Pavel's blog about underlying Internet technologies

Pavel Odintsov

Please stop using DNS protocol for your application

At previous stages of my career I spent 5 years working with the DNS protocol and during this time I have collected a fairly large number of ways to shoot myself in the foot in a seemingly empty place. DNS is great for the task of bringing visitors to your

Capturing Packets in Linux at a Speed of Millions of Packets per Second without Using Third Party Libraries

My article will tell you how to receive 10 million packets per second without using any third party libraries such as Netmap, PF_RING, DPDK and others. We will do this using the usual Linux kernel version 3.16 and a certain amount of code in C and C ++. The

Making 35 000 000 IP lookup operations per second with Patricia tree

In this article I’ll try to make some performance evaluation of Patricia tree for purpose of IP address lookup in list of prefixes in C and C++ languages. Briefly, Patricia tree can help us to confirm that IP address 10.0.0.1 belongs or not to list of

It's just wrong to redefine IPFIX templates

In this blog post I'll cover pretty curious behaviour of IPFIX protocol on Juniper MX 204 boxes with JunOS 18.2R3-S6.5. This protocol is industry standard for exporting traffic observed by carrier grade routers or switches. NB! After followup investigation it was confirmed that issue was caused

Enabling IPv6 support for IPv4 only apps on Linux

To prove point that IPv6 is ready for production use I've been using IPv6 only setup on my Ubuntu PC for more then 4 months. To access legacy IPv4 Internet I use NAT64 gateway based on Tayga deployed on RockPro64 SBC in my cupboard: Most of the apps

Curious case of Martian traffic

At FastNetMon we work with UDP based protocols such us Netflow, IPFIX and sFlow on daily basis. These protocols are used by great variety of network equipment vendors to send information about traffic observed by network device to monitoring software. Today our technical support team received report from customer about

ICMPv6 and Google Cloud Compute Firewalls

For my work PC with Ubuntu Linux 22.04 LTS I use only IPv6 with my own NAT64 gateway which I run on RockPro64 to access resources without support for IPv6. Today I spent morning to enable native IPv6 for Google Cloud account we use for testing. Sadly I faced

My review of UKNOF 50

Last week I visited anniversary event of UKNOF 50 in London. I enjoyed both official and social part after it. It was definitely unusual to see DDoS related talk as keynote by A10 Networks followed by another DDoS related topic of Team Cymru. I well remember times when DDoS was

Please do not require AVX support for your software

Intro Hey! I'm Pavel from London, I'm CTO of FastNetMon and we run DDoS attack detection with on premise installations in 146 countries. This post was inspired by GitHub conversation which was triggered by Clickhouse's team decision to start asking for CPU feature called

Linux Kernel and BPF random opcode

In this blog I'll cover topic about random opcode. This opcode is extremely useful as it allows us to randomise behaviour of typically pretty deterministic BPF programs. I'll try to find out which kernel version included this new opcode. You may be familiar with great technology