31 Aug 2008

Ubuntu Network manager, static interface setup, multiple profiles, no internet, no dns

Recently I decided to experiment with the multiple profiles feature of the network manager provide by Ubuntu 8.04. I set up my lan network card with a static ip address so that I could manager port forwarding on my router specifically for my laptop.

I still wanted to be able to switch to the roaming mode provided by the network manager if I went to university or some where else. So I decide to save the set up in the network manager as a separate profile. I then saved other profile for the roaming modes on my wireless lan, and my cable lan interfaces.

After a restart I found that I could no longer get out on the internet after start up. I was not sure what the problem was. I could ping my router but nothing beyond my router. In checking my network manager set up I could see that where I used to have my router as a dns, I now had nothing.

So I add some dns servers saved the settings under my static profile and applied these setting buy clicking the green tick. Now every thing was working again. I could connect to the internet web pages would now load in firefox.

Again after a restart I found I had the same problem so I check my network manger and found that the settings were still there but were not applied. So I again choose the correct profile and applied the settings. This behaviour of being not being set up after a restart continued. It gets a little irritating having to go into network manager and apply setting after ever restart.

After reading around in fourums I found about about resov.conf resolvconf /etc/resolv.conf, /etc/resolvconf/interface-order and /etc/resolvconf/resolv.conf.d/. I could see that in interface-order and ifconfig my cabled lan card was begin configured correctly at start. In the resolv.conf file no dns servers were configured at start up, having no dns server to resolve requests out to the internet I could not browse the web or send emails or any thing you would need to do.

To solve the problem of not being set up at start up open the /etc/resolveconf/resolv.conf.d/base as root in a text editor and add a dns server like your router or some other dns server. Read the man resolvconf to find out why. Redundancy here is a good thing, have it point to more then one dns server.

Simply place entries like "nameserver" or "nameserver #your router#". Obviously is localhost and probably wont work for the average set up. If your not sure what dns servers to use, ping a top level domain like www.com or www.co.za and get their ip address. Do a traceroute and look for domain names with .dns in them. You can see and example of how network manager saves one of these file in /etc/resolvconf/resolv.conf.d/original.

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