Although Vista's firewall will ship with both in- and outbound filtering capabilities, the latter will be disabled by default. Corporate users, however, can turn on outbound if they wish.
"Inbound filtering is on by default and outbound filtering for applications is configurable by enterprise administrators through Group Policy," said a Microsoft spokesperson.
Microsoft has been promoting Vista's firewall as better than XP's because it's able to stop both incoming attacks and filter outbound traffic. But with it enabled only for incoming data, the end result is a defense identical to Windows XP SP2, which has an incoming-only firewall that's automatically enabled.
Selective outbound blocking has been offered by other firewall providers, including Symantec and ZoneLabs, for years. The tactic is used to stop unauthorized programs from accessing the Internet, and touted as a way to prevent spyware from transmitting stolen data to criminals, even if the spyware gets past other protection and burrows its way onto a hard drive.
Still, Peter Pawlak, an analyst with Kirkland, Wash.-based Directions on Microsoft, believes Microsoft's taken a "reasonable position" to disable the outbound capabilities of the Vista firewall.
"It's bad enough with anti-virus and anti-spyware scanners, which ask you to make decisions based on information that you don't have any idea what it's talking about," said Pawlak. "But I just can't imagine individuals dealing with outbound protocols and ports on their own. The idea of an outbound firewall is pretty darn technically tricky for the average user."
The reason why Microsoft's included outbound filtering in Vista, said Pawlak, is to let enterprises lock down systems when they're outside the corporate perimeter.
"When you're using a laptop, there should be some protection that limits the data that you might send. [Outbound] is really for protecting the information on your laptop."
Pawlak was somewhat dismissive of firewalls that catered to consumers and boasted of filtering outgoing traffic. "Vendors have to come up with some sort of set of what they think should be permissible. If you err on the loose side, how much improvement does that make over no firewall at all?
"And if you start from 'permit nothing,' how many messages are consumers going to have to deal with?"
Microsoft's not totally abandoning consumers on the Vista firewall issue. Inbound filtering, for instance, will be managed much like in Windows XP, said the company's spokesperson.
But if users choose to turn on outbound filtering in Vista, they'll have to rely on "outbound filtering rules that are enabled by default for core Windows services as part of Windows Service Hardening," said the spokesperson.
Windows System Hardening is Microsoft's nomenclature for a Vista feature that restricts critical Windows services from making abnormal changes to the file system, Windows registry, or network, such as the kind of modifications made by malware to install, or once installed, to attack other PCs.
Microsoft also plans to integrate Vista's two-way firewall with Windows Live OneCare, the separate by-subscription security service that launches in June, and which already adds outbound filtering to Windows XP.