Q I'm using an E220 USB HSDPA modem under Fedora 9, all working with the new Network Manager 0.7.x. I have a little wireless connection showing up on the task bar and got a IP address. When I right-click on the icon and go to Connection Settings, it keeps showing up 4.2.2.3 and 4.2.2.4 for the DNS settings even when I go to /etc/resolve.conf to change them to use the OpenDNS setting. I don't use an Ethernet cable or wireless with this laptop, only the USB modem. All the websites I've seen have told me to change it in Network Manager and the /etc/resolv.conf file, but when I do, it goes back to 4.2.2.3 and 4.2.2.4. How can I change the DNS settings for the PPP connection (mobile broadband) and get them to stick?
A Fedora is obtaining the DNS addresses from your ISP as part of the DHCP negotiation (see the Frequently Asked Questions box on page 110 for more details on DHCP), which also gives your IP address, default route and some other bits and pieces. It is possible to change this by running the network configuration tool at System > Administration > Network, selecting your modem and pressing the Edit button. Leave the setting to 'Automatically obtain IP address settings with:' at DHCP and untick the box to 'Automatically obtain DNS information from provider' Press OK, then go to the DNS tab and specify your addresses manually.
Don't try to edit /etc/resolv. conf, as this is generated each time you bring up a network interface using the settings you just changed. Some other distros allow you to specify the options used when requesting information from the ISP with either dhcpcd or pump, two common DHCP programs. In such cases, the option to be passed to dhcpcd is -R, which tells it not to rewrite /etc/resolv.conf; pump uses --no-resolvconf to do the same thing.