# Get Certbot

Table of Contents

- About Certbot
- System Requirements
- Alternate installation methods
  - Certbot-Auto
  - Problems with Python virtual environment
  - Running with Docker
  - Operating System Packages
  - Installing from source

## About Certbot

Certbot is packaged for many common operating systems and web servers. Check whether `certbot` (or `letsencrypt`) is packaged for your web server’s OS by visiting certbot.eff.org, where you will also find the correct installation instructions for your system.

Note

Unless you have very specific requirements, we kindly suggest that you use the Certbot packages provided by your package manager (see certbot.eff.org). If such packages are not available, we recommend using `certbot-auto`, which automates the process of installing Certbot on your system.

## System Requirements

Certbot currently requires Python 2.7 or 3.4+ running on a UNIX-like operating system. By default, it requires root access in order to write to `/etc/letsencrypt`, `/var/log/letsencrypt`, `/var/lib/letsencrypt`; to bind to ports 80 and 443 (if you use the `standalone` plugin) and to read and modify webserver configurations (if you use the `apache` or `nginx` 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 an OS with augeas version 1.0; currently it supports modern OSes based on Debian, Fedora, SUSE, Gentoo and Darwin.

Additional integrity verification of certbot-auto script can be done by verifying its digital signature. This requires a local installation of gpg2, which comes packaged in many Linux distributions under name gnupg or gnupg2.

Installing with `certbot-auto` requires 512MB of RAM in order to build some of the dependencies. Installing from pre-built OS packages avoids this requirement. You can also temporarily set a swap file. See “Problems with Python virtual environment” below for details.

## Alternate installation methods

If you are offline or your operating system doesn’t provide a package, you can use an alternate method for installing `certbot`.

### Certbot-Auto

The `certbot-auto` wrapper script installs Certbot, obtaining some dependencies from your web server OS and putting others in a python virtual environment. You can download and run it as follows:

    user@webserver:~$ wget https://dl.eff.org/certbot-auto
    user@webserver:~$ chmod a+x ./certbot-auto
    user@webserver:~$ ./certbot-auto --help

To check the integrity of the `certbot-auto` script, you can use these steps:

    user@webserver:~$ wget -N https://dl.eff.org/certbot-auto.asc
    user@webserver:~$ gpg2 --keyserver pool.sks-keyservers.net --recv-key A2CFB51FA275A7286234E7B24D17C995CD9775F2
    user@webserver:~$ gpg2 --trusted-key 4D17C995CD9775F2 --verify certbot-auto.asc certbot-auto

The output of the last command should look something like:

    gpg: Signature made Wed 02 May 2018 05:29:12 AM IST
    gpg:                using RSA key A2CFB51FA275A7286234E7B24D17C995CD9775F2
    gpg: key 4D17C995CD9775F2 marked as ultimately trusted
    gpg: checking the trustdb
    gpg: marginals needed: 3  completes needed: 1  trust model: pgp
    gpg: depth: 0  valid:   2  signed:   2  trust: 0-, 0q, 0n, 0m, 0f, 2u
    gpg: depth: 1  valid:   2  signed:   0  trust: 2-, 0q, 0n, 0m, 0f, 0u
    gpg: next trustdb check due at 2027-11-22
    gpg: Good signature from "Let's Encrypt Client Team <letsencrypt-client@eff.org>" [ultimate]

The `certbot-auto` command updates to the latest client release automatically. Since `certbot-auto` is a wrapper to `certbot`, it accepts exactly the same command line flags and arguments. For more information, see Certbot command-line options.

For full command line help, you can type:

    ./certbot-auto --help all

### Problems with Python virtual environment

On a low memory system such as VPS with less than 512MB of RAM, the required dependencies of Certbot will fail to build. This can be identified if the pip outputs contains something like `internal compiler error: Killed (program cc1)`. You can workaround this restriction by creating a temporary swapfile:

    user@webserver:~$ sudo fallocate -l 1G /tmp/swapfile
    user@webserver:~$ sudo chmod 600 /tmp/swapfile
    user@webserver:~$ sudo mkswap /tmp/swapfile
    user@webserver:~$ sudo swapon /tmp/swapfile

Disable and remove the swapfile once the virtual environment is constructed:

    user@webserver:~$ sudo swapoff /tmp/swapfile
    user@webserver:~$ sudo rm /tmp/swapfile

### Running with Docker

Docker is an amazingly simple and quick way to obtain a certificate. However, this mode of operation is unable to install certificates or configure your webserver, because our installer plugins cannot reach your webserver from inside the Docker container.

Most users should use the operating system packages (see instructions at certbot.eff.org) or, as a fallback, `certbot-auto`. You should only use Docker if you are sure you know what you are doing and have a good reason to do so.

You should definitely read the Where are my certificates? section, in order to know how to manage the certs manually. Our ciphersuites page provides some information about recommended ciphersuites. If none of these make much sense to you, you should definitely use the certbot-auto method, which enables you to use installer plugins that cover both of those hard topics.

If you’re still not convinced and have decided to use this method, from the server that the domain you’re requesting a certficate for resolves to, install Docker, then issue a command like the one found below. If you are using Certbot with the Standalone plugin, you will need to make the port it uses accessible from outside of the container by including something like `-p 80:80` or `-p 443:443` on the command line before `certbot/certbot`.

    sudo docker run -it --rm --name certbot \
                -v "/etc/letsencrypt:/etc/letsencrypt" \
                -v "/var/lib/letsencrypt:/var/lib/letsencrypt" \
                certbot/certbot certonly

Running Certbot with the `certonly` command will obtain a certificate and place it in the directory `/etc/letsencrypt/live` on your system. Because Certonly cannot install the certificate from within Docker, you must install the certificate manually according to the procedure recommended by the provider of your webserver.

There are also Docker images for each of Certbot’s DNS plugins available at https://hub.docker.com/u/certbot which automate doing domain validation over DNS for popular providers. To use one, just replace `certbot/certbot` in the command above with the name of the image you want to use. For example, to use Certbot’s plugin for Amazon Route 53, you’d use `certbot/dns-route53`. You may also need to add flags to Certbot and/or mount additional directories to provide access to your DNS API credentials as specified in the DNS plugin documentation. If you would like to obtain a wildcard certificate from Let’s Encrypt’s ACMEv2 server, you’ll need to include `--server https://acme-v02.api.letsencrypt.org/directory` on the command line as well.

For more information about the layout of the `/etc/letsencrypt` directory, see Where are my certificates?.

### Operating System Packages

Arch Linux

    sudo pacman -S certbot

Debian

If you run Debian Stretch or Debian Sid, you can install certbot packages.

    sudo apt-get update
    sudo apt-get install certbot python-certbot-apache

If you don’t want to use the Apache plugin, you can omit the `python-certbot-apache` package. Or you can install `python-certbot-nginx` instead.

Packages exist for Debian Jessie via backports. First you’ll have to follow the instructions at http://backports.debian.org/Instructions/ to enable the Jessie backports repo, if you have not already done so. Then run:

    sudo apt-get install certbot python-certbot-apache -t jessie-backports

Fedora

    sudo dnf install certbot python2-certbot-apache

FreeBSD

> - Port: `cd /usr/ports/security/py-certbot && make install clean`
> - Package: `pkg install py27-certbot`

Gentoo

The official Certbot client is available in Gentoo Portage. If you want to use the Apache plugin, it has to be installed separately:

    emerge -av app-crypt/certbot
    emerge -av app-crypt/certbot-apache

When using the Apache plugin, you will run into a “cannot find an SSLCertificateFile directive” or “cannot find an SSLCertificateKeyFile directive for certificate” error if you’re sporting the default Gentoo `httpd.conf`. You can fix this by commenting out two lines in `/etc/apache2/httpd.conf` as follows:

Change

    <IfDefine SSL>
    LoadModule ssl_module modules/mod_ssl.so
    </IfDefine>

to

    #<IfDefine SSL>
    LoadModule ssl_module modules/mod_ssl.so
    #</IfDefine>

For the time being, this is the only way for the Apache plugin to recognise the appropriate directives when installing the certificate. Note: this change is not required for the other plugins.

NetBSD

> - Build from source: `cd /usr/pkgsrc/security/py-certbot && make install clean`
> - Install pre-compiled package: `pkg_add py27-certbot`

OpenBSD

> - Port: `cd /usr/ports/security/letsencrypt/client && make install clean`
> - Package: `pkg_add letsencrypt`

Other Operating Systems

OS packaging is an ongoing effort. If you’d like to package Certbot for your distribution of choice please have a look at the Packaging Guide.

### Installing from source

Installation from source is only supported for developers and the whole process is described in the Developer Guide.

Warning

Please do not use `python setup.py install`, `python pip install .`, or `easy_install .`. Please do not attempt the installation commands as superuser/root and/or without virtual environment, e.g. `sudo python setup.py install`, `sudo pip install`, `sudo ./venv/bin/...`. These modes of operation might corrupt your operating system and are not supported by the Certbot team!