
so if people don't use the reply-to: line, they get bounces.
This is probably why I get very little spam (cheshire cat type
cheesy *grin*).
</RANT>

> Anthony - take a look at the MANual page for PPPD. It should have some
> information on setting up an "IP-UP" script for use with PPP which you
> SHOULD USE to properly set your hostname and IP address to what is
> determined during the PPP negotiation. I can post a sample script later
> (with IFCONFIG, and HOSTNAME commands) if need be.

I hope this doesn't involve changing your "hostname" while running.
This gets tricky.  You've got to at least HUP sendmail (assuming it's
being run with a full path name), and you must restart things like
rwhod & (old versions of) nmbd and any other brainos that use hostname.

Hmmm, I must fix rwhod.

> 
> =20      ///  A M   M I GGGGG A      Senior Sys Prog - Network Admin
> =20     ///  AA MM|MM I G     AA     Southern Illinois University, USA
> \\\  ///  A A M M M I G GGG A A                              =20
> =20\\\///  AAAA M   M I G   G AAAA   jimd at dutton2.it.siu.edu        =
> =20=20
> =20 \///  A   A M   M I GGGGG A   A  jimd at slip106.termserv.siu.edu
> 
> _______________________________________________________________________=
> _
> SIU.EDU          - DNS Admin, Postmaster, SMTP Admin, Netnews Admin
> SIUCVMB.SIU.EDU  - DNS Admin, Postmaster, SMTP Admin, TCP/IP Sys Prog
> SIUCMVSA.SIU.EDU - DNS Admin, Postmaster, SMTP Admin, Sr TCP/IP Sys Pro=
> g
> SIUCVMB, SIUCMVSA- Senior RSCS, VTAM, NCP Systems Programmer
> Systems Admin    - 2.0 Suns, 0.4 IBM RS/6000's, 2 FreeBSD, 1 NetBSD
> Behemoth Admin   - Suzuki Cavalcade
> 

-- 
Brian <brian@awfulhak.org> <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour !