Firewalls

Stateless firewalls (sometimes called packet filters)

filter every packet based on data such as the source and destination IP and port, the protocol, and other information that can be gleaned from the packet’s headers. They are the most basic type of firewall

Stateful firewalls (sometimes called dynamic packet filters)

pay attention to the state of traffic between systems. They can make a decision about a conversation and allow it to continue once it has been approved, rather than reviewing every packet. They track this information in a state table, and use the information they gather to allow them to see entire traffic flows instead of each packet, providing them with more context to make security decisions

Next-generation firewall (NGFW)

devices are far more than simple firewalls. The general term has been used to describe network security devices that include a range of capabilities such as deep packet inspection, IDS/IPS functionality, antivirus and antimalware, and other functions

Unified threat management (UTM)

devices frequently include firewall, IDS/IPS, anti-malware, URL and email filtering and security, data loss prevention, VPN, and security monitoring and analysis capabilities

Web application firewalls (WAFs)

are security devices that are designed to intercept, analyze, and apply rules to web traffic, including tools such as database queries, APIs, and other web application tools