SSL and TLS

Automatic and free certificates via "Let's Encrypt"

Download the "Let's Encrypt" client:

$ sudo apt-get install python-letsencrypt-apache

Get a new SSL certificate by running
```
$ sudo letsencrypt --apache -d example.com -d www.example.com
```
where you replace example.com with your domain name and optionally add even more subdomains after -d options.
Check if your site is available via HTTPS now and perhaps also check your configuration using an online tool
Set up a cron job in the root user's crontab to attempt automatic renewal of the certificate twice a day (at random times), e.g.:
```
14 1,11 * * * export PATH=/usr/sbin:/usr/bin:/sbin:/bin && letsencrypt renew > /path/to/log-file.log 2>&1
```