Most network security incidents are avoided if professional security assessment is done and simple steps to secure your systems are taken. Network security is a very general term that encompasses many different areas including internet firewalls, user permissions intrusion detection/prevention systems as well as physical security of equipment and media where data is stored. Realistically, there is no such thing as an unbreakable system. The goal of network security is to make penetration of the network not worth the effort. Let professionals make this judgment for you, and provide the right recommendations, as well as implement the policy.