How To Implement the OpenVPN Data Channel Offload on Linux

An OpenVPN Engineer Presents at NetDev

NetDev 0x16 was held from October 24 to 28, 2022 in Lisbon, Portugal. This technical conference on Linux networking is a conference “of the netdev community, by the netdev community, for the netdev community,” as stated on their website. The event is entirely focused on Linux kernel networking and user space utilization of the interfaces to the Linux kernel networking subsystem. 

Antonio Quartulli, a Principal Engineer at OpenVPN, was featured during the conference with his presentation, “Pushing OpenVPN Down the Stack: Data Channel Offload (DCO).” 

“During the presentation, I touched on various technical points of DCO,” says Quartulli, “and I managed to collect important feedback about things that can be done better — or about things we should also add in future releases.” Quartulli has been developing a new Linux kernel module for the past year and a half, the goal of which is to boost the performance of OpenVPN on Linux. 

“The most exciting part is that OpenVPN performance gets boosted big time thanks to this new DCO kernel module.”

Antonio Quartulli, OpenVPN Principal Engineer

While Quartulli is working on this project alone, the end goal is to get the DCO integrated into the main Linux kernel codebase. “When that happens, any person running Linux will automatically get our code,” says Quartulli. But the integration process is a long one. “You need to present your code to the kernel community, have it reviewed, possibly make changes following the received feedback, and then eventually, it will finally land in the codebase.” Part of the integration process for Quartulli, in fact, was this conference, which was recommended for him in order to present his work to a broader audience. “The integration process is still ongoing,” he explains, “and I plan to send another integration request soon.”

Quartulli’s presentation, like the conference itself, was a hybrid event, with both in-person and remote attendees. “The event was very nice because it was not a big conference or trade show, but was very technical — the audience was mostly other Linux kernel developers,” says Quartulli. With such a focused audience in attendance, presenters were free to get as technical as necessary, which made for some fascinating exchanges. “Most of the presentations were about ongoing developments in the Linux kernel space, what’s coming next, and cutting-edge software, with a focus on super high performance networking.”

For any kernel developers curious about how Quartulli is implementing DCO, his presentation is a must-watch. See the whole session here: 

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