This is a tiny, auditable script that you can throw on any secure machine to issue and renew Let's Encrypt certificates with DNS validation.
Using DNS challenges from the ACME RFC to create TLS certificate allows you to create wildcard certificates, to renew certificates without any service interruption and to keep you TLS private key secure (only the CSR request has to be shared with the computer running acme-dns-tiny and the script can be run without root/administrator privileges).
Since this script has to access your private ACME account key and must have the rights to update the DNS records of your DNS server, this code has been designed to be as tiny as possible (currently less than 400 lines).
PLEASE READ THE SOURCE CODE! YOU MUST TRUST IT! IT HANDLES YOUR ACCOUNT PRIVATE KEY AND UPDATES SOME OF YOUR DNS RESOURCES !
The only prerequisites are Python 3 (at least 3.4), OpenSSL and the dnspython module.
For the dnspython module, be aware that it won't work with release 1.14.0, because this one have a bug with dynamic DNS updates. You should either use an older version from dnspython3 module (python3 specific code) or any release of dnspython module (pyhton2 and python3 merged code) since 1.15.0.
Note: this script is a fork of the acme-tiny project which uses ACME HTTP verification to create signed certificates.
If this script is useful to you, please donate to the EFF. I don't work there, but they do fantastic work.
How to use this script
See the HowTo Use wiki page for main informations.
You may be interested by the HowTo Setup with BIND9 page too which show a step by step example to set up the script with a BIND9 DNS server.
Note that, this script can be run on any secure machine which have access to Internet and your public DNS server.
The biggest problem you'll likely come across while setting up and running this script is permissions.
You want to limit access for this script to:
- Your account private key
- Your Certificate Signing Request (CSR) file (without your private domain key)
- Your configuration file (which contains the secret to do dynamic DNS updates)
I'd recommend to create a user specifically to run this script and the above files. This user should NOT have access to your private domain key!
BE SURE TO:
- Backup your account private key (e.g.
- Don't allow this script to be able to read your domain private key!
- Don't allow this script to be run as root!
- Understand and configure correctly your cron job to do all your needs ! (write it with your preferred language to manage your server)
This project has a very, very limited scope and codebase. The project is happy to receive bug reports and pull requests, but please don't add any new features. This script must stay under ~400 lines of code to ensure it can be easily audited by anyone who wants to run it.
If you want to add features for your own setup to make things easier for you, please do! It's open source, so feel free to fork it and modify as necessary.