Network/Internet Security

By Rich Loeber

When your system is connected to a network, you cannot always guarantee the integrity of the person at the far end of a network connection. If your system is connected to the Internet, ethics go out the window altogether. You have to assume that the person at the far end is a bad guy, then proceed from there. With this tip, we'll outline an approach to this problem that may help you to focus in on how to deal with the bad guys wherever they may be.

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 IBM i server in the office recently, 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 SafeNet/i 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:

• System security - including your system level use of user profiles and regularly rotated passwords. For most IBM i shops, this will be your last line of defense, so plan it well. Consider using longer passwords or pass phases that are now supported by the IBM i OS.
• Network security - this commonly involves implementation of a firewall between your network and the Internet but can also include services available from your ISP. On the IBM i there are also things that can be done at the IBM i OS server level via exit programs that can address network security issues.
• Application security - your applications should be designed to integrate with your security policies. Application software can easily be misused and abused and your applications should be designed with this in mind, especially those applications that are open to network and Internet users.
• Transmission security - when you use an uncontrolled network like the Internet, your data will be open to anyone while it is in transit from one place to another. To protect your data, you need to consider encryption techniques and the use of Secure Sockets Layer (SSL) on your IBM i along with encryption. Encryption should be required for all 5250 terminal connections.

In your plan for Network and Internet security, you need to have a plan for each of these layers of control in order to safeguard your system. And, even then, a bully or a sneak might still get past you, so watch out.

If you have questions about details of this tip, feel free to contact me directly by email: rich at kisco.com.