This article (question) was written (answered) by Jerry Carson, in the "Ask the Expert" column. This article appeared in the April 2000 WYSIWYG newsletter.
Cable Modem Security
by Jerry Carson
Q: Dear Ask The Expert,
I have a cable modem connection to the Internet. I've heard that security is less than other methods, including DSL. Is the security issue real with cable systems? Also, is there anything that can be done to improve things?
A: Dear Questioner,
First the bad news. Yes, cable modems can be less secure than many other types of modems. This is due to the fact that you are sharing your cable access with everyone else on your segment. Your segment may be a block, 2 blocks, or several miles of access. Everyone on your segment can see what you are sending and receiving.
Now the good news. Most people have no idea how to look at information going to or coming from your computer, and many cable companies are now implementing encryption to secure your private data.
There is another small security problem that many early cable and DSL users encountered. Early cable and DSL users were assigned an IP address that didn't change. This was convenient for the ISP but it means that anyone who wanted access to your machine just needed to find out your IP address and then they could target your machine specifically. Most ISP (cable and DSL) now use an assigned IP address which is only good for one session. However, many DSL and cable users leave their systems up 24/7 (I know I do) so one session can last a very long time.
This brings us to what I consider the largest "security" problem. Being connected to the Internet for that long means you have more of a chance of being noticed by "the bad guys". Unless you have something a hacker wants, odds are he (or she) won't bother your system. However, as witnessed by the recent DOS attacks, a computer connected to the Internet can be used as tool for further mischief.
There are a few things you can do. 1) ALWAYS back-up your system. That way if something does happen, you're covered. 2) Always scan downloaded files for viruses. 3) NEVER open an executable that someone has emailed to you unless you know exactly what is in it. Even then, see rule #2. 4) You can install a firewall. A firewall is a software program that only allows certain types of Internet messages to come into your machine. I have a firewall that only allows answers to messages that I send out. In other words, no one can "talk" to my machine unless I "talk" to them first. Firewalls do have a few drawbacks: They're expensive and complicated. If you don't set them up correctly you may find you can't access the Internet at all. I don't think firewalls are ready for the average user. If, however, you have a business and can afford it, I recommend buying a firewall and getting a knowledgeable professional to install it.
End of Article