Firewalls have been around for many years, yet they are still misused almost as often as they are used. When people set up a Web server on their network, they typically open port 80 to the world. One of the most frequently used attacks is creating reverse shells over port 80. If you aren’t doing it, your network administrators aren’t giving you your money’s worth. If they haven’t done this yet, you may want to revisit your network security architecture and lock down those sites.”]
Source: https://www.darkreading.com/attacks-breaches/firewall-wish-list