UFW Firewall Policieshttps://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-16-04info on system logging: http://askubuntu.com/questions/184290/why-im-getting-this-ufw-block-in-my-syslogshttp://askubuntu.com/questions/828223/ufw-block-entries-in-the-log