How to fix Wired Network interface “Device not managed” error in Debian or Kali Linux?

How to fix “Device not managed” error

As of Debian 6.0 “Squeeze”, (or in Kali Linux which is based on Debian) Network Manager does not manage any interface defined in/etc/network/interfaces by default.

Unmanaged devices means Network Manager doesn’t handle those network devices.

So this is what you see in GUI

 An ifconfig -a show you this:

 

This occurs when two conditions are met:

The file /etc/network/interfaces contains anything about the interface, even:

allow-hotplug eth0
iface eth0 inet dhcp

And /etc/NetworkManager/NetworkManager.conf contains:

[main]

plugins=ifupdown,keyfile

[ifupdown]
managed=false

Screenshot below:

Enabling Interface Management

If you want Network Manager to handle interfaces that are enabled in /etc/network/interfaces:

Set managed=true in /etc/NetworkManager/NetworkManager.conf. So this file looks like:

[main]
plugins=ifupdown,keyfile

[ifupdown]
managed=true

Restart Network Manager

Issue the following command to restart network-manager.

service network-manager restart

Now Network Manager should come up with a connected interface. For wired, eth0 with DHCP will show you something like the following image:

Just to wrap it up, lets do another ifconifg -a from command line

Some explanations

“Auto Ethernet” and “Auto eth0”

Auto Ethernet means “Select an Ethernet interface automatically”

Auto eth0 means “autoconfigure the eth0 interface”.