Turtle Firewall uses a conservative security approach. Connections are by default set as initially forbidden until the user or administrator defines the rule set (or policy) for which connections are to be allowed. Two policies must be defined for each connection, one for the outgoing packets and the other for the incoming packets. A list of active rules can be viewed at any time. The process of defining connection policies is straightforward. Turtle Firewall employs a graphical user interface (GUI) known as Webmin that is suitable for novices as well as for advanced users. It is also possible to edit the code directly in order to define the connection policies.
Turtle Firewall was written by Andrea Frigido of Frisoft, and is available under the GNU Public License (GPL).