Ethernet adapter was disable on Ubuntu 17.04

Question

I am using Ubuntu 17.04 but I don't know why my Ethernet interface was disabled.

I tried lshw -C network and it shows this:

WARNING: you should run this program as super-user.
  *-network DISABLED        
       description: Ethernet interface
       product: 82579LM Gigabit Network Connection
       vendor: Intel Corporation
       physical id: 19
       bus info: pci@0000:00:19.0
       logical name: enp0s25
       version: 04
       serial: 00:21:cc:cd:28:8f
       capacity: 1Gbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k firmware=0.13-3 latency=0 link=no multicast=yes port=twisted pair
       resources: irq:28 memory:f2500000-f251ffff memory:f253b000-f253bfff ioport:6080(size=32)

How I can enable it?

Answer 1

Here is how to fix this problem.

Edit file /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf and change it's content from :

[keyfile]
unmanaged-devices=*,except:type:wifi,except:type:wwan

To :

[keyfile]
unmanaged-devices=*,except:type:ethernet,except:type:wifi,except:type:wwan

And then run :

sudo service network-manager restart

That's all.

Answer 2

My Ethernet was also disabled after I upgraded from LTS 16.04 to 16.10 then to 17.04. I was able to resolve by manually doing the following:

sudo ifconfig eth0 up 
sudo dhclient eth0

Answer 3

1. Delete all in /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf

2. Change [ifupdown] managed=false to true in /etc/NetworkManager/NetworkManager.conf

3. restart with sudo service network-manager restart

Answer 4

When I upgraded to 17.04 this network manager file was blocking my system from automatically managing my devices.

/usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf

Content:

[keyfile]

unmanaged-devices=*,except:type:wifi,except:type:wwan

I commented it all out, rebooted, and everything works fine now. It can also be deleted.

Reference: Network Manager refusing to manage wired interfaces

Answer 5

Other's replies solve the problem, but you should not edit the system file /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf since your changes could be overwritten during the next upgrade, and you probably won't remember which is the file involved.

Create a new file instead: /etc/NetworkManager/conf.d/10-globally-managed-devices.conf which overrides the first one. Make it empty or comment its content with the hash symbol:

[keyfile]
# unmanaged-devices=*,except:type:wifi,except:type:wwan

Answer 6

A bit more general answer is sudo lshw -class network, then look for the content after the field logical name, because in my case it was enp5s0, so with this then you proceed to sudo ifconfig enp5s0 up and sudo dhclient enp5s0.