Foundation Topics Network Security Policies

IP networks are susceptible to unsecured intruders using a number of different methods. Through the campus, by dialup, and through the Internet, an intruder can view IP data and attack vulnerable network devices.

IP networks must provide network security for the following reasons:

• Inherent technology weaknesses—All network devices and operating systems have inherent vulnerabilities.

• Configuration weaknesses—Common configuration mistakes can be exploited to open up weaknesses.

• Network policy—The lack of a network policy can lead to vulnerabilities, such as password security.

• Outside/inside intruders—Internal and external people always want to exploit network resources and retrieve sensitive data.

Every IP network architecture should be based on a sound security policy designed to address all these weaknesses and threats. Every network should have a sound security policy before allowing remote access, for example. Network vulnerabilities must be constantly monitored, found, and addressed because they define points in the network that are potential security weak points (or loopholes) that can be exploited by intruders or hackers.

Technologies, such as TCP/IP, which is an open and defined standard, allow intruders to devise programs to send IP packets looking for responses and act on them. Countermeasures can be designed and deployed to secure and protect a network.

Intruders are typically individuals who have a broad skill set. Intruders can be skilled in coding programs in Java, UNIX, DOS, C, and C++. Their knowledge of TCP/IP can be exceptional, and they can be very experienced when using the Internet and searching for security loopholes. Sometimes, the biggest security threat comes from within an organization from disgruntled former employees, in particular, who would have access to usernames and passwords.

An intruder's motivation can be based on a number of reasons that make any network a possible target:

• Cyber terrorism

• Challenge to gain prestige or notoriety

• Curiosity, to gain experience, or to learn the tools of trade

Countermeasures against vulnerabilities attacks ensure that a policy, procedure, or specific technology is implemented so that networks are not exploited.

The ever-changing nature of attacks is another major challenge facing network administrators. Intruders today are well organized and trained, and Internet sites are easy targets and offer low risk to intruders. The tools used by intruders (see the section, "Vulnerabilities, Attacks, and Common Exploits," in this chapter) are increasingly sophisticated, easy to use, and designed for large-scale attacks.

Now that you are aware of some of the reasons a network must have a sound security policy and the reason intruders (hackers) want to exploit a poorly designed network, consider some of the standards bodies that are designed to help network administrators.

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