[unclug] Linux DNS/DHCP question....

Jeff Bollinger jeff01 at email.unc.edu
Fri Jan 9 17:07:36 EST 2004


On Fri, 9 Jan 2004, Joel Dunn wrote:

> Guys & Gals, every now and then I get to take off my manager hat and put
> on a techie hat, even if it's in support of my own personal LAN at
> home.  My user community (i.e. family) can be demanding customers.
>
> I've got a Toshiba server appliance  (SG10), which runs RH6.1, as my
> internet gateway.  Been using this for 18 months and it's very nifty and
> *much* better than a basic SOHO router :-).  Sometimes I use it's
> web-based config interface, and sometimes I do things the "old
> fashioned" way.  However, I don't get technical often enough and the
> management stuff crowds out the technical bits in my brain.
>
> Here's the scoop.  Roadrunner changed their DNS servers this week (in
> the early morning of the 7th).  I've got my gateway set up for DHCP so
> when RR changes things (i.e. IP address) that works fine, although they
> don't do that often -- I've had the same IP address for over a year.
> However, when they changed DNS, my system didn't adjust things.  After
> some mental fumbling, I remembered /etc/resolv.conf, and changed the DNS
> servers (got the #'s from a neighbor with a Linksys which *did* pick up
> the change).  Things still didn't work until I finally remembered (last
> night) that I was running a caching named, and after I changed
> /etc/named.conf and restarted named, things were hunky-dory again.
>
> So....my question is, Oh Linux Gurus, should my system have noticed the
> DNS change *without* an IP address change/lease expiration?  Why do the
> Linksys-type boxes pick up those changes?
>
> An ancillary question...in the back of my mind, I remember that UNC now
> does not allow DNS references from the outside world, right, due to
> attacks last summer?  So I can't use the UNC DNS facilities...right?
>


Joel, good to see you on this list!  Have you checked out the
'allow-update' option under the 'zone' directive in named.conf?  I believe
it will allow automatic
DNS updates from a specified server.  Not the most secure method I'd
imagine (given the possibility of DNS posioning), but it may do the trick
that the Linksys boxes do.

I know that UNC blocks 152.2.21.1, but I'm not 100% sure we're blocking
152.2.253.100. If you're using the VPN though, you shouldn't have any
problems.  I believe when connected through the VPN your DNS settings
automatically get set to UNC's...

Jeff





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