SOCKMAP - TCP splicing of the future
February 18, 2019 1:13 PM
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Know your SCM_RIGHTS
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....
Optimizing HTTP/2 prioritization with BBR and tcp_notsent_lowat
October 12, 2018 12:00 PM
Getting the best end-user performance from HTTP/2 requires good support for resource prioritization. While most web servers support HTTP/2 prioritization, getting it to work well all the way to the browser requires a fair bit of coordination across the networking stack....
eBPF, Sockets, Hop Distance and manually writing eBPF assembly
March 29, 2018 10:43 AM
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. ...
SYN packet handling in the wild
January 15, 2018 1:49 PM
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....
MORE POSTS
October 23, 2017 12:57 PM
Why does one NGINX worker take all the load?
Scaling up TCP servers is usually straightforward. Most deployments start by using a single process setup. When the need arises more worker processes are added. ...
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August 18, 2017 5:40 PM
Broken packets: IP fragmentation is flawed
As opposed to the public telephone network, the internet has a Packet Switched design. But just how big can these packets be?...
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August 12, 2016 1:03 PM
This is strictly a violation of the TCP specification
I was asked to debug another weird issue on our network. Apparently every now and then a connection going through CloudFlare would time out with 522 HTTP error....
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August 02, 2016 2:01 PM
Introducing the p0f BPF compiler
Two years ago we blogged about our love of BPF (BSD packet filter) bytecode. Today we are very happy to open source another component of the bpftools: our p0f BPF compiler!...
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July 07, 2016 11:50 AM
Why we use the Linux kernel's TCP stack
A recent blog post posed the question Why do we use the Linux kernel's TCP stack?. It triggered a very interesting discussion on Hacker News....
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June 30, 2015 11:38 AM
How to achieve low latency with 10Gbps Ethernet
In a recent blog post we explained how to tweak a simple UDP application to maximize throughput. This time we are going to optimize our UDP application for latency. Fighting with latency is a great excuse to discuss modern features of multiqueue NICs. ...
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May 11, 2015 10:08 AM
CloudFlare "Interview Questions"
For quite some time we've been grilling our candidates about dirty corners of TCP/IP stack. Every engineer here must prove his/her comprehensive understanding of the full network stack. For example: what are the differences in checksumming algorithms between IPv4 and IPv6 stacks?...
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May 21, 2014 2:00 PM
BPF - the forgotten bytecode
Every once in a while I run into an obscure computer technology that is a hidden gem, which over the years has become mostly forgotten. This is exactly how I feel about the tcpdump tool and its kernel counterpart the packet filter interface....
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December 31, 2012 12:29 AM
Optimizing Your Linux Stack for Maximum Mobile Web Performance
We spend a lot of time at CloudFlare thinking about how to make the Internet fast on mobile devices. Currently there are over 1.2 billion active mobile users and that number is growing rapidly....
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June 28, 2012 6:48 AM
Why mobile performance is difficult
Mobile web browsing is very different, at the network level, to browsing on a desktop machine connected to the Internet. Yet both use the very same protocols, and although TCP was designed to perform well on the fixed-line Internet, it doesn't perform as well on mobile networks. ...
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June 25, 2012 7:14 AM
What makes SPDY speedy?
Google has proposed a new protocol for downloading web pages called SPDY and CloudFlare will shortly be making it available in beta form. SPDY is designed to make web browsing faster without replacing HTTP. ...
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June 21, 2012 6:29 AM
The bandwidth of a Boeing 747 and its impact on web browsing
Suppose you needed to transfer 1TB of data (perhaps your home movie collection) from San Francisco to London. What would be the fastest route? Put the disk on British Airways flight 286 at SFO, or transfer it across the Internet using a 100 Mbps connection?...
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June 12, 2012 10:38 PM
Mobile Web Performance: Optimizing TCP Congestion Control Algorithms
Transmission Control Protocol (TCP) is one of the primary protocols of the Internet. When you request a web page, the server responds with the data that makes up that page. The data is subdivided into discrete packets of data as they are sent across the Internet....
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October 19, 2011 2:45 AM
Stayin' Alive
We've been making a lot of improvements deep within CloudFlare that you'll start to see the benefits of over the coming weeks. As the changes graduate from our tests to full production, we'll try and give you a sense of what they are and why they're important. ...
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