Is it possible to manually activate an eth0 connection?

NoOp glgxg at
Thu Jan 15 23:47:18 UTC 2009

On 01/15/2009 03:42 AM, Bas Roufs wrote:
> still 'down'. However, I get stuck here, because I simply do not yet
> manage to edit the file "/etc/network/interfaces" - because of
> different reasons.
> Packages like 'emacs' and 'midnight commander' are not yet available,
> because they need to be installed first, for which I need an internet
> connection with the laptop.
> I do manage to open the file "/etc/network/interfaces" via another
> texteditor, Kate, as 'normal user'.

For a Gnome desktop you would use: gksu gedit /etc/network/interfaces
I 'think' that for a KDE desktop you can use:
kdesu kate /etc/network/interfaces

You should then be able to edit in superuser mode.

Regarding your other problem; do you see any interface as up when you
issue the 'ifconfig -a' command from a terminal? An 'up' interface will
look something like this:

~$ ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:0c:f1:ba:25:1f
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::20c:f1ff:feba:251f/64 Scope:Link
          RX packets:254264 errors:0 dropped:0 overruns:0 frame:0
          TX packets:249008 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:170267098 (162.3 MB)  TX bytes:21434370 (20.4 MB)

Don't worry if your's is different - it should be - I'm just showing
this one to you so you'll know what to look for.

Also, if you look at the above, you'll see the HWaddr for the interface.
That is the MAC address. From a terminal:

~$ cat /etc/udev/rules.d/70-persistent-net.rules

and look to see if the MAC address for eth0 is in that file. For example
from mine:

# PCI device 0x8086:0x1050 (e100)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:0c:f1:ba:25:1f",
ATTR{type}=="1", NAME="eth0"

So you see that the address there matches the ifconfig HWaddr output.

My reason for asking is that I experienced a similar problem on an
intrepid test machine recently. Interface address in
/etc/udev/rules.d/70-persistent-net.rules had been swapped to eth1
rather than eth0 & it took me nearly an hour to figure out the problem.
Initially, just to get the machine on the network I used the intrepid
network manager to change the connection to eth1. I then later changed
the /etc/udev/rules.d/70-persistent-net.rules file to reflect the proper
MAC address, rebooted and all is working now.

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