leng

:zap: fast dns server, built to block advertisements and malware servers

Features

[x] DNS over UDP
[x] DNS over TCP
[x] DNS over HTTP(S) (DoH as per RFC-8484)
[x] Prometheus metrics API
[x] Custom DNS records support
[x] Blocklist fetching
[x] Hardcoded blocklist config
[x] Hardcoded whitelist config
[x] Fast startup and tiny image (so it can be quickly redeployed for use with templating for service discovery)
[x] Small memory footprint (~50MBs with metrics and DoH enabled)
[x] NixOS Flake for easy deployment

Installation

go install github.com/cottand/leng@latest

You can also

download one of the binary releases
use the Docker image
- docker run -d -p 53:53/udp -p 53:53/tcp -p 8080:8080/tcp ghcr.io/cottand/leng
use Docker compose YML
use the Nix flake
- to run: nix run github:cottand/leng
- or add as a NixOS module

Detailed guides and resources can be found in the docs website.

Configuration

By default, leng binds DNS to 0.0.0.0:53 and loads a few known blocklists. The default settings should be enough for most. See the wiki for the full config, including defaults and dynamic config reloading.

CLI Flags

$ leng -help

Usage of leng:
  -config string
        location of the config file (default "leng.toml")
  -update
        force an update of the blocklist database

Building

Requires golang 1.21 or higher, you build leng like any other golang application, for example to build for linux x64

env GOOS=linux GOARCH=amd64 go build -v github.com/cottand/leng

Building Docker

Run container and test

mkdir sources
docker build -t leng:latest -f docker/alpine.Dockerfile . && \
docker run -v $PWD/sources:/sources --rm -it -P --name leng-test leng:latest --config /sources/leng.toml --update

By default, if the program runs in a docker, it will automatically replace 127.0.0.1 in the default configuration with 0.0.0.0 to ensure that the API interface is available.

curl -H "Accept: application/json" http://127.0.0.1:55006/application/active

Objectives

[x] ~~ARM64 Docker builds~~
[ ] Better custom DNS support
- [x] ~~Dynamic config reload for custom DNS issue#16~~
- [x] ~~Fix multi-record responses issue#5~~
- [x] ~~DNS record CNAME following issue#1~~
- [ ] DNS record CNAME flattening a la cloudflare issue#27
- [ ] Service discovery integrations? issue#4
[x] Prometheus metrics exporter issue#3
[x] DNS over HTTPS #2
[ ] Add lots of docs

Non-objectives

Not keeping it simple: I would like leng to become a reliable custom DNS provider (like CoreDNS) and a reliable adblocker (like Blocky) that has the perfect set of features for self-hosters, and potentially for more critical setups.

cottand / leng

readme