Stateful-Inspection Firewalls; Packet-Filtering Firewall - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

ProCurve Secure Router OS Firewall—Protecting the Internal, Trusted Network
Overview
4-4
A router firewall protects your network entry points, stopping threats
before they get through the router.
An integrated firewall is less expensive.
A firewall integrated on a router allows an organization to enforce a
standard security policy for all hosts.

Stateful-Inspection Firewalls

A stateful-inspection firewall examines packet content at a number of OSI
Layers. It combines aspects of:
a packet-filtering firewall
a circuit-level gateway
an application-level gateway

Packet-Filtering Firewall

A packet-filtering firewall is a router or computer that runs firewall software
that has been configured to screen incoming and outgoing packets. Operating
at the Network Layer (Layer 3) of the OSI model, a packet-filtering firewall
accepts or denies packets based on information contained in the packet's TCP
and IP headers. (See Figure 4-1.)
You must establish the rules against which a packet-filtering firewall compares
the full association of the packets. A packet's full association includes the
following information:
source address
destination address
application or protocol
source port number
destination port number
When you define rules, you specify which packets should be allowed and
which should be discarded. For the Secure Router OS firewall, these rules are
called access control lists (ACLs) and access control policies (ACPs).