dnsdist-autoconf

Simple dnsdist config generator made for human.

Prebuilt binaries might be found in releases or from the CI below.

Integrated Docker image: Docker Hub

Features

• Set different DNS servers for different domains
• Integrated felixonmars/dnsmasq-china-list rules
• Automatically probe Active Directory

Usage

I Just Wanna Run

An example config file is at examples/autoconf.toml. dnsdist-autoconf will search for a autoconf.toml file under the config folder.

# generate the config
dnsdist-autoconf -config .
# check the config grammar (important, since the author is not very confident)
dnsdist -C dnsdist.conf --check-config
# run it!
dnsdist -C dnsdist.conf

Use Hosted Dnsdist in Docker

The docker image will rerun dnsdist-autoconf every night to update dynamic config.

Set REMOTE_CONFIG and autoconf.toml will be updated too.

Option 1: directly run the docker image

0. Put a dnsdist-autoconf config toml file into /etc/dnsdist
1. Run an instance of jamesits/dnsdist-autoconf:latest

docker pull jamesits/dnsdist-autoconf:latest
docker run --rm --name=dnsdist-autoconf_1 -p=53:53/udp -p=53:53/tcp -p=8083:80/tcp --dns=1.1.1.1 --dns=8.8.8.8 -v=/etc/dnsdist:/etc/dnsdist jamesits/dnsdist-autoconf:latest

Option 2: manage it with systemd

0. Make sure your current OS have good DNS (at least can connect to the Docker registry and let dnsdist-autoconf finish probing services)
1. Put dnsdist-autoconf.service in this repo to /usr/lib/systemd/system
2. Put a dnsdist-autoconf config toml file into /etc/dnsdist
3. Start (and optionally enable) the dnsdist-autoconf.service systemd unit

Example:

mkdir -p /usr/lib/systemd/system
mkdir -p /etc/dnsdist
wget https://github.com/Jamesits/dnsdist-autoconf/raw/master/docker/dnsdist-autoconf.service -O /usr/lib/systemd/system/dnsdist-autoconf.service
wget https://github.com/Jamesits/dnsdist-autoconf/raw/master/examples/autoconf.toml -O /etc/dnsdist/autoconf.toml
systemctl daemon-reload
systemctl enable --now dnsdist-autoconf.service

Building

Use Go 1.10 or higher.

Caveats

dnsdist version compatibility

We only support dnsdist version 1.4 and later. Although there are some cases running dnsdist <1.4 with it, these cases will less likely be supported.

Disable systemd-resolved

systemd-resolved will take up port 53 on Ubuntu 17.04 onwards. To disable it:

0. Make sure your hostname resolves in /etc/hosts
1. If your /etc/resolv.conf is a symlink, delete it and recreate it, type in nameserver 8.8.8.8 or any other working DNS server
2. systemctl disable --now systemd-resolved.service
3. systemctl mask systemd-resolved.service
4. Config your DHCP client to use the appropriate DNS config. For example, if using NetworkManager, add dns=default under [main] section of /etc/NetworkManager/NetworkManager.conf.

Active Directory

We make a simple assumption that every DC have DNS roles installed, since we can only get LDAP/Kerberos server list from DNS queries, and quering any other config requires much more complex protocols.

ulimit (Too many open files)

The generated config might cause dnsdist to use a lot file descriptors.

Warning, this configuration can use more than 1220 file descriptors, web server and console connections not included, and the current limit is 1024.
You can increase this value by using LimitNOFILE= in the systemd unit file or ulimit.

Quick fix if you are running directly in a shell:

# you might need root privilege
ulimit -u unlimited
dnsdist -C dnsdist.conf

Fix if you are running in systemd:

mkdir -p /etc/systemd/system/dnsdist.service.d
echo -e "[Service]\nLimitNOFILE=16384\n" > /etc/systemd/system/dnsdist.service.d/ulimit.conf
systemctl daemon-reload