Date: Sun, 7 Nov 2004 11:26:02 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Lloyd Hayes <lloyd545220-trucker@yahoo.com> Cc: freebsd-questions@freebsd.org Subject: Re: Naming confusion Message-ID: <20041107112602.GA22451@happy-idiot-talk.infracaninophile.co.uk> In-Reply-To: <418DC569.2060106@yahoo.com> References: <418A53E5.40404@yahoo.com> <44mzxu6g00.fsf@be-well.ilk.org> <418DC569.2060106@yahoo.com>
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On Sat, Nov 06, 2004 at 11:49:13PM -0700, Lloyd Hayes wrote:
[ Hostname changes when going on-line from different locations ]=20
> >don't worry about it.
>=20
> With XFree86, it is an issue.
> It appears that Xorg won't configure correctly without it. Although I=20
> won't swear that's the problem with Xorg.
One problem you will run into, with either flavour of X Windows, is to
do with the authentication mechanism. X is designed to be network
transparent -- so I can run an X program somewhere else on the net and
have it put its windows etc. on my local desktop. See xauth(1) for a
program you can use to manage access in that way. The problem is that
the records xauth(1) keeps in ~/.Xauthority are based on the machine's
hostname -- and that includes connecting to the local desktop too, as
a degenerate case of 'across the network'. So if your hostname
changes, suddenly you may well have to quit your current X session,
log out and log in again to reestablish those credentials.
There are other programs, like sendmail(8), ipfw(8), natd(8), which
will tend to have an adverse reaction to the hostname and IP number
changing out from beneath them unless very carefully configured.
Now, usually this doesn't pose too much of a problem as typically
dhclient(8) isn't configured to modify the hostname. The trouble
happens when the authentication system tries to *verify* the host
name. It does that by looking up the name in the DNS, which returns
one or more IP numbers. Then it looks up those IP numbers, and counts
the name as verified if any of them return the original hostname.
[Well, there's a bit more to it than that involving various other DNS
record types, but that's the basic idea]
You can see that there are going to be problems with this if you're
moving between different connectivity providers:
* Either you choose your own hostname and stick with it -- except
that the IP number you get from the ISP won't resolve back to
that hostname. In this case you could use a 'dynamic dns' type
service, as provided by eg. http://www.dyndns.org/ -- not
recommending that serive in particular, just using it as an
example. However this is normally used by home users and
precise timings of updates etc. may make it unsuitable for you.
You'll have to experiment.
Note that the hostname doesn't actually *have* to correspond to
any of the IP numbers configured on any of the interfaces, but
that most software will assume that it does unless configured
otherwise. And it can be quite tricky to configure some
packages to cope with that sort of setup.
* You accept the hostname that goes with the IP number dished out
by the ISP temporarily. That means logging out and back in
again when you go on-line. =20
=20
> I've been using my backup computer as a test bed for the various=20
> operating systems. M$ has never been real reliable. But my virus=20
> software seems to be blocking viruses almost daily which are aimed at=20
> one Microsoft product or another. It has become apparent to me that any=
=20
> computer that I have which is connected to the Internet needs to be=20
> using non-M$ products. I had hoped to make a painless transfer to one of=
=20
> the Linux or BSD products, much as I did about 11 years ago when I=20
> jumped from CBM and Apple computers to PCs. (13 years of using CBM=20
> computers and only a couple of years of using Apples.)
Have you considered using a MacOS X machine? It has all of the
reliability and power of a Unix box, together with a user interface
which has had tens of thousands of man-hours put into polishing away
all of those sort of usability problems. It's very different indeed
from the old MacOS.
In theory you can configure a FreeBSD portable to be almost as
flexible configuration-wise as a MacOS box is. But it isn't as easy,
and it certainly isn't for complete beginners. As you say, in so many
words: FreeBSD demands that you learn. Once you've got over the
initial hump most people find it quite rewarding and a very pleasant
OS to use.
> So far, it has been anything but painless. The priorities of a UNIX=20
> system is far different then what I've experienced. And I have yet to=20
> get a UNIX type system developed enough to access the Internet. One=20
> challenge or another keeps cropping up.
>=20
> So, it seems that I'm hitting text books again, and asking questions=20
> during my spare time....
>=20
> The question that I keep asking myself is if I can get to a point with=20
> FreeBSD, or any UNIX type system, where I am comfortable with it and I=20
> can make it adapt to my changing environment. At this point, I feel that=
=20
> if I can learn enough about it, FreeBSD is my best answer. My reasoning=
=20
> is that while newer programs are always put into usage on any OS, you=20
> can usually still manually configure everything with FreeBSD.
Yes. When people say that FreeBSD is a 'server OS', one of the things
that they imply is that it will be configured with a permanent network
connection, unchanging hostname and all the rest. That's FreeBSD's
natural environment and where it is easiest to deal with. =20
What you want to do is -- I wouldn't say unnatural -- but certainly
less usual. Consequently there's less experience of people building
that sort of configuration, less documentation, more bugs, more things
that are perhaps a bit awkwardly conceived. While books will cover
much of what you need, chances are they're missing odd crucial little
nuggets here and there. Usually such hints can be found on the web --
in blog pages or bits of HTML that people have put up documenting how
they did something. Read it with a judicial eye, as often it will
make odd unwarranted assumptions about exactly what software you're
using or exactly what you're trying to do. It's the raw
documentation, if you like, that the more polished works like the
Handbook are distilled out of.
> Since many of the processes running on FreeBSD require a 'named'=20
> computer, I need to know how to handle this. Otherwise, as it says in=20
> "The Complete FreeBSD" book, there will be processes which will not run,=
=20
> or else they will not run correctly on my computer. The answer to this=20
> problem does not seemed to be addressed while using 'dhclient' in any of=
=20
> the printed information that I could find.
Actually, there isn't "an" answer to this problem. There's a whole
series of answers dealing with separate bits of software that may or
may not be running on your system. That means you can use a divide
and conquer strategy, but as we so often say around here "show us the
details". Apart from anything else, that should let us identify
exactly which piece of software is causing that specific problematic
effect.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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