In this post, we describe the differences between the two widespread protocols for DNS encryption: DNS-over-TLS (DoT) and DNS-over-HTTPS (DoH). We compare the technical aspects of those protocols as well as their implications on user privacy. We also introduce Knot Resolver’s new built-in DoH support and explain some of our design decisions behind DoH.
The Internet is flooded with news about a new attack against DNS protocol called Side channel AttackeD DNS, or in short SAD DNS. The attack is described in detail in Cloudflare’s blog and I strongly recommend you to read it to grasp how it works and why it is novel.
Ten years ago, mojeID, an authenticated online identity service, was launched. This happened after a three-month trial run and about a year after the announcement of the intention to the local online community. For me personally, October 26, 2010 was only my 42nd day in CZ.NIC, where I was brought by a somewhat mysterious-looking job advertisement promising, among other things, a chance to witness the infrastructure of the Czech Internet being formed. From the very beginning, MojeID has been associated with great expectations and from today’s point of view it can be said with a little exaggeration that we were ahead of our times with it. But let’s get back to that later.
Recently, version 3.0 of Knot DNS – an open-source implementation of an authoritative DNS server – has been released. Despite the version number, the software isn’t changing much. There are slightly more new features than in common feature releases such as 2.9. However, the features added in 3.0 don’t change any behaviour, unless the user turns them on. The migration from 2.9 to 3.0 is therefore seamless.
CZ.NIC Laboratories released the first public version of DNS Probe. It is a high-performance DNS traffic capture tool developed as a part of the ADAM project. Its essential function is to listen on a network interface, capture DNS traffic (both UDP and TCP), pair DNS queries with corresponding responses, and export consolidated records about every single DNS transaction observed on the wire. DNS Probe can be deployed either on the same machine as the DNS server, or on a separate monitoring computer that receives an exact copy of the DNS server’s traffic (e.g. via switch port mirroring).
We have released a new version of Turris OS 5.0. It is based on top of OpenWrt 19.07.3 with our patches and feed for all of Turris routers. In this article, we will go through new features and changes, including experimental migration from the Turris OS 3.x version. We will mention a few obstacles we faced during the development and introduce several features you can expect in future releases.
DNS resolvers are constantly adding features while not removing any, but this trend cannot continue indefinitely because the software would eventually break under its own weight. Which features are used in practice and which can be safely removed? We present preliminary results of a survey among DNS resolver administrators, and also invite readers to participate in cross-vendor survey which is open until 2020-06-30.
As a planned milestone in the ADAM project (Advanced DNS Analytics and Measurements), CZ.NIC Laboratories in cooperation with CSIRT.CZ are about to commence regular operation of DNS crawler. This tool will periodically scan all second-level domains under TLD .cz, collect selected publicly available data about them, and process them further in various ways. Despite the name, the DNS crawler will collect data not only from DNS; it will also communicate with each domain’s web and e-mail server. We plan to run the tool with two periods: most data items will be collected on a weekly basis, only the contents of main web pages <domain>.cz or www.<domain>.cz will be retrieved less frequently – once a month. In addition, newly registered domains will be subject to an extra scrutiny: their data will be retrieved daily for the first two weeks of their existence. The DNS crawler software is designed so as to minimize the impact on the operation of second-level domains and network infrastructure in general. Data obtained from the crawler will be used for these principal purposes:
This article describes NXNSAttack, a newly discovered DNS protocol vulnerability which affects most recursive DNS resolvers. It allows to execute random subdomain attack using DNS delegation mechanism, resulting in big packet amplification factor.
Now more then ever, people connect and work remotely. Everybody uses some kind of VPN, at least in the tech world. The new, trendy and cool way of doing VPNs is Wireguard. Everybody speaks about it and since March it is finally a part of Linux kernel. Its advantages are that it is setup in more straight forward way than alternatives and that it is blazingly fast.