Understanding network security

This chapter describes several security solutions and discusses how these security solutions can be used to address the challenges you may encounter. Firewalls remain the foundation of network security technologies. There are a number of options, types, and technologies associated with selecting, implementing, and maintaining the firewalls in a network. There are also a number of factors that help determine the proper solution to meet business requirements. A firewall is a system that is designed l to protect a computer or a computer network from network‐based attacks. A firewall does this by filtering the data packets traversing the network. There are numerous variations on this model, but ultimately a firewall protects hosts on one network from hosts on another network. These network connections may be referenced using different labels: internal and external, clean and dirty, secure and unsecure, local and remote, and so on. They all refer to the same model, but occasionally may need translation into familiar terminology. Any discussion about network security requires a discussion and understanding of the Open Systems Interconnect (OSI) reference model. The OSI model is a conceptual model, created by the International Organization for Standardization (ISO) in 1978 and revised in 1984, to describe a network architecture that allows data to be passed between computer systems. While never fully utilized as the model for a protocol, the OSI model is the standard for discussing how networking works.