A firewall environment is
|“||a collection of systems at a point on a network that together constitute a firewall implementation. A firewall environment could consist of one device or many devices such as several firewalls, intrusion detection systems, and proxy servers.||”|
- ↑ NIST, Guidelines on Firewalls and Firewall Policy (Sept. 2009) (NIST Special Publication 800-41, Rev. 1) (full-text).