Certbot

Letsencrypt.org

See Letsencrypt.org

Ubuntu

Install:

sudo apt-get update
sudo apt-get install software-properties-common
sudo add-apt-repository universe
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update

sudo apt-get install certbot python-certbot-apache

Auto install certificates:

sudo certbot --apache

Or just get a certificate:

sudo certbot certonly --apache

Test automatic renewal:

sudo certbot renew --dry-run

ref: https://certbot.eff.org/lets-encrypt/ubuntubionic-apache

CentOS

Install:

wget https://dl.eff.org/certbot-auto
sudo mv certbot-auto /usr/local/bin/certbot-auto
sudo chown root /usr/local/bin/certbot-auto
sudo chmod 0755 /usr/local/bin/certbot-auto

Auto install certificates:

sudo /usr/local/bin/certbot-auto --apache

Or just get a certificate:

sudo /usr/local/bin/certbot-auto certonly --apache

Automatic renewal: (crontab)

echo "0 0,12 * * * root python -c 'import random; import time; time.sleep(random.random() * 3600)' && /usr/local/bin/certbot-auto renew" | sudo tee -a /etc/crontab > /dev/null

ref: https://certbot.eff.org/lets-encrypt/centos6-apache