Firewall planning | General Recommendations

The following recommendations for firewall planning and implementation will help administrators plan for firewall placement and implement their firewall policies:

• Placement and Deployment
  • Place a packet-filtering firewall at the edge of each discrete network in the organization.[..]

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 [..]

Firewalls | Policies Based on Applications

Most early firewall work involved simply blocking unwanted or suspicious traffic at the network boundary. Inbound application proxies take a different approach—they let traffic destined for a particular server into the network, but capture that traffic in a server that processes it like a port-based firewall.

The application proxy approach provides an additional layer of security for incoming traffic by validating some of the traffic before it reaches the desired [..]