07abe7a8d6
This PR is the first part of work described in #6724. It reintroduces the tls-alpn-01 challenge in `acme` module, that was introduced by #5894 and reverted by #6100. The reason it was removed in the past is because some tests showed that with `1.0.2` branch of OpenSSL, the self-signed certificate containing the authorization key is sent to the requester even if the ALPN protocol `acme-tls/1` was not declared as supported by the requester during the TLS handshake. However recent discussions lead to the conclusion that this behavior was not a security issue, because first it is coherent with the behavior with servers that do not support ALPN at all, and second it cannot make a tls-alpn-01 challenge be validated in this kind of corner case. On top of the original modifications given by #5894, I merged the code to be up-to-date with our `master`, and fixed tests to match recent evolution about not displaying the `keyAuthorization` in the deserialized JSON form of an ACME challenge. I also move the logic to verify if ALPN is available on the current system, and so that the tls-alpn-01 challenge can be used, to a dedicated static function `is_available` in `acme.challenge.TLSALPN01`. This function is used in the related tests to skip them, and will be used in the future from Certbot plugins to trigger or not the logic related to tls-alpn-01, depending on the OpenSSL version available to Python. * Reimplement TLS-ALPN-01 challenge and standalone TLS-ALPN server from #5894. * Setup a class method to check if tls-alpn-01 is supported. * Add potential missing parameter in validation for tls-alpn * Improve comments * Make a class private * Handle old versions of openssl that do not terminate the handshake when they should do. * Add changelog * Explicitly close the TLS connection by the book. * Remove unused exception * Fix lint
Certbot is part of EFF’s effort to encrypt the entire Internet. Secure communication over the Web relies on HTTPS, which requires the use of a digital certificate that lets browsers verify the identity of web servers (e.g., is that really google.com?). Web servers obtain their certificates from trusted third parties called certificate authorities (CAs). Certbot is an easy-to-use client that fetches a certificate from Let’s Encrypt—an open certificate authority launched by the EFF, Mozilla, and others—and deploys it to a web server.
Anyone who has gone through the trouble of setting up a secure website knows what a hassle getting and maintaining a certificate is. Certbot and Let’s Encrypt can automate away the pain and let you turn on and manage HTTPS with simple commands. Using Certbot and Let's Encrypt is free, so there’s no need to arrange payment.
How you use Certbot depends on the configuration of your web server. The best way to get started is to use our interactive guide. It generates instructions based on your configuration settings. In most cases, you’ll need root or administrator access to your web server to run Certbot.
Certbot is meant to be run directly on your web server, not on your personal computer. If you’re using a hosted service and don’t have direct access to your web server, you might not be able to use Certbot. Check with your hosting provider for documentation about uploading certificates or using certificates issued by Let’s Encrypt.
Certbot 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. This client runs on Unix-based operating systems.
To see the changes made to Certbot between versions please refer to our changelog.
Until May 2016, Certbot was named simply letsencrypt or
letsencrypt-auto, depending on install method. Instructions
on the Internet, and some pieces of the software, may still refer to
this older name.
Contributing
If you'd like to contribute to this project please read Developer Guide.
This project is governed by EFF's Public Projects Code of Conduct.
How to run the client
The easiest way to install and run Certbot is by visiting certbot.eff.org, where you can find the correct instructions for many web server and OS combinations. For more information, see Get Certbot.
Understanding the client in more depth
To understand what the client is doing in detail, it's important to understand the way it uses plugins. Please see the explanation of plugins in the User Guide.
Links
Documentation: https://certbot.eff.org/docs
Software project: https://github.com/certbot/certbot
Notes for developers: https://certbot.eff.org/docs/contributing.html
Main Website: https://certbot.eff.org
Let's Encrypt Website: https://letsencrypt.org
Community: https://community.letsencrypt.org
ACME spec: http://ietf-wg-acme.github.io/acme/
ACME working area in github: https://github.com/ietf-wg-acme/acme
System Requirements
See https://certbot.eff.org/docs/install.html#system-requirements.
Current Features
- Supports multiple web servers:
- apache/2.x
- nginx/0.8.48+
- webroot (adds files to webroot directories in order to prove control of domains and obtain certs)
- standalone (runs its own simple webserver to prove you control a domain)
- other server software via third party plugins
- 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 an interactive text UI, or can be driven entirely from the command line.
- Free and Open Source Software, made with Python.
For extensive documentation on using and contributing to Certbot, go to https://certbot.eff.org/docs. If you would like to contribute to the project or run the latest code from git, you should read our developer guide.