Ubuntu

Cant connect to wired network without modifyng /etc/network/interfaces

Asked by Pablo Marchant

I've had this problem with Jaunty for some time, and today I figured how to fix it. The network manager applet, when left clicking it said "device not managed" for my wired network.

I found that if I commented the entries of /etc/network/interfaces that contained eth0, wired network shows no longer this behavior. This is my /etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
#auto eth0
#iface eth0 inet dhcp

Is this a bug??

PD, this is what lshw has to say about my ethernet device:

     *-bridge
          description: Ethernet interface
          product: MCP51 Ethernet Controller
          vendor: nVidia Corporation
          physical id: 14
          bus info: pci@0000:00:14.0
          logical name: eth0
          version: a3
          serial: 00:1b:24:bd:4c:ff
          width: 32 bits
          clock: 66MHz
          capabilities: bridge bus_master cap_list ethernet physical
          configuration: broadcast=yes driver=forcedeth driverversion=0.61 ip=192.168.0.100 latency=0 maxlatency=20 mingnt=1 module=forcedeth multicast=yes

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Ufuk (ufukkilicaslan) said : 		#1

I don't know if it is a bug or not, but you have to change the settings of your /etc/network/interfaces file. If you get automatic IP address, which uses DHCP you should change the lines like this:

# The primary network interface
#auto eth0
#iface eth0 inet dhcp

--to:

# The primary network interface
auto eth0
iface eth0 inet dhcp

--It means delete the "#"s to use your eth0 device, "#" means commenting out these lines, so they won't affect your configuration. You should delete them. And restart you networking:

sudo /etc/init.d/networking restart

--this will enables your etho device and you get an automatic ip, connect to internet.

If you want to manually configure your network as static IP instead of dhcp (usually you use dhcp as in the first case), I can explain this, too.

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Pablo Marchant (pamarca) said : 		#2

Well, the thing is, DHCP didnt worked with the default interfaces file:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

This file gave me the "device not managed" message. Instead, if my interfaces file looks like this:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
#auto eth0
#iface eth0 inet dhcp

 the wired network with dhcp worked...

Revision history for this message
Ufuk (ufukkilicaslan) said : 		#3

Seems like your net connection works independently from /etc/network/interfaces file, so I am not sure about how it is working. I think it uses network-admin settings (nm-system-settings) to work. So your dhcp works without odifiying the file, what exactly is your problem? Could you please define precisely?

Revision history for this message
Pablo Marchant (pamarca) said : 		#4

My problem is that with the default /etc/network/interfaces file, the wired connection doesnt work, and when left clicking the notification icon for the network, below wired network it says "device not managed".

After commenting the lines with eth0 in /etc/network/interfaces, wired network works as it should, just plugging in the cable makes the computer ask for an IP and I get connected.

Revision history for this message
Ufuk (ufukkilicaslan) said : 		#5

So, keep the lines commented. Does it change with every reboot?

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