OpenVPN Data Channel Offload (aka OVPN-DCO)

Intro

The expression Data Channel Offload refers to any technique implemented with the goal of moving the processing of data packets from the userspace program to a separate entity.

Given that OpenVPN spends a considerable amount of time passing data packets back and forth from kernel-land to user-land, where decryption and re-routing happens, it was decided to offload the data processing directly to the kernel. As direct consequence, data packets are not required to leave the kernelspace anymore, thus boosting the performance of ongoing VPN connections.