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Michael BrownandGitHub
9f8e4507ad
Certificates are public information by design: they are provided by
web servers without any prior authentication required. In a public
key cryptographic system, only the private key is secret information.
The private key file is already created as accessible only to the root
user with mode 0600, and these file permissions are set before any key
content is written to the file. There is no window within which an
attacker with access to the containing directory would be able to read
the private key content.
Older versions of Certbot (prior to 0.29.0) would create private key
files with mode 0644 and rely solely on the containing directory
permissions to restrict access. We therefore cannot (yet) set the
relevant default directory permissions to 0755, since it is possible
that a user could install Certbot, obtain a certificate, then
downgrade to a pre-0.29.0 version of Certbot, then obtain another
certificate. This chain of events would leave the second
certificate's private key file exposed.
As a compromise solution, document the fact that it is safe for the
common case of non-downgrading users to change the permissions of
/etc/letsencrypt/{live,archive} to 0755, and explain how to use chgrp
and chmod to make the private key file readable by a non-root service
user.
This provides guidance on the simplest way to solve the common problem
of making keys and certificates usable by services that run without
root privileges, with no requirement to create a custom (and hence
error-prone) executable hook.
Remove the existing custom executable hook example, so that the
documentation contains only the simplest and safest way to solve this
very common problem.
Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>
.. This file contains a series of comments that are used to include sections of this README in other files. Do not modify these comments unless you know what you are doing. tag:intro-begin 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 <https://certbot.eff.org>`_. It generates instructions based on your configuration settings. In most cases, you’ll need `root or administrator access <https://certbot.eff.org/faq/#does-certbot-require-root-administrator-privileges>`_ 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 <https://github.com/ietf-wg-acme/acme/blob/master/draft-ietf-acme-acme.md>`_ 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 <https://github.com/certbot/certbot/blob/master/certbot/CHANGELOG.md>`_. 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 <https://certbot.eff.org/docs/contributing.html>`_. This project is governed by `EFF's Public Projects Code of Conduct <https://www.eff.org/pages/eppcode>`_. .. _installation: 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 <https://certbot.eff.org/docs/install.html>`_. .. _certbot.eff.org: https://certbot.eff.org/ 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 <https://certbot.eff.org/docs/using.html#plugins>`_ in the User Guide. Links ===== .. Do not modify this comment unless you know what you're doing. tag:links-begin 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 |build-status| |container| .. |build-status| image:: https://travis-ci.com/certbot/certbot.svg?branch=master :target: https://travis-ci.com/certbot/certbot :alt: Travis CI status .. |container| image:: https://quay.io/repository/letsencrypt/letsencrypt/status :target: https://quay.io/repository/letsencrypt/letsencrypt :alt: Docker Repository on Quay.io .. Do not modify this comment unless you know what you're doing. tag:links-end System Requirements =================== See https://certbot.eff.org/docs/install.html#system-requirements. .. Do not modify this comment unless you know what you're doing. tag:intro-end .. Do not modify this comment unless you know what you're doing. tag:features-begin 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 <https://certbot.eff.org/docs/using.html#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. .. Do not modify this comment unless you know what you're doing. tag:features-end 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 <https://certbot.eff.org/docs/contributing.html>`_.