October 27, 2020 12:00 PM
A few months ago, after reading about Cloudflare doubling its intern class, I quickly dusted off my CV and applied for an internship. Long story short: now, a couple of months later, I found myself staring at Linux kernel code and adding a pretty cool feature to gVisor....
September 18, 2020 11:00 AM
SYN-cookies help mitigating SYN-floods for TCP, but how can we protect services from similar attacks that use UDP? We designed an algorithm and a library to fill this gap, and it’s open source!...
July 08, 2020 11:00 AM
In this post we will review Linux seccomp and learn how to sandbox any (even a proprietary) application without writing a single line of code....
April 06, 2020 11:00 AM
We were wondering - can we just enable Linux "conntrack"? How does it actually work? I volunteered to help the team understand the dark corners of the Linux's "conntrack" stateful firewall subsystem....
March 25, 2020 12:00 PM
Encrypting data at rest is vital for Cloudflare with more than 200 data centres across the world. In this post, we will investigate the performance of disk encryption on Linux and explain how we made it at least two times faster for ourselves and our customers!...
March 18, 2020 12:00 PM
Back when Cloudflare was created, over 10 years ago now, the dominant HTTP server used to power websites was Apache httpd. However, we decided to build our infrastructure using the then relatively new NGINX server....
October 12, 2019 1:00 PM
We recently gave a presentation on Programming socket lookup with BPF at the Linux Plumbers Conference 2019 in Lisbon, Portugal. This blog post is a recap of the problem statement and proposed solution we presented....
July 18, 2019 2:12 PM
Securing access to your APT repositories is critical. At Cloudflare, like in most organizations, we used a legacy VPN to lock down who could reach our internal software repositories. However, a network perimeter model lacks a number of features that we consider critical to a team...
July 10, 2019 1:07 PM
For some time I’ve wanted to play with coverage-guided fuzzing. I decided to have a go at the Linux Kernel netlink machinery. It's a good target: it's an obscure part of kernel, and it's relatively easy to automatically craft valid messages....
May 30, 2019 1:00 PM
Kali Linux turned six years old this year! In this time, Kali has established itself as the de-facto standard open source penetration testing platform....
May 18, 2019 3:00 PM
Recently at I gave a short talk titled "Linux at Cloudflare". The talk ended up being mostly about BPF. It seems, no matter the question - BPF is the answer. Here is a transcript of a slightly adjusted version of that talk....
May 03, 2019 1:00 PM
It is unlikely we can tell you anything new about the extended Berkeley Packet Filter, eBPF for short, if you've read all the great man pages, docs, guides, and some of our blogs out there. But we can tell you a war story, who doesn't like those? ...
April 24, 2019 6:21 PM
Our servers process a lot of network packets, be it legitimate traffic or large denial of service attacks. To do so efficiently, we’ve embraced eXpress Data Path (XDP), a Linux kernel technology that provides a high performance mechanism for low level packet processing....
January 04, 2019 11:02 AM
The Linux AIO is designed for, well, Asynchronous disk IO! Disk files are not the same thing as network sockets! Is it even possible to use the Linux AIO API with network sockets in the first place? The answer turns out to be a strong YES! ...
November 29, 2018 9:54 AM
As TLS 1.3 was ratified earlier this year, I was recollecting how we got started with it here at Cloudflare. We made the decision to be early adopters of TLS 1.3 a little over two years ago. It was a very important decision, and we took it very seriously....
August 24, 2018 3:11 PM
Here at Cloudflare we use Prometheus to collect operational metrics. We run it on hundreds of servers and ingest millions of metrics per second to get insight into our network and provide the best possible service to our customers....
May 13, 2018 4:00 PM
How an innocent OS upgrade triggered a cascade of issues and forced us into tracing Linux networking internals....
April 17, 2018 10:11 PM
In previous blog post we discussed how we use the TPROXY iptables module to power Cloudflare Spectrum. With TPROXY we solved a major technical issue on the server side, and we thought we might find another use for it on the client side of our product....
April 12, 2018 1:00 PM
Introducing Spectrum: a new Cloudflare feature that brings DDoS protection, load balancing, and content acceleration to any TCP-based protocol.Today we are releasing Spectrum. ...
