Network Security

Network security has become an important topic in system administration as computing services have moved away from host-centric models to network-distributed models. While host security issues still exist, it is now uncommon for there to be one (or even a few) central computers that provide all computing services to a user community. Instead a group of hosts tend to provide specialized services, and users access those services from their own computers, which are in many cases as powerful and network-captable as the so-called "server" hosts.

Overall the trend is towards more computers that are more powerful and that have more network interactions. The greater number of hosts combined with the greater networking capabilities of each host means that security management of an entire network has become quite complex and difficult, especially when the increasing use of networked services has brought with it a huge number of potential security vulnerabilities.

In general, network security has a number of practical components:

• Inventorying network hosts, to understand the locations and types of hosts in your network
• Monitoring of network traffic, to find anomalous traffic and other indications of security issues
• Appropriate filtering to prevent exposure of vulnerable services or protect data security
• Applying host security measures to prevent (or stop) exploitation of hosts and reduce overall vulnerability exposure

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