freebsd stable - Jul 2008 - dhclient and resolv.conf.sav

Hello,

we have been bitten by something that obvoiusly
is a feature, not a bug, but I do not quite understand
the intentions and reasoning behind it.

I have a host with manual interface and resolver configuration
and an additional interface that should get it's IP address
via DHCP. But only it's IP address and netmask, nothing else.

The DHCP server used hands out only IP addresses/netmasks,
no domain-name-servers, domain-name, etc. configured.

Yet, if there happens to exist a /etc/resolv.conf.sav file,
every renewal of the lease by dhclient overwrites the contents
of /etc/resolv.conf with those of resolv.conf.sav.

In my particular case the .sav file contained an internal
nameserver that was used when I initially set up the host
in the lab. This entry was of no use to the server after
it had been deployed in our datacenter.

Can anyone shed some light on the intended mechanism?
Studying the dhclient-script was not too helpful, either.

Thanks,
Patrick
-- 
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On Thu, Jul 10, 2008 at 10:52:35AM +0200, Patrick M. Hausen
wrote:
> Hello,
> 
> we have been bitten by something that obvoiusly
> is a feature, not a bug, but I do not quite understand
> the intentions and reasoning behind it.
> 
> I have a host with manual interface and resolver configuration
> and an additional interface that should get it's IP address
> via DHCP. But only it's IP address and netmask, nothing else.
> 
> The DHCP server used hands out only IP addresses/netmasks,
> no domain-name-servers, domain-name, etc. configured.
> 
> Yet, if there happens to exist a /etc/resolv.conf.sav file,
> every renewal of the lease by dhclient overwrites the contents
> of /etc/resolv.conf with those of resolv.conf.sav.
> 
> In my particular case the .sav file contained an internal
> nameserver that was used when I initially set up the host
> in the lab. This entry was of no use to the server after
> it had been deployed in our datacenter.
> 
> Can anyone shed some light on the intended mechanism?
> Studying the dhclient-script was not too helpful, either.
I suspect the theory is that you can have a static resolv.conf around
that gets installed when there isn't anything else to use.  In practice,
I think it mostly causes problems.  I'm somewhat tempted to remove the
creation of the file and add something like a resolv.conf.default in
it's place.

-- Brooks
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