| Types of firewalls | What do they do |
| Proxy firewall | Proxy firewall serves as the gateway from one network to another for a specific application. This can provide additional functionality such as content caching and security by preventing direct connections from outside the network. |
| Stateful inspection firewall | Stateful inspection firewall allows or blocks traffic based on state, port, and protocol. It monitors all activity from the opening of a connection until it is closed. Also decisions are made based on both administrator-defined rules as well as context. |
| Unified threat management (UTM) firewall | A UTM device typically combines, in a loosely coupled way, the functions of a stateful inspection firewall with intrusion prevention and antivirus. It may also include additional services and often cloud management. |
| Next-generation firewall (NGFW) | Firewalls have evolved beyond simple packet filtering and stateful inspection. Most companies are deploying next-generation firewalls to block modern threats such as advanced malware and application-layer attacks. |
