What is DNSMasker?

Short version: It's a HTTP wrapper for DNSMasq and its hosts file.

Motivations

• Delegate DNS management while maintaining the smallest footprint ever.
• Do whatever is necessary to keep customized code to a minimum. I wanted to use off-the-shelf components where possible.
• Provide a convenient interface for managing DNS records.
• Do as little as possible as root.

Usage

Visit the Swagger or Redoc documentation at /docs/ or /redoc, respectively. It's a simple path-based HTTP API.

Token File

The token file is a brain-dead access control mechanism. It is a file that contains a single "API Key" per line. You are free to mint and distribute API Keys that users can include in the x-api-token header with their requests.

Hosts File

The hosts file is created and managed by dnsmasker. It follows the standard hosts file convention: IP address <tab> Name

Setup

First-time Setup

$ touch hosts
$ tr -dc A-Za-z0-9 </dev/urandom | head -c 16 > tokens

Sudoers configuration

# allow 'user' to hup dnsmasq
user ALL=(root) pkill -HUP dnsmasq

dnsmasq.conf

Modify the dnsmasq configuration file to use a custom hosts file and prevent any forwarding loops.

# Use a custom hosts file
no-hosts
addn-hosts=/home/user/pydnsmasker/hosts

# Prevent unnecessary forwarding
domain-needed
bogus-priv
no-resolv
local=/domain/
local=/domain2/

Python Application

$ python -m venv .venv
$ source .venv/bin/acticate
$ pip install -r requirements.txt

# run the application
$ fastapi run server.py --host 0.0.0.0 --port 8000

Examples

Add multiple A records for the 'ceph.lan' service

$ read -s -p "enter your api key: " TOKEN
$ export $TOKEN
$ for num in {1..60}; do result=$(curl -s -H "x-api-token:$TOKEN" "http://localhost:8000/service/ceph.lan/10.10.10.1$num" -X POST); done;
$ host ceph.lan
ceph.lan has address 10.10.10.116
ceph.lan has address 10.10.10.132
ceph.lan has address 10.10.10.11
ceph.lan has address 10.10.10.133
ceph.lan has address 10.10.10.117
ceph.lan has address 10.10.10.134
ceph.lan has address 10.10.10.19
...
ceph.lan has address 10.10.10.160

Remove an A record for the 'ceph.lan' service

$ read -s -p "enter your api key: " TOKEN
$ export $TOKEN
$ curl -s -H "x-api-token:$TOKEN" "http://localhost:8000/service/ceph.lan/10.10.10.160" -X DELETE | jq
{
  "ceph.lan": [
    "10.10.10.11",
    "10.10.10.12",
    "10.10.10.13",
    "10.10.10.14",
    "10.10.10.15",
    "10.10.10.16",
    "10.10.10.17",
    "10.10.10.18",
    ...
    "10.10.10.159",
  ]
}

License (MIT)

Copyright 2024 Kevin Wojkovich

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.