Queuing Networks (QNs) are a widely used performance modeling notation, which has been successfully applied to many kind of systems. Although the wealth of scientific literature on the solution of queuing networks models, there are very few available implementations of these solution techniques. In this paper I will try to describe networks, a free software package for Queuing Network analysis written in GNU Octave. Networks allow users to compute performance measures of Markov chains, single-station queuing systems and product and some non product-form queuing networks models. I present some practical examples showing to how networks can be used for reliability analysis, capacity planning and general systems modeling and evaluation.