Chapter 4 - Networking and the Internet - Section 4.5 - Security - Questions & Exercises - Page 210: 2

A region’s gateway is a router that merely forwards packets (parts of messages) as they pass through. Thus a firewall at the gateway cannot filter traffic by its content but merely by its address information.

A region’s gateway is a router that merely forwards packets (parts of messages) as they pass through. Thus a firewall at the gateway cannot filter traffic by its content but merely by its address information.