[PLUG] Xubuntu-10.4: Network Manager Does Not See Wired Network

Dale Snell ddsnell at frontier.com
Mon Oct 25 18:48:30 UTC 2010


On Mon, 25 Oct 2010 10:57:18 +1100
Daniel Pittman <daniel at rimspace.net> wrote:

> > The trouble seems to be that if you have NetworkManager set
> > to accept both IPv4 and IPv6 connections, it _requires_ both
> > to be running, or it won't see the interface.  If your router
> > is IPv4 only (as mine is) then the IPv6 connection is never
> > made, and the interface never comes up.
> 
> Er, NM only establishes network *addresses*, and will never
> accept a network connection with any protocol from anywhere.
> 
> Additionally, IPv6 will automatically configure a link-local
> network address in the absence of any infrastructure, so unless
> you disable IPv6 in your kernel entirely you would have an
> address found regardless of what your router supports.
> 
> 
> Now, you might have problems with other applications - that do
> make network connections - if IPv6 is enabled, but that is not
> much to do with NM itself.

Well, actually...  I seem to have described the problem I had
incorrectly.  My mistake, sorry. :-(  NM wanted to configure both
IPv4 and IPv6 networks for the interface.  When it couldn't, it
threw up its metaphorical hands in despair.  

I reported this (without knowing the cause) to Red Hat's Bugzilla
(<https://bugzilla.redhat.com/show_bug.cgi?id=569024> if you're
interested).  Here's what they told me (the first line is a
quote from my log file):

> comment #4:
> Apr 14 11:12:17 localhost NetworkManager: <info> (eth0): IP6
> addrconf timed out or failed.
> 
> Your connection has probably IPv6 method set to "Automatic".
> That's why NM tries to configure IPv6, but it times out (your
> network is probably not IPv6-enabled).  So NM marks the
> connection as invalid even if IPv4 succeeded.
> 
> I think it could be regarded as a bug. We may just issue a
> warning that IPv6 is not available and continue with IPv4 only.
> 
> To resolve the issue, open nm-connection-editor:
> 1. click on "System eth0" connection on "Wired" tab
> 2. click "Edit..."
> 3. click "IPv6 Settings" tab
> 4. change Method from "Automatic" to "Ignore"
> 5. click Apply
> 

I followed the directions, and voila! it worked.  I haven't had
any trouble with it since.  I will say that I don't use NM on my
desktop anymore; dhclient seems quite sufficient.  My laptop
still uses it, though, and it seems to work fine.  (Knock wood...)

Now that I think about it, it's quite likely that I managed to
disable IPv6 when I first set the laptop up.  I have some vague
recollection of something like that.  It's been a while, though.

--Dale

--
"Bring on the lightning!  We'll build a monster for fun!
Bring on the lightning!  We'll turn him loose when we're done!
It's very frightening -- See how the villagers run!
Pull that switch and catch the lightning -- Before the storm is
done!"  -- from "Girl Genius," sung to the tune of Beer Barrel Polka



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