dhcp evils

Michael Hennebry hennebry at web.cs.ndsu.nodak.edu
Tue Apr 19 23:37:16 UTC 2005


On Tue, 19 Apr 2005, William Hooper wrote:
> Michael Hennebry wrote:
> > On Mon, 18 Apr 2005, William Hooper wrote:
> >
> >> Michael Hennebry wrote:

> >>> None of these seem like likely prospects.
> >>>
> >>
> >> dhclient-eth0.leases screams relevant to me.
> >
> > I had thought so to until someone told me that
> > dhcp didn't provide hostnames.
>
> They are mistaken.
>
> > Here it is:
> [snip]
> > option host-name "stmike";
> [snip]
> > Is this telling me that the client told the server that
> > the client's name is stmike, that the server told the client that the
> > client's name is stmike, or something else?
>
> According to man dhclient, the dhclient.leases file stores information
> received from the dhcpd server.

Now I think I know what is going on.  Please correct any mistakes.
At some point, my dhclient told Cable One's dhcp server that I
wanted the hostname "stmike".
The name "stmike" is being stored by the server and sent
to me whenever dhclient does its thing, e.g. at boot time.

Here is what I think is supposed to be happening at reboot.
dhclient acquires an IP address, but not a hostname.
Someone does a DNS lookup on the IP address and uses
the result for the hostname.
Again, please correct any mistakes.

What I think caused the difference:
An accidentally deleted dhclient.conf file.
According to its man page, host-name is among the default requests.
My troubles began after rebooting to get rid of a hung process
that I could not kill.
The reboot sequence required that I run fsck.
My suspicion is that dhclient.conf got deleted in the mess.
Would someone tell me whether an FC3 installation running
dhclient normally has a non-empty dhclient.conf?

The cure would be to provide a useful dhclient.conf,
remove dhclient-eth0.leases, and reboot.
The result should be a new lease that does not include a hostname.
Is there a way to tell the server to forget the name "stmike"?
If for some reason dhclient asks for a hostname again,
I'd like that name to be gone.

-- 
Mike   hennebry at web.cs.ndsu.NoDak.edu
"I AM DEATH, NOT TAXES.  *I* ONLY TURN UP ONCE."  --  Death




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