NetworkManager

NetworkManager is a network management software for Ethernet, Wifi, DSL, dialup, VPN, WiMAX and mobile broadband network connections.

Prerequisites
NetworkManager uses udev, D-Bus and polkit, so set them up first.

NetworkManager uses the plugdev group, so add your user to plugdev.

Kernel
You need to disable the following kernel options:

For Wifi devices enable also the following options:

Software
Portage knows the global USE flag networkmanager for enabling support for NetworkManager in other packages. Enabling this USE flag will pull in automatically:

The USE flags of networkmanager are:

After setting this you want to update your system so the changes take effect:

Also install a frontend:
 * - GNOME frontend
 * - KDE frontend
 * nmcli (part of networkmanager) - command line frontend

There are also some extensions:
 * - VPN connection to a OpenConnect server
 * - VPN connection to a OpenSwan server
 * - VPN connection to a OpenVPN server
 * - VPN connection to a PPTP server
 * - VPN connection to a SSTP server
 * - VPN connection to a Cisco VPN concentrator

Boot service
You can now start NetworkManager:

To start NetworkManager at boot time, add it your default runlevel:

Reload D-Bus so that the NetworkManager changes take effect:

nm-applet and X session startup
To be able to get nm-applet started when starting your light X session or light desktop environment, just put the following line in your file:

For support, add the following lines before the previous line. This will ease password management for GnuPG, ssh and Wifi:

Troubleshotting

 * GNOME bugtracker: known bugs
 * GNOME Wiki
 * GNOME Wiki