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I'm trying to set up a static IP address for my LTSP server as to configure one of my two NICs (internal one : Server -> Light client) via the /etc/network/interfaces , but when I open the interfaces file all I can see is this :

auto lo
iface lo inet loopback

Is this normal?

user3078046
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2 Answers2

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This is normal. What you have is exactly the same as what's in /etc/network/interfaces on my Ubuntu 14.04 system (which is working fine and networking actively through two separate physical interfaces).

By default an Ubuntu desktop system uses NetworkManager to manage network connections automatically and dynamically. This does not require (and in fact typically requires there not be) entries detailing configuration of your physical interfaces in /etc/network/interfaces.

(NetworkManager, if changed from running in "unnmanaged mode" to "managed mode," will recognize and work with /etc/network/interfaces entries. But unmanaged mode is the default.)

Sources:

Eliah Kagan
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    THank you for the response :) So if I disable Network manager, or change it from running in "unmanaged mode" to "managed mode" I should be able to monitor my network information from the interfaces file, but at the same time still keep the functionalities of network manager? – user3078046 Aug 08 '14 at 11:00
  • According to what I read on the NetworkManager source (on Debian wiki) you provided, if a connexion's information are present on the interfaces file, it is not managed by Network manager, is that the case for Ubuntu 12.04 too? – user3078046 Aug 08 '14 at 11:36
  • @user3078046 Yes, you can change NetworkManager to managed mode and achieve this. Regarding 12.04: I believe yes. That is, I believe unmanaged mode is the default in Ubuntu 12.04 just as it is in later Ubuntu versions like 14.04. However, I don't currently have a 12.04 system on which to check this. You can check this for your system by running `cat /etc/NetworkManager/NetworkManager.conf`. (Or maybe it's `nm-system-settings.conf` in 12.04.) Under `[ifupdown]` is a line, either `managed=true` or `managed=false`. And changing it from `false` to `true` switches from unmanaged to managed mode. – Eliah Kagan Aug 08 '14 at 13:54
  • I did a 'stop' command to disable network manager now I have to start it manually everytime I reboot :S. I went to the NetworkManager.conf to switch [ifupdown] managed=false and turn it to managed=true. I rebooted but it is still disabled on boot, what should I do? – user3078046 Aug 08 '14 at 15:10
  • @user3078046 Do you mean the `NetworkManager` *process* does not run anymore? (If you're not sure, you can check by running `ps ax | grep [N]etworkManager` when you think NetworkManager may not be running.) Or just that it doesn't manage your interface anymore? What "stop" command was run? Did you modify `/etc/network/interfaces` too? If the new issue is that the `NetworkManager` process will no longer run automatically (rather than running but not working the way you want), then you might want to post a separate question about that. (In that case, please include a link here and I'll look.) – Eliah Kagan Aug 08 '14 at 23:23
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No, there should be a lot more info in the interfaces file. Have you tried setting the IP using ifconfig yet?

ifconfig eth0 up
ifconfig eth0 x.x.x.x
ifconfig eth0 netmask x.x.x.x
ifconfig eth0 broadcast x.xx.x.x

or you can try to edit the interfaces file with the following lines:

iface eth0 inet static
    address x.x.x.x
    netmask x.x.x.x
    gateway x.x.x.x
    broadcast x.x.x.x
user300217
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