The specification and development of models for Internet traffic is mainly conducted by measurement-driven performance modeling based upon statistical analysis. Yet, this type of analysis can be a challenging task, due to the complexity and especially, with large sample sizes, the sheer quantity of the data. For this reason, preliminary data examination by graphical means and appropriate visualization techniques can be of great value. In this paper, we present the recent developments of the network traffic analyzer Atheris. Atheris has been designed specifically for measuring network traffic and for the visualization of its inherent properties. As a part of Atheris’ functionality, it performs traffic measurements at the packet layer, data extraction, flow analysis and enables the visual inspection of statistical characteristics.