Smoothwall is a Linux distribution

Linux distribution

A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...

 designed to be used as an open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 firewall. Designed for ease of use, Smoothwall is configured via a web-based GUI

Gui

Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...

, and requires little or no knowledge of Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 to install or use.

Smoothwall is also a private software company based in the UK that develops firewall and web content filtering software, and which also maintains the SmoothWall open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 project.
Smoothwall began life as SmoothWall GPL, a freely redistributable version, in August 2000, with a proprietary version sold by SmoothWall Ltd from November 2001.