The Let’s Encrypt Client is BETA SOFTWARE. It contains plenty of bugs and rough edges, and should be tested thoroughly in staging environments before use on production systems.
About the Let’s Encrypt Client¶
The Let’s Encrypt Client is a fully-featured, extensible client for the Let’s Encrypt CA (or any other CA that speaks the ACME protocol) that can automate the tasks of obtaining certificates and configuring webservers to use them.
letsencrypt is packaged for your OS, you can install it from there, and
run it by typing
letsencrypt. Because not all operating systems have
packages yet, we provide a temporary solution via the
wrapper script, which obtains some dependencies from your OS and puts others
in a python virtual environment:
user@webserver:~$ git clone https://github.com/letsencrypt/letsencrypt user@webserver:~$ cd letsencrypt user@webserver:~/letsencrypt$ ./letsencrypt-auto --help
Or for full command line help, type:
./letsencrypt-auto --help all
letsencrypt-auto updates to the latest client release automatically. And
letsencrypt-auto is a wrapper to
letsencrypt, it accepts exactly
the same command line flags and arguments. More details about this script and
other installation methods can be found in the User Guide.
How to run the client¶
In many cases, you can just run
letsencrypt, and the
client will guide you through the process of obtaining and installing certs
You can also tell it exactly what you want it to do from the command line.
For instance, if you want to obtain a cert for
otherthing.net, using the Apache plugin to both
obtain and install the certs, you could do this:
./letsencrypt-auto --apache -d thing.com -d www.thing.com -d otherthing.net
(The first time you run the command, it will make an account, and ask for an
email and agreement to the Let’s Encrypt Subscriber Agreement; you can
automate those with
If you want to use a webserver that doesn’t have full plugin support yet, you can still use “standalone” or “webroot” plugins to obtain a certificate:
./letsencrypt-auto certonly --standalone --email firstname.lastname@example.org -d thing.com -d www.thing.com -d otherthing.net
The Let’s Encrypt Client presently only runs on Unix-ish OSes that include
Python 2.6 or 2.7; Python 3.x support will be added after the Public Beta
launch. The client requires root access in order to write to
bind to ports 80 and 443 (if you use the
standalone plugin) and to read and
modify webserver configurations (if you use the
plugins). If none of these apply to you, it is theoretically possible to run
without root privileges, but for most users who want to avoid running an ACME
client as root, either letsencrypt-nosudo or simp_le are more appropriate choices.
The Apache plugin currently requires a Debian-based OS with augeas version 1.0; this includes Ubuntu 12.04+ and Debian 7+.
- Supports multiple web servers:
- apache/2.x (working on Debian 8+ and Ubuntu 12.04+)
- standalone (runs its own simple webserver to prove you control a domain)
- webroot (adds files to webroot directories in order to prove control of domains and obtain certs)
- nginx/0.8.48+ (highly experimental, not included in letsencrypt-auto)
- The private key is generated locally on your system.
- Can talk to the Let’s Encrypt CA or optionally to other ACME compliant services.
- Can get domain-validated (DV) certificates.
- Can revoke certificates.
- Adjustable RSA key bit-length (2048 (default), 4096, ...).
- Can optionally install a http -> https redirect, so your site effectively runs https only (Apache only)
- Fully automated.
- Configuration changes are logged and can be reverted.
- Supports ncurses and text (-t) UI, or can be driven entirely from the command line.
- Free and Open Source Software, made with Python.