Dia is a program for creating diagrams of all kinds. The current version can do UML class diagrams, Entity-Relationship modeling, network diagrams, and much more. The engine is very flexible and dynamically loads diagram-types from disk. It stores diagrams in an XML format, but can read and write a number of different formats.
Inkscape is a drawing tool with capabilities similar to Illustrator, Freehand, and CorelDraw that uses the W3C standard scalable vector graphics format (SVG). The supported SVG features include basic shapes, paths, text, markers, clones, alpha blending, transforms, gradients, and grouping. In addition, it supports Creative Commons meta-data, node-editing, layers, complex path operations, text-on-path, and SVG XML editing. It also imports several formats like EPS, Postscript, JPEG, PNG, BMP, and TIFF and exports PNG as well as multiple vector-based formats.
DiaCanvas is a generalized version of the drawing canvas used by DIA. It extends some features used by DIA and adds new ones, while preserving as many of the original features as possible. This project is no longer actively maintained. It is suggested that you try DiaCanvas2 instead.
IPTEditor intends to ease the task of managing/editing iptables rules. It presents an intuitive graphical interface that organizes iptables tables as tabs of a notebook, each of which, in turn, organizes their chains in notebooks tabs. Each rules tab contains a list made up of rows (rules) or item columns ordered according to their occurrence. The items in the rows can be edited by appropriate forms, such as through dialogs for targets and criteria (modules), edit fields for network addresses, and selection boxes for actions and protocols, among others.