How to execute an object file: Part 2
April 02, 2021 11:00 AM
Continue learning how to import and execute code from an object file. This time we will investigate ELF relocations....
How to execute an object file: Part 1
March 02, 2021 12:00 PM
Ever wondered if it is possible to execute an object file without linking? Or use any object file as a library? Follow along to learn how to decompose an object file and import code from it along the way....
A quirk in the SUNBURST DGA algorithm
December 18, 2020 12:30 AM
On Wednesday, December 16, the RedDrip Team from QiAnXin Technology released their discoveries (tweet, github) regarding the random subdomains associated with the SUNBURST malware which was present in the SolarWinds Orion compromise. I...
ASICs at the Edge
November 27, 2020 1:00 PM
At Cloudflare, we pride ourselves in our global network that spans more than 200 cities in over 100 countries. To accelerate all that traffic through our network, there are multiple technologies at play. So let’s have a look at one of the cornerstones that makes all of this work....
Diving into /proc/[pid]/mem
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....
MORE POSTS
September 15, 2020 11:00 AM
Secondary DNS - Deep Dive
The goal of Cloudflare operated Secondary DNS is to allow our customers with custom DNS solutions, be it on-premise or some other DNS provider, to be able to take advantage of Cloudflare's DNS performance and more recently, through Secondary Override, our proxying and security ca...
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September 09, 2020 11:00 AM
Unimog - Cloudflare’s edge load balancer
Unimog is the Layer 4 Load Balancer for Cloudflare’s edge data centers. This post explains the problems it solves and how it works....
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July 08, 2020 11:00 AM
Sandboxing in Linux with zero lines of code
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....
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June 18, 2020 11:56 AM
Why is there a "V" in SIGSEGV Segmentation Fault?
My program received a SIGSEGV signal and crashed with "Segmentation Fault" message. Where does the "V" come from? Did I read it wrong? Was there a "Segmentation *V*ault?"? Or did Linux authors make a mistake? Shouldn't the signal be named SIGSEGF? ...
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May 06, 2020 11:00 AM
Cloudflare Bot Management: machine learning and more
This is the ongoing story of Bot Management at Cloudflare and also an introduction to a series of blog posts about the detection mechanisms powering it...
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March 05, 2020 1:00 PM
The History of the URL
On the 11th of January 1982 twenty-two computer scientists met to discuss an issue with ‘computer mail’ (now known as email). Attendees included the guy who would create Sun Microsystems, the guy who made Zork, the NTP guy, and the guy who convinced the government to pay for Unix...
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March 02, 2020 1:00 PM
When Bloom filters don't bloom
Last month finally I had an opportunity to use Bloom filters. I became fascinated with the promise of this data structure, but I quickly realized it had some drawbacks. This blog post is the tale of my brief love affair with Bloom filters....
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December 05, 2019 7:28 AM
Thinking about color
An exploration of building accessible color systems for flexible UI theming. ...
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November 29, 2019 8:00 AM
A History of HTML Parsing at Cloudflare: Part 2
The second blog post in the series on HTML rewriters picks up the story in 2017 after the launch of the Cloudflare edge compute platform Cloudflare Workers. It became clear that the developers using workers wanted the same HTML rewriting capabilities that we used internally, ...
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September 27, 2019 1:01 PM
Workers Sites: Extending the Workers platform with our own serverless building blocks
As of today, with the Wrangler CLI, you can now deploy entire websites directly to Cloudflare Workers and Workers KV. ...
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September 25, 2019 1:00 PM
The Technical Challenges of Building Cloudflare WARP
If you have seen [our other post] you know that we released WARP to the last members of our waiting list today. With WARP our goal was to secure and improve the connection between your mobile devices and the Internet. ...
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September 24, 2019 1:01 PM
Inside the Web Browser’s Performance API
Building a beautiful, feature-rich website is easier than ever before. Not long ago, you’d have to fire up a text editor and hand-craft a lot of HTML, CSS, and JavaScript. Today, you can use WYSIWYG tools and third-party libraries that make development much simpler....
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July 12, 2019 3:45 PM
Details of the Cloudflare outage on July 2, 2019
Almost nine years ago, Cloudflare was a tiny company and I was a customer not an employee. Cloudflare had launched a month earlier and one day alerting told me that my little site, jgc.org, didn’t seem to have working DNS any more. ...
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July 10, 2019 1:07 PM
A gentle introduction to Linux Kernel fuzzing
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....
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