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

[Daniel Pittman]

Rich Shepard <rshepard at appl-ecosys.com> writes:

> I need help from you folks administering Ubuntu systems. On my wife's laptop
> only the wireless connections are seen (here and in the neighborhood). The
> topmost portion, wired networks, says there aren't any although I have an
> ethernet cable connecting the box to the local router.
>
> I tried running NetworkManager and was told it's already running. Next, I
> tried 'lfconfig -a' and saw eth0 as well as lo and wlan0. When I ran 'ifup
> eth0' I saw 'Ignoring unknown interface eth0=eth0' which makes no sense to
> me.

The "eth0=eth0" part is because Debian[1] support mappings in their basic
network configuration, and in this case you are using the identity mapping
rather than "eth0=home" or whatever.  (Which is no surprise, because you have
not configured that magic. :)

Anyway, it means the interface is not configured in /etc/network/interfaces,
basically, though it wouldn't hurt to check the content there just in case.

(Er, just to check, you /did/ run that command as root, right?)

> What do I do to have the NetworkManager see the wired connection when a cat5
> cable is plugged in and all that interface to be used instead of the wirelss
> one?

Typically nothing.  So, the question is why it isn't working:

What logs does NetworkManager emit?  You should find them in /var/log/syslog
or /var/log/daemon.log, and it would be good to have all the NM output when
you plug and unplug the cable.


Can your NIC actually see the connection?  The cheap way to check would be:

  sudo apt-get install ethtool
  sudo ethtool eth0

...with the cable plugged in, and see what it says.

        Daniel

Footnotes: 
[1]  ...so, eventually, that means also your variant of Ubuntu.

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✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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