CentOS 6 users, because Let’s Encrypt requires at least Python 2.7 to run you need to install a newer version. Luckily you can install 2.7 version aside to the 2.6 version already in your system. To do that you need to put in IUS repository. The installation process is actually very easy. All you need to do is:

yum install https://centos6.iuscommunity.org/ius-release.rpm

then:

yum install python27 python27-virtualenv

Once you did that, or if you’re on CentOS 7 make sure to have git installed by doing:

yum install git

Then download the Let’s Encrypt source code:

git clone https://github.com/letsencrypt/letsencrypt

Change directory and launch the tool for the firs time:

cd letsencrypt ./letsencrypt-