resolv.conf ??

Peter Larsen plarsen at famlarsen.homelinux.com
Thu Aug 9 18:52:15 UTC 2012


On Sun, Aug 05, 2012 at 08:19:19PM -0400, Jim wrote:
> F17
> 
> How do I LOCK-IN namserver ijn resolv.conf so it cannot be changed by 
> Fedora ?

You need to be a bit more specific. "Fedora" doesn't do anything, a particular package does.
For DHCP client connections (controlled/managed by dhclient) it is ORDERED by the dhcp server
to configure the client in a certain way. That includes nameserver etc.  You can override that
with the dhclient.conf file - where you can specify to ignore certain "orders" or you can tell it 
to add constant definitions you want added in all cases. For instance, you may want to use
your local caching nameserver instead of the one your dhcp server tells you to do - you would do
that by adding "option domain-name-servers <ip addr for your local server>" to the dhclient file
under the correct lease section. It's quite more complex that that - check out the dhclient.conf 
man file and the /usr/share/docs/dhclient*/ sample files.

If you instead use static IP setup, then dhclient is not going to be used. And your /etc/resolv.conf
and other changes that dhclient makes, will not take place. But now you have to do a static
setup either in NetworkManager or the old way in /etc/sysconfig/network-scripts (system-config-network).

Things tends to also go bad if you have multiple networks configured. Ie. your laptop has a
wired network connection and a wireless connection. Both connect using dhcp and if not configured
right, they are two different dhcp servers. In that case, who-ever gets the IP LAST wins when it comes
to /etc/resolv.conf. The solution to this is to either use the same dhcp server (tell the wireless
router to turn off it's dhcp server and don't use it as a router) or you need to use dhclient.conf
and specifically tell it, not to modify /etc/resolv.conf for one of the interfaces. And as you can
figure that means if you only connect the one interface that you're telling it to ignore, well, things
won't really work. For that reason I try to never use multiple interfaces where dhclient is active.

I hope this helps. The simple way is to not use dhcp - but that puts the ownership on you to configure
dns, ip, masks, routing, ntp etc. 

Regards
  Peter Larsen



More information about the users mailing list