PPP

PPP (Point-to-Point Protocol) is commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption, and compression.

Installation
Portage has a USE flag  for enabling support for PPP for other packages.

After setting global USE flags update your system to the changes take effect:

Or emerge package manually:

Kernel
Following kernel options need to be enabled, to support PPPoE, which is used in most cases.

Finally you need to rebuild linux, install and boot new kernel with PPP support.

Configuration
Provided eth0 following lines should be added for PPPoE connection:

Create an init script for the PPP device by symlinking to net.lo: