Photo by Niko Soikkeli / Unsplash

The root of the DNS tree has been using DNSSEC to protect the zone content since 2010. DNSSEC is simply a mechanism to provide cryptographic signatures alongside DNS records that can be validated, i.e. prove the answer is correct and has not been tampered with. To learn more about why DNSSEC is important, you can read our earlier blog post.

Today, the root zone is signed with a 2048 bit RSA “Trust Anchor” key. This key is used to sign further keys and is used to establish the Chain of trust that exists in the public DNS at the moment.

With access to this root Trust Anchor, it would be possible to re-sign the DNS tree and tamper with the content of DNS records on any domain, implementing a man-in-the-middle DNS attack… without causing recursors and resolvers to consider the data invalid.

As explained in this blog the key is very well protected with eye scanners and fingerprint readers and fire-breathing dragons patrolling the gate (okay, maybe not dragons). Operationally though, the root zone uses two different keys, the mentioned Trust Anchor key (that is called the Key Signing Key or KSK for Continue reading

In 2017 we made two of our web optimisation products - Mirage and Rocket Loader - even faster! Combined, these products speed up around 1.2 billion web-pages a week. The products are both around 5 years old, so there was a big opportunity to update them for the brave new world of highly-tuned browsers, HTTP2 and modern Javascript tooling. We measured a performance boost that, very roughly, will save visitors to sites on our network between 50-700ms. Visitors that see content faster have much higher engagement and lower bounce rates, as shown by studies like Google’s. This really adds up, representing a further saving of 380 years of loading time each year and a staggering 1.03 petabytes of data transfer!

Cycling image Photo by Dimon Blr on Unsplash.

What Mirage and Rocket Loader do

Mirage and Rocket Loader both optimise the loading of a web page by reducing and deferring the number of assets the browser needs to request for it to complete HTML parsing and rendering on screen.

Mirage

Attention software engineering students: Cloudflare is coming to the University of Illinois at Urbana-Champaign and the University of Wisconsin–Madison, and we want to meet you! We will be attending UW–Madison’s Career Connection on Wednesday, February 7 and UIUC’s Startup Career Fair on Thursday, February 8. We’ll also be hosting tech talks at UIUC on Friday, February 2 at 6:00pm in 2405 Siebel Center and at UW–Madison on Tuesday, February 6 (time and location coming soon).

Cloudflare staff at YHack 2017. Photo courtesy Andrew Fitch.

Built in Champaign

In early 2016, Cloudflare opened an engineering office in Champaign, IL to build Argo Smart Routing. Champaign's proximity to the University of Illinois, one of the nation's top engineering schools, makes it an attractive place for high-tech companies to set up shop and for talented engineers to call home. Since graduating from UIUC in 2008, I've had opportunities to work on amazing software projects, growing technically and as a leader, all while enjoying the lifestyle benefits of Champaign (15 minute commute, anyone?).

Cloudflare has attended annual recruiting events at UIUC since the Champaign office was opened. This year, we've started to expand our search to other top engineering schools in the midwest. Continue reading

Cloudflare Workers Beta is now open!

Cloudflare Workers lets you run JavaScript on Cloudflare’s edge, deploying globally to over 120+ data centers around the world in less than 30 seconds. Your code can intercept and modify any request made to your website, make outbound requests to any URL on the Internet, and replace much of what you might need to configure your CDN to do today. Even better, it will do this from all our edge locations around the world, closer to many of your users than your origin servers can ever be. You will have a fully functional Turing-complete language in your fingertips which will allow you to build powerful applications on the edge. The only limit is your imagination.

To get started:

• Sign in to your account on cloudflare.com.
• Visit the Workers tab.
• Launch the editor.
• Write some code and save it.
• Go to the routes tab and prescribe on what requests you want to run Workers for

That’s it!

You can start by writing a simple ‘hello world’ script, but chances are that you are going write Workers that are more complicated. You can check out our page with recipes to:

• Run A/B tests on the Continue reading

This is a Korean translation of a prior post.

(이 글은 제 개인 블로그에 게시된 튜토리얼을 다시 올린 것입니다)

Rust에는 흥미로운 기능이 많지만 그중에도 강력한 매크로 시스템이 있습니다. 불행히도 The Book^[1]과 여러가지 튜토리얼을 읽고 나서도 서로 다른 요소의 복잡한 리스트를 처리하는 매크로를 구현하려고 하면 저는 여전히 어떻게 만들어야 하는지를 이해하는데 힘들어 하며, 좀 시간이 지나서 머리속에 불이 켜지는 듯한 느낌이 들면 그제서야 이것저것 매크로를 마구 사용하기 시작 합니다. :) (맞아요, 난-매크로를-써요-왜냐하면-함수나-타입-지정이나-생명주기를-쓰고-싶어하지-않아서 처럼과 같은 이유는 아니지만 다른 사람들이 쓰는걸 봤었고 실제로 유용한 곳이라면 말이죠)

CC BY 2.0 image by Conor Lawless

그래서 이 글에서는 제가 생각하는 그런 매크로를 쓰는 데 필요한 원칙을 설명하고자 합니다. 이 글에서는 The Book의 매크로 섹션을 읽어 보았고 기본적인 매크로 정의와 토큰 타입에 대해 익숙하다고 가정하겠습니다.

이 튜토리얼에서는 역폴란드 표기법 (Reverse Polish Notation, RPN)을 예제로 사용합니다. 충분히 간단하기 때문에 흥미롭기도 하고, 학교에서 이미 배워서 익숙할 지도 모르고요. 하지만 컴파일 시간에 정적으로 구현하기 위해서는 재귀적인 매크로를 사용해야 할 것입니다.

역폴란드 표기법(후위 또는 후치 표기법으로 불리기도 합니다)은 모든 연산에 스택을 사용하므로 연산 대상을 스택에 넣고 [이진] 연산자는 연산 대상 두개를 스택에서 가져와서 결과를 평가하고 다시 스택에 넣습니다. 따라서 다음과 같은 식을 생각해 보면:

2 3 + 4 *

이 식은 다음과 같이 해석됩니다:

1. 2 Continue reading

(This is a crosspost of a tutorial originally published on my personal blog)

Among other interesting features, Rust has a powerful macro system. Unfortunately, even after reading The Book and various tutorials, when it came to trying to implement a macro which involved processing complex lists of different elements, I still struggled to understand how it should be done, and it took some time till I got to that "ding" moment and started misusing macros for everything :) (ok, not everything as in the i-am-using-macros-because-i-dont-want-to-use-functions-and-specify-types-and-lifetimes everything like I've seen some people do, but anywhere it's actually useful)

CC BY 2.0 image by Conor Lawless

So, here is my take on describing the principles behind writing such macros. It assumes you have read the Macros section from The Book and are familiar with basic macros definitions and token types.

I'll take a Reverse Polish Notation as an example for this tutorial. It's interesting because it's simple enough, you might be already familiar with it from school, and yet to implement it statically at compile time, you already need to use a recursive macros approach.

Reverse Polish Notation (also called postfix notation) uses a stack for all its operations, Continue reading

For some businesses SEO is a bad word, and for good reason. Google and other search engines keep their algorithms a well-guarded secret making SEO implementation not unlike playing a game where the referee won’t tell you all the rules. While SEO experts exist, the ambiguity around search creates an opening for grandiose claims and misinformation by unscrupulous profiteers claiming expertise.

If you’ve done SEO research, you may have come across an admixture of legitimate SEO practices, outdated optimizations, and misguided advice. You might have read that using the keyword meta tag in your HTML will help your SEO (it won’t), that there’s a specific number of instances a keyword should occur on a webpage (there isn’t), or that buying links will improve your rankings (it likely won’t and will get the site penalized). Let’s sift through the noise and highlight some dos and don’ts for performance-based SEO in 2018.

SEO is dead, long live SEO!

Nearly every year since its inception, SEO is declared dead. It is true that the scope of best practices for search engines has narrowed over the years as search engines have become smarter, and much of the benefit Continue reading

This is a guest post by David Urbansky, CEO and Co-Founder of SEMKNOX and Site Search 360. David is a search enthusiast having built natural language search experiences for e-commerce sites and recipe search engines.

As a startup founder, there are always key product decisions to be made when Site Search 360, our key product, is embedded in one context versus another. I’d like to share some experiences, choices, and challenges in our process packaging Site Search 360 for Cloudflare Apps.

What is Site Search 360?

Site Search 360 is a search solution for websites. Offering a search bar on a website improves user experience tremendously if the site has more than just a handful of pages. According to a eConsultancy study, up to 30% of web visitors use the search feature on e-commerce sites and searchers sometimes make up 40% of the revenue. Additionally, Nielsen Group found that 51% of people who did not find what they were looking for with the first query, gave up without refining the search - the search had better work very well then.

Why use the Cloudflare App?

Considering these facts, almost every website should have a search feature. However, implementing Continue reading

It is not uncommon for countries around the world to interrupt Internet access for political reasons or because of social unrest. We've seen this many times in the past (e.g. Gabon, Syria, Togo).

Today, it appears that Internet access in the Democratic Republic of Congo has been greatly curtailed. The BBC reports that Internet access in the capital, Kinshasa was cut on Saturday and iAfrikan reports that the cut is because of anti-Kabila protests.

Our monitoring of traffic from the Democratic Republic of Congo shows a distinct drop off starting around midnight UTC on January 21, 2018. Traffic is down to about 1/3 of its usual level.

We'll update this blog once we have more information about traffic levels.

In April, we wrote about Web Cache Deception attacks, and how our customers can avoid them using origin configuration.

Read that blog post to learn about how to configure your website, and for those who are not able to do that, how to disable caching for certain URIs to prevent this type of attacks. Since our previous blog post, we have looked for but have not seen any large scale attacks like this in the wild.

Today, we have released a tool to help our customers make sure only assets that should be cached are being cached.

A brief re-introduction to Web Cache Deception attack

Recall that the Web Cache Deception attack happens when an attacker tricks a user into clicking a link in the format of http://www.example.com/newsfeed/foo.jpg, when http://www.example.com/newsfeed is the location of a dynamic script that returns different content for different users. For some website configurations (default in Apache but not in nginx), this would invoke /newsfeed with PATH_INFO set to /foo.jpg. If http://www.example.com/newsfeed/foo.jpg does not return the proper Cache-Control headers to tell a web cache not to cache the content, web caches may decide to cache Continue reading

역자주: 이 글은 Marek Majkowski의 https://blog.cloudflare.com/syn-packet-handling-in-the-wild/ 를 번역한 것입니다.

우리 Cloudflare 에서는 실제 인터넷상의 서버 운영 경험이 많습니다. 하지만 이런 흑마술 마스터하기를 게을리하지도 않습니다. 이 블로그에서는 인터넷 프로토콜의 여러 어두운 부분을 다룬 적이 있습니다: understanding FIN-WAIT-2 나 receive buffer tuning과 같은 것들입니다.

CC BY 2.0 image by Isaí Moreno

사람들이 충분히 신경쓰지 않는 주제가 하나 있는데, 바로 SYN 홍수(SYN floods) 입니다. 우리는 리눅스를 사용하고 있는데 리눅스에서 SYN 패킷 처리는 매우 복잡하다는 것을 알게 되었습니다. 이 글에서는 이에 대해 좀 더 알아 보도록 하겠습니다.

두개의 큐의 이야기

일단 만들어진 소켓에 대해 "LISTENING" TCP 상태에는 두개의 분리된 큐가 존재 합니다:

• SYN 큐
• Accept 큐

일반적으로 이 큐에는 여러가지 다른 이름이 붙어 있는데, "reqsk_queue", "ACK backlog", "listen backlog", "TCP backlog" 등이 있습니다만 혼란을 피하기 위해 위의 이름을 사용하도록 하겠습니다.

SYN 큐

SYN 큐는 수신 SYN 패킷^[1] (구체적으로는 struct inet_request_sock)을 저장합니다. 이는 SYN+ACK 패킷을 보내고 타임아웃시에 재시도하는 역할을 합니다. 리눅스에서 재시도 값은 다음과 같이 설정됩니다:

$ sysctl net.ipv4.tcp_synack_retries
net.ipv4.tcp_synack_retries = 5

문서를 보면 다음과 같습니다:

tcp_synack_retries - 정수

    수동 TCP 연결 시도에 대해서 SYNACK를 몇번 다시 보낼지를 지정한다.
    이 값은 255 이하이어야 한다. 기본값은 5이며, 1초의 초기 RTO값을 감안하면
    마지막 재전송은 31초  Continue reading

Democratizing the Internet and making new features available to all Cloudflare customers is a core part of what we do. We're proud to be early adopters and have a long record of adopting new standards early, such as HTTP/2, as well as features that are experimental or not yet final, like TLS 1.3 and SPDY.

Participating in the Internet democracy occasionally means that ideas and technologies that were once popular or ubiquitous on the net lose their utility as newer technologies emerge. SPDY is one such technology. Several years ago, Google drafted a proprietary and experimental new protocol called SPDY. SPDY offered many performance improvements over the aging HTTP/1.1 standard and these improvements resulted in significantly faster page load times for real-world websites. Stemming from its success, SPDY became the starting point for HTTP/2 and, when the new HTTP standard was finalized, the SPDY experiment came to an end where it gradually fell into disuse.

As a result, we're announcing our intention to deprecate the use of SPDY for connections made to Cloudflare's edge by February 21st, 2018.

Remembering 2012

Five and a half years ago, when the majority of the web was unencrypted and web developers Continue reading

Processor problems have been in the news lately, due to the Meltdown and Spectre vulnerabilities. But generally, engineers writing software assume that computer hardware operates in a reliable, well-understood fashion, and that any problems lie on the software side of the software-hardware divide. Modern processor chips routinely execute many billions of instructions in a second, so any erratic behaviour must be very hard to trigger, or it would quickly become obvious.

But sometimes that assumption of reliable processor hardware doesn’t hold. Last year at Cloudflare, we were affected by a bug in one of Intel’s processor models. Here’s the story of how we found we had a mysterious problem, and how we tracked down the cause.

CC-BY-SA-3.0 image by Alterego

Prologue

Back in February 2017, Cloudflare disclosed a security problem which became known as Cloudbleed. The bug behind that incident lay in some code that ran on our servers to parse HTML. In certain cases involving invalid HTML, the parser would read data from a region of memory beyond the end of the buffer being parsed. The adjacent memory might contain other customers’ data, which would then be returned in the HTTP response, and the result was Cloudbleed.

But Continue reading

Tell me if this sounds familiar: any connection from inside the corporate network is trusted and any connection from the outside is not. This is the security strategy used by most enterprises today. The problem is that once the firewall, or gateway, or VPN server creating this perimeter is breached, the attacker gets immediate, easy and trusted access to everything.

CC BY-SA 2.0 image by William Warby

There’s a second problem with the traditional security perimeter model. It either requires employees to be on the corporate network (i.e. physically in the office) or using a VPN, which slows down work because every page load makes extra round trips to the VPN server. After all this hassle, users on the VPN are still highly susceptible to phishing, man-in-the-middle and SQL injection attacks.

A few years ago, Google pioneered a solution for their own employees called BeyondCorp. Instead of keeping their internal applications on the intranet, they made them accessible on the internet. There became no concept of in or outside the network. The network wasn’t some fortified citadel, everything was on the internet, and no connections were trusted. Everyone had to prove they are who they say they are.

Continue reading

Here at Cloudflare, we have a lot of experience of operating servers on the wild Internet. But we are always improving our mastery of this black art. On this very blog we have touched on multiple dark corners of the Internet protocols: like understanding FIN-WAIT-2 or receive buffer tuning.

CC BY 2.0 image by Isaí Moreno

One subject hasn't had enough attention though - SYN floods. We use Linux and it turns out that SYN packet handling in Linux is truly complex. In this post we'll shine some light on this subject.

The tale of two queues

First we must understand that each bound socket, in the "LISTENING" TCP state has two separate queues:

• The SYN Queue
• The Accept Queue

In the literature these queues are often given other names such as "reqsk_queue", "ACK backlog", "listen backlog" or even "TCP backlog", but I'll stick to the names above to avoid confusion.

SYN Queue

The SYN Queue stores inbound SYN packets^[1] (specifically: struct inet_request_sock). It's responsible for sending out SYN+ACK packets and retrying them on timeout. On Linux the number of retries is configured with:

$ sysctl net.ipv4.tcp_synack_retries
net.ipv4.tcp_synack_retries = 5

The docs describe Continue reading

We just turned up Salt Lake City, Utah — Cloudflare's 120th data center. Salt Lake holds a special place in Cloudflare's history. I grew up in the region and still have family there. Back in 2004, Lee Holloway and I lived just up into the mountains in Park City when we built Project Honey Pot, the open source project that inspired the original idea for Cloudflare.

Salt Lake also holds a special place in the history of the Internet. The University of Utah, based there, was one of the original four Arpanet locations (along with UCLA, UC Santa Barbara, and the Stanford Research Institute). The school also educated the founders of great technology companies like Silicon Graphics, Adobe, Atari, Netscape, and Pixar. Many were graduates of the computer graphics department lead by Professors Ivan Sutherland and David Evans.

In 1980, when I was seven years old, my grandmother, who lived a few blocks from the University, gave me an Apple II+ for Christmas. I took to it like a duck to water. My mom enrolled in a continuing education computer course at the University of Utah teaching BASIC programming. I went with her to the classes. Unbeknownst to the Continue reading

Last week the news of two significant computer bugs was announced. They've been dubbed Meltdown and Spectre. These bugs take advantage of very technical systems that modern CPUs have implemented to make computers extremely fast. Even highly technical people can find it difficult to wrap their heads around how these bugs work. But, using some analogies, it's possible to understand exactly what's going on with these bugs. If you've found yourself puzzled by exactly what's going on with these bugs, read on — this blog is for you.

“When you come to a fork in the road, take it.” — Yogi Berra

Late one afternoon walking through a forest near your home and navigating with the GPS you come to a fork in the path which you’ve taken many times before. Unfortunately, for some mysterious reason your GPS is not working and being a methodical person you like to follow it very carefully.

Cooling your heels waiting for GPS to start working again is annoying because you are losing time when you could be getting home. Instead of waiting, you decide to make an intelligent guess about which path is most likely based on past experience and set Continue reading

For many of us, a New Year brings a renewed commitment to eat better, exercise regularly, and read more (especially the Cloudflare blog). But as we enter 2018, there is a unique and significant new commitment approaching -- protecting personal data and complying with the European Union’s (EU) General Data Protection Regulation (GDPR).

As many of you know by now, the GDPR is a sweeping new EU law that comes into effect on May 25, 2018. The GDPR harmonizes data privacy laws across the EU and mandates how companies collect, store, delete, modify and otherwise process personal data of EU citizens.

Since our founding, Cloudflare has believed that the protection of our customers’ and their end users’ data is essential to our mission to help build a better internet.

Image by GregMontani via Wikimedia Commons

Need a Data Processing Agreement?

As we explained in a previous blog post last August, Cloudflare has been working hard to achieve GDPR compliance in advance of the effective date, and is committed to help our customers and their partners prepare for GDPR compliance on their side. We understand that compliance with a new set of privacy laws can be challenging, and we are here Continue reading