Free Firewall lab: Build zone rules, NAT and aliases, then prove what traffic is allowed.

A firewall console in your browser: interfaces, aliases, NAT and rule editors for a sample company network with a DMZ, and a policy lookup that shows the decision and the rule that matched for any flow you enter. Includes the network diagram editor.

Free, no login, nothing to install. Your work stays in this browser.

What you can do

• Write allow and deny rules per interface and zone
• Set up aliases and NAT for published services
• Look up any flow and see which rule decided it
• Sketch the DMZ in the built-in diagram editor

Graded, AI-assisted versions live in network security and firewall courses.