|DSL vs. Cable Modem Comparison - Security|
When debating the relative merits of cable modem and DSL service, network security might be the most controversial item on the comparison chart. At first glance it appears one clearly wins the security battle over the other, but does this commonly-held opinion stand up to closer scrutiny? (See below)
DSL's Leg Up
A few years ago, conventional wisdom held that DSL service inherently offers better security than cable modem service. Some proponents of this view happened to be DSL providers. One might dismiss such claims as a sales gimmick from over-exuberant DSL networking companies. Yet one finds the same sentiment among some non-commercial organizations as well.
No matter their origins, the claims of superior security for DSL all relate more to a perceived weakness in cable modem security than to any unique advantage DSL might hold.
Cable's Network Neighborhood
Cable modem service uses a shared cable line to provide service to an entire neighborhood. Essentially, all cable customers in the region belong to the same local area network (LAN). Without any security measures in place, anybody in the neighborhood might technically be able to click on their Windows Network Neighborhood icon and actually see the computer names and addresses of their neighbors on the service. If a customer enables file sharing on any drives, neighbors could even download copies of their data!
Although some cable customers encountered this problem in the past, many providers avoid this problem today by bundling security features in the cable modem hardware. In particular, basic network firewall capabilities will prevent files from being viewed or downloaded. Most cable modems today also implement the Data Over Cable Service Interface Specification (DOCSIS). DOCSIS includes support for cable network security features including authentication and packet filtering.
DSL uses dedicated rather than shared cabling, and DSL customers in a given neighborhood do not appear as nodes on a LAN. From this, many have concluded DSL service provides better security. However, this argument is at best an oversimplified one.