Computer Security – Definitions

Application-Proxy Gateway Firewall: An advanced firewall that combines lower layer access control with upper layer functionality, and includes a proxy agent that acts as an intermediary between two hosts that wish to communicate with each other.

Boundary Router: A router located at the organization’s boundary with an untrusted external network. In the context of this document, a boundary router is configured to be a packet filter firewall.

Circuit-Level Gateway: A form of [..]

Firewall Planning

The planning phase for choosing and implementing a firewall can begin only after an organization has determined that a firewall is needed to enforce the organization’s security policy. This typically occurs following a risk assessment of the overall system.

A risk assessment includes :

• the identification of threats and vulnerabilities in the information system;
• the potential impact or magnitude of harm that a loss of confidentiality, integrity, or availability would have on the [..]

Firewall policies | IP Addresses and Characteristics

Firewall policies should only permit appropriate source and destination IP addresses to be used. Specific recommendations for IP addresses include:

• Traffic with invalid source or destination addresses should always be blocked, regardless of the firewall location. Examples of relatively common invalid IPv4 addresses are 127.0.0.1 (also known as the localhost address) and 0.0.0.0 (interpreted by some operating systems as a localhost or a broadcast address). These have no legitimate use on [..]