Knot DNS Resolver

The Knot DNS Resolver is a caching full resolver implementation written in C and LuaJIT, both a resolver library and a daemon. The core architecture is tiny and efficient, and provides a foundation and a state-machine like API for extensions. There are three of those built-in - iterator, cache, validator, and most of the rich features are written in LuaJIT, Go and C. Batteries are included, but optional.

The LuaJIT modules, support for DNS privacy and DNSSEC, and persistent cache with low memory footprint make it a great personal DNS resolver or a research tool to tap into DNS data. TL;DR it's the OpenResty of DNS.

Several cache backends (LMDB, Redis and Memcached), strong filtering rules, and auto-configuration with etcd make it a great large-scale resolver solution.

The server adopts a different scaling strategy than the rest of the DNS recursors - no threading, shared-nothing architecture (except MVCC cache that may be shared) that allows you to pin instances on available CPU cores and grow by self-replication. You can start and stop additional nodes depending on the contention without downtime.

It also has strong support for DNS over TCP, notably TCP Fast-Open, query pipelining and deduplication, and response reordering.

Packages

Knot Resolver is packaged for Debian, Fedora, Ubuntu and openSUSE. See project page for more information.

Building from sources

The Knot DNS Resolver depends on the 2.1 version of the Knot DNS library, LuaJIT and libuv. See the Building project documentation page for more information.

Docker image

This is simple and doesn't require any dependencies or system modifications, just run:

$ docker run -it cznic/knot-resolver

See the build page hub.docker.com/r/cznic/knot-resolver for more information and options.

Running

The project builds a resolver library in the lib directory, and a daemon in the daemon directory. It requires no configuration or parameters to run a server on localhost.

$ kresd

See the documentation at knot-resolver.readthedocs.io for more options.

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