IPv6

April 28, 2026

Shutdowns, power outages, and conflict: a review of Q1 2026 Internet disruptions

The first quarter of 2026 saw a surge in Internet disruptions, from nationwide shutdowns in Uganda and Iran to unprecedented drone strikes on cloud infrastructure. We explore the data behind these events using Cloudflare Radar.

November 7, 2025

DIY BYOIP: a new way to Bring Your Own IP prefixes to Cloudflare

Announcing a new self-serve API for Bring Your Own IP (BYOIP), giving customers unprecedented control and flexibility to onboard, manage, and use their own IP prefixes with Cloudflare's services.

October 21, 2025

A deep dive into BPF LPM trie performance and optimization

This post explores the performance of BPF LPM tries, a critical data structure used for IP matching.

March 20, 2025

Simplify allowlist management and lock down origin access with Cloudflare Aegis

Cloudflare Aegis provides dedicated egress IPs for Zero Trust origin access strategies, now supporting BYOIP and customer-facing configurability, with observability of Aegis IP utilization soon.

February 8, 2024

connect() - why are you so slow?

This is our story of what we learned about the connect() implementation for TCP in Linux. Both its strong and weak points. How connect() latency changes under pressure, and how to open connection so that the syscall latency is deterministic and time-bound

December 14, 2023

Using DNS to estimate the worldwide state of IPv6 adoption

In the last decade, IPv6 adoption on the client side went from under 1% to somewhere in the high 30 to low 40 percent, depending on whos reporting, but theres also the other end of the equation: the server side

September 26, 2023

Amazons $2bn IPv4 tax and how you can avoid paying it

In this blog, well explain a little bit more about the technology involved, but most importantly, give you a step-by-step walkthrough of how Cloudflare can help you eliminate the need to pay Amazon for something that they shouldnt be charging you for in the first place

February 2, 2023

Cloudflare's handling of a bug in interpreting IPv4-mapped IPv6 addresses

Recently, a vulnerability was reported to our bug bounty about a bug in the way some of our code interprets IPv4 addresses mapped into IPv6 addresses.

March 4, 2019

Building fast interpreters in Rust

In the previous post we described the Firewall Rules architecture and how the different components are integrated together. We created a configurable Rust library for writing and executing Wireshark-like filters in different parts of our stack written in Go, Lua, C, C++ and JavaScript Workers.

September 10, 2018

Fixing an old hack - why we are bumping the IPv6 MTU

Back in 2015 we deployed ECMP routing - Equal Cost Multi Path - within our datacenters. This technology allowed us to spread traffic heading to a single IP address across multiple physical servers.

August 16, 2018

Enable Private DNS with 1.1.1.1 on Android 9 Pie

Android 9 Pie includes a slew of new features around digital well-being and privacy. Here's how to use the new Private DNS feature with 1.1.1.1.

July 19, 2018

IPv6 in China

At the end of 2017, Xinhua reported that there will be 200 Million IPv6 users inside Mainland China by the end of this year.. Halfway into the year, were seeing a rapid growth in IPv6 users and traffic originating from Mainland China.

March 29, 2018

eBPF, Sockets, Hop Distance and manually writing eBPF assembly

A friend gave me an interesting task: extract IP TTL values from TCP connections established by a userspace program. This seemingly simple task quickly exploded into an epic Linux system programming hack.

December 21, 2017

2018 and the Internet: our predictions

At the end of 2016, I wrote a blog post with seven predictions for 2017. Lets start by reviewing how I did. Ill score myself with two points for being correct, one point for mostly right and zero for wrong. Thatll give me a maximum possible score of fourteen. Here goes...

May 25, 2017

Less Is More - Why The IPv6 Switch Is Missing

At Cloudflare we believe in being good to the Internet and good to our customers. By moving on from the legacy world of IPv4-only to the modern-day world where IPv4 and IPv6 are treated equally, we believe we are doing exactly that.

November 21, 2016

98.01% of sites on Cloudflare now use IPv6

It's 2016 and almost every site using Cloudflare (more than 4 million of them) is using IPv6. Cloudflare sees significant IPv6 traffic globally where networks have enabled IPv6 to the consumer.

June 7, 2016

Supporting the transition to IPv6-only networking services for iOS

Early last month Apple announced that all apps submitted to the Apple Store June 1 forward would need to support IPv6-only networking as they transition to IPv6-only network services in iOS 9.

September 28, 2015

Happy 5th Birthday, CloudFlare!

Today is September 27, 2015. It's a rare Super Blood Moon. And it's also CloudFlare's birthday. CloudFlare launched 5 years ago today. It was a Monday. While Michelle, Lee, and I had high expectations, we would never have imagined what's happened since then.