/etc/network/interfaces did not contain any configuration for Ethernet on a Lenovo Z50 70 after installing 14.04.2 LTS Server from CD

[RayH]

I did a clean install on a Lenovo Z50 70 with an erased hard disk from the Server install CD version 14.04.2 LTS.

lsb_release -rd
Ubuntu 14.04.2 LTS

The install succeeded without warnings. Packages were downloaded from online.

After reboot the system came up normally to a command prompt, but there were no working network. connections.

The r8169 Ethernet driver had loaded normally and there was nothing strange in dmesg.

Further debugging via lshw -c network showed that only the loppback interface was configured and the other interfaces were marked *-network DISABLED.

Checking /etc/network/interfaces indeed showed that there was no configuration for the relevant devices.

workaround:

Manually edited /etc/network/interfaces and added the following lines

auto p2p1
ifacce p2p1 inet dhcp

reboot, and all was nominal.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: debian-installer (not installed)
ProcVersionSignature: Ubuntu 3.16.0-30.40~14.04.1-generic 3.16.7-ckt3
Uname: Linux 3.16.0-30-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.8
Architecture: amd64
CurrentDesktop: GNOME
Date: Wed Mar 25 16:18:30 2015
InstallationDate: Installed on 2015-03-25 (0 days ago)
InstallationMedia: Ubuntu-Server 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
MachineType: LENOVO 20354
MemoryUsage:
 total used free shared buffers cached
 Mem: 8066212 1741260 6324952 148772 69172 1108088
 -/+ buffers/cache: 564000 7502212
 Swap: 8278012 0 8278012
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.16.0-30-generic.efi.signed root=/dev/mapper/hostname--vg-root ro
SourcePackage: debian-installer
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/20/2014
dmi.bios.vendor: LENOVO
dmi.bios.version: 9BCN29WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: Lancer 5A5
dmi.board.vendor: LENOVO
dmi.board.version: 31900058WIN
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo Z50-70
dmi.modalias: dmi:bvnLENOVO:bvr9BCN29WW:bd10/20/2014:svnLENOVO:pn20354:pvrLenovoZ50-70:rvnLENOVO:rnLancer5A5:rvr31900058WIN:cvnLENOVO:ct10:cvrLenovoZ50-70:
dmi.product.name: 20354
dmi.product.version: Lenovo Z50-70
dmi.sys.vendor: LENOVO