Satish Balay wrote:
On Thu, 8 Apr 2004, Keven Ring wrote:
Exactly whats required for laptops :) - with one more step
DHCP Client: I'll make my own DNS entry in /etc/hosts for mmm.nnn.ooo
Satish
Wow. In a nutshell, you have reduced this whole thread to: In some
way, shape, or form, get the hostname that you want your machine to be
in either DNS or /etc/hosts. As others have pointed out [myself
included], this is not even needed if you set your hostname to something
other than "localhost", "localhost.localdomain", or "(none)". There are
GUIs for doing this, and there are the files that the GUIs edit.
As I indicated earlier, if your ip address is really changing and you
want your hostname to remain the same, then you should consider having a
dynamic DNS. If your ip address and hostname changes, then all you need
is DNS [assuming there is a one-to-one between ip and hostname].
/etc/hosts is fine for static stuff. Keep dynamic stuff out of it.
I was merely highlighting the intriguing [and somewhat useless]
conversation that could occur between the DHCP client and server. Now,
having said that, I'd say it's a great design - there are 50 ways of
doing the same thing, each of them with their own uses and benefits. It
just means that it appears silly to ask the DHCP server for a hostname
when you know you are going to ignore it...
I must say I was just adding to the 'intriguing' protocol you had -
another important step - which is also required for the non-localhost
approach :) - but I do use the non-localhost approach - and the
suggestion is well taken.
And I must admit the problem I'm solving is slightly different than
the one that initated this thread.
Problem specification: x/xauth is screwed up. When hostname changes -
the current authentication is broken (and you can no longer open
xterms etc..)
As a simple demonstation for this problem - do (as root):
hostname
xterm
hostname foobar
xterm
- solution 1: don't let DHCP-client change the hostname [which is
where most of the discussions of this thread is dealing with]
a: (recommended) use non-localhost hostname - and have an entry
for it in /etc/hosts for DNS
b: if the hostname gets changed by dhcp-client - change it back
using 'hostname' command. This gets annoying with
short-lease-dhcp servers.
c: the alternate intriguing protocol - just for fun :)
- solution 2: fix 'xauth/some-other-script' some-other-way so that
'if the hostname changes' then the appropriate xauth for this new
'hostname' is added automatically. I managed to this manually once,
but don't remember the command anymore. But this approach has a
potential to preserve ip addresses/names.
The problem is that xdm creates the initial cookie based on the
hostname. All additional auth sessions base off that cookie. If you
change the hostname, then the initial cookie is no longer valid.
I think the command you used was "xauth generate :0 ."
This issue will continue to be a problem as long as DHCP servers don't
heed the client's requested host name as many don't. Even if they don't
do DDNS, they can still return the requested host name to the client.
Sure, the host won't be visible to the internet under its FQDN, but the
vast majority of DHCP environments do NATing anyway, so it's kind of a
moot point.
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- Rick Stevens, Senior Systems Engineer rstevens@xxxxxxxxxxxxxxx -
- VitalStream, Inc. http://www.vitalstream.com -
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