Internet bad guys generally fall into two categories, sneaks and bullies. The bullies you can probably identify easiest, they are the ones who go after your system with active attacks. They will try to break into your system trying just about everything in the book. On our test System i5 server (formerly iSeries), we had a bully come by who tried to log on using over 700 different user profiles in a period of 5 minutes. Each logon attempt was met by our exit point software and tossed out right at the point of entry with a security warning message to our security officer for each try. The user profiles were all different and all "typical" of what you might expect to see in just about any shop in the country. When a bully comes after you, he does it with brute force. They can try to spoof your system, guess your passwords, deny others from using your system by keeping it overly busy dealing with their break-in attempt and much more.
The sneaks are a lot more passive. A sneak will sit back and monitor network traffic to your system and try to uncover secret information that will then give them what they need to gain access to your system "normally." Sneaks are very hard to identify and the have insidious tools at their disposal to get the information they want. This can even include Trojan horses that gather the information for them. Since sneaks are so hard to identify, you should plan your security strategy assuming that someone is always watching your system.
To guard your system against both sneaks and bullies, you need to think about how to layer your system defenses to guard against anything and anyone. If your system is connected to the Internet, you must assume that a sneak or a bully is going to attempt to gain access and plan accordingly. The best defense is always a good offense and you should consider the various layers of your system and have a plan to deal with intruders at every level. This layered approach will help you develop a good defense. The layers you should give consideration to include:
In your plan for network and Internet security, you need to have a plan for each of these layers of control in order to guarantee your system. And, even then, a bully or a sneak might still get past you, so watch out!
If you have specific questions about this topic, e-mail me at firstname.lastname@example.org. All e-mail messages will be answered.
About the author: Rich Loeber is president of Kisco Information Systems Inc. in Saranac Lake, N.Y. The company is a provider of various security products for the iSeries market.