That leaves you safe, but it's a bummer if you enjoy the speed and convenience of using cable to surf the Web. If cable access has an Achilles heel, it's security. You wouldn't want someone to walk into your house and shuffle through your private papers or take a peek at confidential company information you take home. A cable modem can be like leaving your front door open when you're not home, inviting trouble. People who connect by a phone through dial-up service are not immune, but there's a difference.
Computers talk to each other on the Internet using a series of numbers called Internet protocol.
Dial-up numbers change each time someone connects, offering a bit of security, though not total protection. Many cable modem users stay on the Net constantly and have fixed addresses, making them a more inviting target. Unless you take precautions, you're vulnerable to an attack that can range from a minor nuisance to loss of data. The problem can be caused by your cable modem service provider not securing its networks or by an insecure PC in your home. When you connect to the Internet with a cable modem, you are joining a LAN that usually extends through your neighborhood.