Help - 'resolv.conf' being overwritten on startup with DNS from my old VPN settings

MonkeyMagic23 · 01-11-2009, 02:22 PM

I took me a while to get this far. After setting up VPNC at home to connect to my University network I found that I could only access the internet when the VPN was connected.

Eventually worked out it was a DNS server problem.

The Uni DNS server was at the top of the list in my 'resolv.conf' file. I have now removed the VPNC package and the config files for my Uni connection. I can manually edit the 'resolv.conf' file to remove that DNS server. This works as long as the computer is left on, but every time I restart my computer the Uni DNS server is written back into my 'resolv.conf' file.

I am using a wired network with 'Automatic (DHCP)'. I know another option would be to turn off DHCP and set my DNS manually, but ideally would like the flexibility of DHCP and I can't see why the University DNS would be added by DHCP.

Someone help me....

repo · 01-11-2009, 03:06 PM

as root edit
/etc/dhcp3/dhclient.conf

Edit the following two lines to read as

supersede domain-name “mydomain.com”;
prepend domain-name-servers 192.168.1.1

MonkeyMagic23 · 01-11-2009, 07:24 PM

Thanks for the quick response. OK. I have followed half your instructions.

I have added to my /etc/dhcp3/dhclient.conf file the line -
prepend domain-name-servers 192.168.1.1;

I did not add -
supersede domain-name “mydomain.com”;
for three reasons. I dont understand what it is supposed to do, I am not sure what to put in place of “mydomain.com”, and my reading suggests that the prepend change alone should fix the problem.

It has not. My unwanted server 130.209.4.16 is still at the top of the list after a manual edit of my resolv.conf file then a reboot.

What now?

anomie · 01-11-2009, 08:27 PM

I'll likely get flamed for saying this, but you could edit /etc/resolv.conf (and set it up the way you want it) and then - if you're using an ext2/3 filesystem - run:

# chattr +i /etc/resolv.conf

The file will be immutable, and nothing will be changing it, period. That's the big hammer approach until you're able to put together a proper fix.

MonkeyMagic23 · 01-18-2009, 09:05 AM

Got this advice over on ubuntuforums.otg -

"check the /etc/resolvconf/run/interfaces/ directory for the vpn interface and delete it. so if your vpn interface was on "tun0" then you need to delete the "tun0" file(s)."

The tun0 file did contain the offending DNS and deleting it has fixed the problem.

Not sure what will happen when I try to install VPN again though...