TK1 and IP Address Woe

I’m literally tearing what hair I have left out trying to figure out what is going on with the IP address assignment on my TK1 running Ubuntu.

Having Googled the heck out of the problem, I still have no idea where to begin and - although Toradex don’t officially support Ubuntu - I was wondering whether anyone would be able to offer advice.

I want to assign my TK1 a permanent static IP address.

So far, I have disabled network-manager, used the /etc/network/interfaces file and added the following information:

auto eth0
iface eth0 inet static

I have also removed the avahi-autoip package which seems to give a 169.254.X.X address if a DHCP server is not found after a period of time, adding an extra eth0:avahi interface to the ifconfig and ip addr lists.

When I take down and bring back up the eth0 interface, I can see that the static IP address is assigned to the interface - for a short period of time. After that, the IP assignment disappears from the interface and a lot of RTNETLINK answers: Network is unreachable messages appear (which I’m not able to stop).

What I want, is a permanent static IP address assigning to the eth0 interface. Something that never changes, never gets revoked, never removed but ALWAYS works.

Please please please can anyone offer any advice as to what may be going on.

I guess by default Ubuntu 14.04 is using NetworkManager rather than /etc/network/interfaces for configuring eth0 which can be seen by the former being rather empty after a fresh JetPack installation:

ubuntu@tegra-ubuntu:~$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d
ubuntu@tegra-ubuntu:~$ ls -l /etc/network/interfaces.d
total 0

So may I suggest you configuring it through that thingy instead.