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After upgrading two instances of an older Ubuntu (10.10 and 11.04) to 12.04, I notice an apparent conflict between the way my network interfaces were previously managed and the new methodology, which apprently is extremely "Network-Manager-Centric."

It seems that my previous configurations, stored in /etc/network/interfaces, continue to work, but tools like 'dhclient' not longer function as expected. Now, in order to re-configure the interface between a static IP and a DHCP IP, I've discovered the best solution is to comment out all but the 'lo' adapter in the /etc/network/interfaces file, and just perform all my configuraion changes with Network Manager.

My question is 2-fold:

  1. Is this expected behavior, as part of some kind of long-term plan to exclusively use Network Manager?
  2. Is there documentation which describes the current state of network interface management in Ubuntu?
share|improve this question

You can disable the networkmanager, take a look at this link.

But why does dhclient not work (or is not working as expected)? Have you altered the dhclient.conf?

dhclient <NIC> "should" almost always work.

share|improve this answer
Previously, 'dhclient eth0' ALWAYS worked. Now, it produces the message 'RTNETLINK answers: File exists' and the old static settings remain. As far as I can tell, I'm not the only one who's encountered this: – Avian00 May 28 '13 at 13:50
Send in a bug report. It should work. – Anders May 28 '13 at 19:43

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