By Rich Loeber
Living in a remote area, a lot of people near us like to leave their doors unlocked for convenience sake. Most of the time this is OK, but occasionally it gets someone into trouble. A recent local incident got me thinking about all the doors that can be used to enter the IBM i and I wanted to take some time to explore this today.
My wife and I live in the middle of the Adirondack Park, a 6 million acre state park in northern New York (think “about the size of Massachusetts”). This area houses a year round population of just over 130,000 souls. As you might imagine, with that population density, security is not a big issue. I know people here who have no idea where their keys are to lock the doors on their house, and are not worried about it. Recently, there was a burglary in the town where my office is located. Someone just walked into the back door of a shop and helped themselves to money in the cash register, then slipped back out without being seen. This got me to thinking about security on the IBM i and how a similar situation might easily exist at many shops where doors are left open for no good reason.
In the “old” days, the only door you had to be concerned about was the computer terminal. These were placed in public places and protected by user profiles and passwords. In order for someone to sneak in, they’d have to be pretty bold and they’d have to know a profile/password pair. Today, the user profile/password continues to be a primary locking mechanism for your system. So, this continues to be your first line of defense.
Keeping your user profile list current is probably one of the most important tasks you can do. Some critical things to remember include enforcing periodic and regular password changes, deactivating and even deleting old profiles for people who are no longer employed there and only providing the level of access permissions that a profile needs. That’s pretty simplistic, but remember that you’re handing out keys to the doors of your system. You want to limit the number of keys in circulation and you don’t want everyone to have a master key. Also, you need to make sure that there are no default passwords active on your system, including passwords for well known third party software packages. The system will watch the doors for you, but if there is no control over the keys, what’s the use?
Assuming that you have your keys under control, then you need to also take a look at all of the doors that are on a modern IBM i server these days. The days of only needing to control terminals is long gone. Today, you need to be concerned about the FTP door, the Telnet door, the Remote Execution door, the ODBC door, the SQL door, the Shared Drive, the Navigator for i door, the file upload/download door and on and on.
For some of these doors, you can easily control access by removing the door altogether. If your shop does not use FTP on a regular basis, then don’t leave the FTP door in place. On most systems that I work on, I find the FTP server up and running by default. It is a simple matter to turn it off with the command:
and to use the Change FTP Attributes (CHGFTPA) command to set the AUTOSTART parameter to *NO so that it doesn’t restart with every IPL. If you occasionally use FTP, you can start and stop it as needed using the STRTCPSVR and ENDTCPSVR commands. With this approach, you not only lock the FTP door, you remove it from your system. If the door isn’t there, it can’t be opened.
Another method for limiting FTP is to only have the FTP server active during normal business hours. It is a simple matter to set up your system scheduler to start FTP in the morning and shut it down at the end of the day. That locks the FTP door for more hours in the day than it is open.
Other servers can be handled this way too. These include the Trivial FTP server, the TCP/IP DDM server and the Remote Execution server to name a few. If your system has these servers active, each one represents another door that can be used to access your system. If you’re not using these server functions, then remove the doors.
The easy way to check on these is to go to the operating system Configure TCP/IP menu (CFGTCP) and run option #20. Check each of the displayed server functions and see how the AUTOSTART parameter is set. If you don’t have any applications using these servers, then remove these doors to your system. The fewer doors that are on your system, the tighter your security.
This only covers some of the doors into your system. Next time around, I’ll address some of the doors that are a little more difficult to keep locked. If you have specific questions about this topic, you can reach me at rich at kisco.com), All email messages will be answered.