grimd

README

grimd

⚡ Fast dns proxy, built to black-hole internet advertisements and malware servers. Capable of custom DNS.

Forked from looterz/grimd

Features

• DNS over UTP
• DNS over TCP
• DNS over HTTP(S) (DoH as per RFC-8484)
• Prometheus metrics API
• Custom DNS records support
• Blocklist fetching
• Hardcoded blocklist config
• Hardcoded whitelist config
• Fast startup (so it can be used with templating for service discovery)
• Small memory footprint (~50MBs with metrics and DoH enabled)

Installation

go install github.com/cottand/grimd@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/grimd
• use Docker compose YML
• use the Nix flake
  • nix run github:cottand/grimd

Detailed guides and resources can be found on the wiki.

Configuration

By default, grimd 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

$ grimd -help

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

Building

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

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

Building Docker

Run container and test

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

Speed

Incoming requests spawn a goroutine and are served concurrently, and the block cache resides in-memory to allow for rapid lookups, while answered queries are cached allowing grimd to serve thousands of queries at once while maintaining a memory footprint of under 30mb for 100,000 blocked domains!

Daemonize

You can find examples of different daemon scripts for grimd on the wiki.

Objectives

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

Non-objectives

Not keeping it simple: I would like grimd 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.