In recent years, Network Security has emerged as one of the most important challenge for many organizations. The enormous proliferation of the Internet and emergence of unified data, voice and multimedia services are responsible for emerging communication models that are essential for successful business activity of any organization. However, the increasing numbers of sophisticated security threats have the potential to significantly impede productivity, disrupt business operations and result in loss of information. Therefore maintaining a secure network remains the top priority for most organizations. The aim of this tutorial is to discuss the major security issues faced by network managers and the solutions currently employed.