Firewalls have long been a mainstay of corporate security - but when it comes to Web services, they may well provide no security at all, because they can only filter at the packet level, and can't examine the contents of messages. Considering that Web services traffic may account for 25 percent of all enterprise traffic by 2006 according to the ZapThink Web services consulting group, that is a serious problem for any business looking to use Web services.