Why do companies use virtual private networks (VPNs)? To let remote users access corporate resources securely, of course. Why don't companies use secure peer-to-peer file (P2P) sharing instead?

There are several answers to the second question. One is that, thanks to music sharing through the likes of Kazaa, P2P has gained a bad reputation in the eyes of IT managers. The relevant IP ports for file sharing are typically sewn up tight on firms' internet gateways.

Another answer is the perception that there are no "good" commercial P2P systems - they're all supposedly written by evil file-sharing music pirates. But it looks like P2P is starting to gain a measure of respectability, and may soon be putting on its metaphorical suit and tie.

I've recently been playing around with a program called FolderShare, a beta P2P application that lets you share any folder or file on your Windows PC with anyone you invite into your secure peer group. You can set up a full hierarchy of read/write access

privileges, and all traffic is RSA authenticated and AES encrypted using 256bit keys over a Secure Sockets Layer (SSL) connection.

Users can access files via a client application, or via placeholders on the FolderShare web site (no data is stored there, only links). This FolderShare method obviously doesn't work if all the PCs in the peer group are behind firewalls. However, it is a good corporate citizen; it doesn't leave ports open, and it authenticates clients before initiating any transfers. The developers have obviously tried very hard to establish the system's credentials for the business market.

It's a neat little program, and lots of business uses immediately spring to mind. Apart from the obvious ones, such as synchronisation of files between a worker's home and office systems, it could also be used as a patch distribution system, a collaborative workspace, or even a way of instantly publishing company information to a large number of people.

I've used FolderShare to share large work files with European colleagues and freelance staff, where most email systems would balk at 40MB transfers, and FTP servers are dodgy at the best of times.

Of course, perceived insecurity is still the main bugbear, so FolderShare is likely to be dismissed out of hand by IT managers, unless the whole lot can be centrally managed and locked down.

But as ever, if Microsoft sniffs an opportunity, you can guarantee that it will be in there like the proverbial rat up a drainpipe. And the company already seems to be scuttling in that direction.

In the Advanced Networking Pack for Windows XP, alongside a production-quality IPv6 stack and IPv6 firewall, you will find an IPv6-based Windows Peer-to-Peer service, plus the Teredo NAT traversal client. This wraps up IPv6 packets inside IPv4 packets to allow IPv6 unicast capabilities over the wider internet. Secure P2P transfers are just one possible application of such a technology.

The only application I can find that uses Teredo at the moment is Microsoft's own ThreeDegrees, a consumer file sharing service that's still at the beta stage. Consumer testing is a great way to iron out bugs, but I suspect that consumers are not Microsoft's ultimate target.

Watch out later this year for some other big names launching business-focused P2P applications. You heard it here first.