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
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.
Perfect locality and three epic SystemTap scripts
In a recent blog post we discussed epoll behavior causing uneven load among NGINX worker processes. We suggested a work around - the REUSEPORT socket option.
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.
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?