The main types of network security devices include firewalls, intrusion protection systems (IPS), unified threat management (UTM) systems, network access control (NAC), email security gateways, web application firewalls (WAF), and VPN gateways. What Are Network Security Devices? Network security. Explore essential security devices in networking with this beginner's guide, covering firewalls, VPNs, IDS, IPS, and more. These devices act as barriers between the internal network and potential threats from the outside world.