Guarddog

Guarddog is a utility for configuring firewalls on Linux systems that caters to both novice and intermediate users who are not experts in TCP/IP networking and security, as well as those who prefer not to deal with cryptic shell scripts and ipchains/iptables parameters.

One of the standout features of Guarddog is the easy-to-use, goal-oriented graphical user interface that lets you specify what the firewall should do without having to explain all the details of how it should be done. Additionally, Guarddog is application protocol-based, meaning you don't need to understand the ins and outs of IP packets or ports as the tool takes care of this for you. This also reduces the likelihood of configuration errors that may lead to security holes.

Guarddog lets you maintain and modify the firewall in place, unlike other tools that generate the firewall once and forget about it. It also allows you to divide hosts/networks into zones and implement different security policies for each.

The tool supports numerous network protocols such as FTP, HTTP, HTTPS, SSH, and many others that can be entered in directly if not included on the list. Guarddog supports router configurations and runs on KDE 2 or 3, and Linux 2.2, 2.4 and 2.6 series kernels. It also supports advanced Linux 2.4+ iptables features such as connection tracking and rate-limited logging.

Moreover, Guarddog uses a fail-safe design philosophy where what is not explicitly allowed is denied, thus ensuring security. It is well-documented with tutorials and reference material and is licensed under the GNU General Public License, making it free for use. You can also import or export firewall scripts for use on machines other than the current one. Finally, Guarddog supports DHCP configuration.