Firewalls on computer networks are like river dikes: One bad breach can bring catastrophe. The networks of Citibank (C ), eBay (EBAY ), the Defense Dept., and other organizations are scanned thousands of times a day by hackers. Firewalls fend off 99% of these malicious probes. But eventually, a few get through.
So if a firewall is the only protection for the family jewels, they're in jeopardy. In some cases, "the firewall is rendered irrelevant," says Bruce Schneier, founder of Counterpane Internet Security Inc. Skirting it may be as simple as finding an unprotected network device such as a fax machine or a copier. These are often wired to exchange messages with their manufacturers--and manufacturers can be impersonated. Hackers can also penetrate the network of a target company by wiggling through its undefended Internet links with partners, suppliers, or customers. In short, the burden is on the company to make its entire network bulletproof. Too many hackers these days pack machine guns.
By Roger O. Crockett