Bug 551962 - dhclient -6 overwrites /etc/resolv.conf set up by NetworkManager
Summary: dhclient -6 overwrites /etc/resolv.conf set up by NetworkManager
Alias: None
Product: Fedora
Classification: Fedora
Component: dhcp
Version: 15
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Jiri Popelka
QA Contact: Fedora Extras Quality Assurance
Depends On: 668153
Blocks: 654642
TreeView+ depends on / blocked
Reported: 2010-01-03 11:38 UTC by Frank Crawford
Modified: 2013-02-08 15:47 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
: 654642 (view as bug list)
Last Closed: 2011-09-30 14:54:37 UTC
Type: ---

Attachments (Terms of Use)

Description Frank Crawford 2010-01-03 11:38:46 UTC
Description of problem:

dhclient -6 (DHCP client for DHCPv6) overwrites setting in /etc/resolv.conf made by NetworkManager.

Version-Release number of selected component (if applicable):

How reproducible:
100% of time.

Steps to Reproduce:
1. Connect to a network with NetworkManager supporting IPv4 and IPv6.
2. Invoke /sbin/dhclient -6 to obtain IPv6 not obtained by NetworkManager.
Actual results:
Observe that in /etc/resolv.conf, the original information supplied by NetworkManager has been replaced by dhclient IPv6 information.  In particular all IPv4 addresses in nameserver lines have been replaced by IPv6 addresses.

Expected results:
Both IPv4 and IPv6 addresses should be available in /etc/resolv.conf.

Additional info:
This configuration is brought about by the fact that NetworkManager does not support the full RA option set, and in particular the "AdvManagedFlag on" setting.

Comment 1 Jiri Popelka 2010-04-12 14:11:08 UTC
Maybe interesting thread:

Comment 2 udo 2010-09-14 14:56:05 UTC
Currently I am hacking dhclient-script etc for ipv6 PD support etc, so I might take a look at this problem as well. See https://bugzilla.redhat.com/show_bug.cgi?id=626514 for the pd/radvd stuff.

Comment 3 udo 2010-09-14 15:18:33 UTC
Question: assuming we have the dns info from the dhcp server, plus also the local stuff that goes in resolv.conf, how would I combine that? I mean, in what order, what way?

# start local part
search bla.local
domain bla.local
# end local
# start dhcp part
search isp.com
server x.y.z.a
# end dhcp part


Comment 4 Bug Zapper 2011-06-02 17:00:46 UTC
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Comment 5 Jiri Popelka 2011-09-30 14:54:37 UTC
The solution to this problems would be in having a middleman which takes the nameserver information from each service (dhclient, NetworkManager, initscripts etc.) and merges them together to form one resolv.conf. The openresolv (bug #668153) program addresses this.

However this BZ has been quite invalid since NetworkManager supports IPv4 & IPv6 including responding to RA O & M bits (so there are actually no reasons now to run another dhclient because of IPv6).

It could also cause more pain (see bug #668153, comment #3 + bug #679445, comment #2) than gain (udo is the only person I know about who would benefit from this).

Closing as wontfix.

Comment 6 udo 2011-09-30 15:04:11 UTC
So what is the solution for this issue for PD users?
Prefix Delegation is the proper way to roll out IPv6.
So why ignore that market?

And why is NM doing whatever you describe? It doesn't even handle the most basic stuff, so why entrust it with stuff that belongs to another program?
NM does udev, does dhclient, what is next?

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