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Auditing is the process of tracking users and their actions on the network. Learning the concepts of proper auditing will be a valuable asset.

The types of activities that can be audited include the following:

  • Network logons and logoffs

  • File access

  • Printer access

  • Remote access services

  • Network services

  • Application usage

Auditing should be built around security goals and policies. Effective planning and well-defined structure must be a part of an audit policy for it to work properly. You should not monitor everything; otherwise, you will stress system resources, fill up the hard drive and log files, and never be able to weed through the mounds of data that has accumulated. Therefore, monitor what is really important. If you aren't sure what is important, many recommendations can be found on the Internet. Microsoft has an area devoted to securing its operating systems that also contains auditing information. In the end, auditing should be a policy determined to meet the specific needs of the company.

Here are the steps to take when initiating an audit policy:

  1. Identify potential resources at risk within your networking environment. This may include files and services that should be protected from unauthorized access.

  2. After the resources are identified, set up the actual audit policy. Each operating system will have its own tools for tracking and logging access. If the policy stipulates auditing large amounts of data, be sure that the hardware can handle the load. Auditing can easily add 20% to 30% additional load onto a server.

  3. Make time to view the log files generated after auditing is turned on. If your network is compromised and the intrusion was recorded in your log files six months ago, what good is that? If possible, import these files into a database and view the data graphically or query for abnormalities.

Along with auditing, establish a baseline of normal activity. Then the network behavior can be monitored against the baseline. As you begin to understand the patterns of your users and the network, it will be much easier to identify odd or suspicious behaviors.

System Scanning

Scanning is a process used to probe ports. Scanning programs keep track of those ports that are receptive listeners, and they also analyze weaknesses. Many vulnerability scanners are available for download on the Internet. These tools can be extremely useful in determining how vulnerable your network is. However, you should not try these tools without an administrator's permission. The following list names some of the most commonly used tools:

  • Nessus—Provides a free, powerful, up-to-date and easy-to-use remote security scanner. Nessus is fast, reliable and has a modular architecture that allows you to fit it to your needs.

  • NetRecon—Helps organizations secure their Windows NT networks by scanning systems and services on the network and simulating intrusion or attack scenarios.

  • Nmap—Nmap (network mapper) is a Linux open-source utility for network exploration or security auditing. It was designed to scan large networks but also works fine on single hosts.

  • SAFEsuite—This suite can scan a TCP/IP network, look for problems in a Web server, and test both proxy-based and packet filter–based firewalls. It can be used on Windows NT, Solaris, and Linux platforms.

  • Security Administrator's Tool for Analyzing Networks (SATAN)—An administrative tool that recognizes several common security problems and for each one found offers a tutorial that explains the problem, what its impact could be, and how to correct it.

  • Security Administrator's Integrated Network Tool (SAINT)—An enhanced version of SATAN, SAINT is used for evaluating the security of networks.

  • Tiger Tools TigerSuite—Includes modules for remote scanning, service detection, and penetration testing. Also, tools are available for the PocketPC and Windows CE handhelds.

Although network administrators can find these tools very useful, there can be serious consequences for using them in a malicious way. These days, the members of the Board of Directors can be held responsible should data be compromised. For example, you work for a financial institution. You do business with other financial institutions. The help desk employees use PCAnywhere to help users resolve issues. Last week you hired a new technician. Yesterday, you found out that one of the companies you do business with has called about some odd behavior on its network. You find out that the new technician has been running a utility and scanning all the networks of the clients he has dialed into since he started. You, your company, and the Board of Directors can be held responsible for his actions.

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