[sllug-members]: DHCP & DNS Issues

[Stuart Jansen]

On Fri, 2006-06-16 at 18:47 -0600, Elijah Newren wrote: 
> For some reason, my sister's laptop (running FC5, if relevant) isn't
> setting the default gateway when using DHCP to determine network
> settings.  I told her the workaround was to manually run e.g.
>   route add default gw 192.168.0.1
> whenever she boots up or restarts her network.  This manual
> intervention is somewhat annoying, and it strikes me as really odd
> that no default gateway is being set.  This was probably caused by
> people at her work doing some modifications to her laptop to give her
> whatever static configuration she needed there, but somewhat
> embarassingly I can't find what would cause this.  This has happened
> with two different DHCP servers and in both cases my laptop (also
> running FC5) has no such problems with the same network.

My guess is that someone has defined a static route or gateway
somewhere. They probably would have used system-config-network to do it,
so I'd start by poking around there.

Fedora stores it's network settings in two places. The global
file /etc/sysconfig/network
and /etc/sysconfig/network-scripts/ifcfg-<DEVICE>. If there's any static
per-device routes they'll be
in /etc/sysconfig/network-scripts/route-<DEVICE>. I seem to remember a
global static routes file, but not its name.

Less likely, but also possible I suppose, check the contents
of /etc/dhclient*.conf.

Poking through the if* scripts, it looks like you could also have
a /etc/default-route, but I'm betting that is also unlikely.


> Is there any way to configure things to just automatically ignore 
> the bad nameserver and not use it?

Add the line
PEERDNS="no"
to the /etc/sysconfig/network-scripts/ifcfg-<DEVICE> file. Of course,
that ignores all DHCP provided DNS servers.

Alternatively, you can create an /sbin/ifup-local that runs after any
interface comes up. It could them intelligently munge the resolv.conf.
For an idea how to do that,
see /etc/sysconfig/network-scripts/ifup-post.

-- 
Stuart Jansen              e-mail/jabber: sjansen at buscaluz.org
                           google talk:   stuart.jansen at gmail.com

"However beautiful the strategy, you should occasionally look at 
the results." -- Winston Churchill
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
Url : http://sllug.org/pipermail/sllug-members/attachments/20060617/af57970a/attachment.pgp