Security appliance
# Security appliance

A security appliance is any form of server appliance that is designed to protect computer networks from unwanted traffic.

## Types of security appliances

* Active devices block unwanted traffic. Examples of such devices are firewalls, anti virus scanning devices, and content filtering devices.
* Passive devices detect and report on unwanted traffic, such as intrusion detection appliances.
* Preventative devices scan networks and identify potential security problems (such as penetration testing and vulnerability assessment appliances).
* Unified Threat Management (UTM) appliances combine features together into one system, such as some firewalls, content filtering, web caching etc.
