Page 811 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

gateway firewalls are considered second-generation firewalls because
they represent a modification of the application-level gateway firewall

concept.

Stateful Inspection Firewalls Stateful inspection firewalls (also
known as dynamic packet filtering firewalls) evaluate the state or the
context of network traffic. By examining source and destination
addresses, application usage, source of origin, and relationship
between current packets and the previous packets of the same session,

stateful inspection firewalls are able to grant a broader range of access
for authorized users and activities and actively watch for and block
unauthorized users and activities. Stateful inspection firewalls
generally operate more efficiently than application-level gateway
firewalls. They are known as third-generation firewalls, and they
operate at the Network and Transport layers (layers 3 and 4) of the
OSI model.

Deep Packet Inspection Firewalls Deep packet inspection (DPI)
firewalls is a filtering mechanism that operates typically at the
application layer in order to filter the payload contents of a
communication rather than only on the header values. DPI can also be
known as complete packet inspection and information extraction (IX).
DPI filtering is able to block domain names, malware, spam, or other
identifiable elements in the payload of a communication. DPI is often

integrated with application layer firewalls and/or stateful inspection
firewalls.

Next-Gen Firewalls A next-gen firewall is a multifunction device
(MFD) composed of several security features in addition to a firewall;
integrated components can include an IDS, an intrusion prevention
system (IPS), a TLS/SSL proxy, web filtering, QoS management,
bandwidth throttling, NATing, VPN anchoring, and antivirus.

Multihomed Firewalls

Some firewall systems have more than one interface. For instance, a
multihomed firewall must have at least two interfaces to filter traffic
(they’re also known as dual-homed firewalls). All multihomed
firewalls should have IP forwarding, which automatically sends traffic