[no mention of sniffing neighbors and other concerns]

http://www.zdnet.com/zdtv/cybercrime/spyfiles/story/0,3700,2190636,00.html

Cable Modem Security
By Ira Winkler  February 3, 1999

Cable modems and other high speed connections are becoming increasingly
more available-- but what are the security risks? 

Late last year, a Screen Savers viewer asked about cable modem security,
concerned that many computers linked to cable modems are on all of the
time.  The response? Don't worry. This concerns me. 

Before examining why cable modem users are more at risk, here are the
technical differences between regular modems and cable modems. When you
dial into an ISP with a regular modem, your computer is randomly assigned
an Internet address. 

["Here are the technical differences.." This makes it sound like
they are essentially the same. Cable modems and their providers have
several other differences which can affect their security.]

That address equates to the specific modem at the ISP that you dialed
into, and for that session, that is your Internet identity. On the next
session, you will probably have a different address. 

However, when you have a cable modem, your address is always the same. 

People with cable modems frequently leave their connection active 24 hours
a day. While this isn't wrong, it opens a major security risk, leaving
users more vulnerable to a hacker attack. 

[Millions of hosts around the net are a) not on cable modems and
b) have the same IP address all the time. This has little to do with the 
security concerns of owning a cable modem. Ira doesn't even touch on problems
of open networks, unencrypted links, or inherent security problems in the
customer's machines.]