At the start of the year I wrote about the benefits of web-based alternatives to the traditional virtual private network (VPN), and how they would use the Secure Sockets Layer (SSL) protocol to handle the necessary encryption.

Since then, it seems, the world has gone SSL mad, and many analysts predict exponential growth, the like of which we've not seen since before the dot-com crash.

In its World SSL VPN Products Market report, analyst firm Frost & Sullivan forecasts sales of just under $90m (£52m) this year, rising to $1bn (£660m) by the end of 2008.

The lion's share of the anticipated demand is likely to come from the US due to recent laws to tighten up security in industries such as finance and healthcare. But SSL is grabbing attention in other countries too, and lots of firms are keen to get on the bandwagon.

Predictably, some of the early pioneers of SSL have been swallowed up, although not always by the buyers you might expect. This is because SSL VPN technology bridges the gap between networking and security, causing both groups of vendors to try to add SSL functionality to their products.

On one side, we find security firms such as Symantec, which recently added SafeWeb to its growing portfolio of acquisitions. On the other side, networking firms specialising in Layer 4 to 7 load balancing switches, a market that has been in the doldrums for some time, are also staking their claims. F5 Networks recently snapped up uRoam - after firewall/VPN specialist NetScreen decided to acquire Neoteris rather than uRoam.

Further rationalisation and acquisitions are inevitable, with companies such as Aventail, Netilla, Whale and others clearly vulnerable. However, the gravy train may not last long because many of the larger networking companies, including Cisco and Nortel, are developing their own SSL tools.

The market is maturing rapidly, and SSL VPN technology looks set to be integrated into a range of products in addition to remote access appliances.

This may be good news for customers, but there are one or two dissenting voices.

Some analysts warn that the simplicity of web-based remote network access makes it more vulnerable to hackers and other intruders. They argue that the extra security necessary at both the client and the network side of the SSL VPN link makes the solution just as complex to manage as a traditional IPSec VPN.

Current SSL-based security appliances are also far more expensive than VPN gateways, which could lose the custom of smaller firms where the appliances might be of most benefit. And for branch office deployment, IPSec VPNs are actually easier. Added to which the IPSec VPN camp is fighting back with a new version of the Internet Key Exchange (IKEv2) protocol.

Originally planned to reduce possible vulnerabilities, IKEv2 will be a lot simpler than the current technology, and will ease key exchange management. But, it is currently only a draft proposal and may take a couple more years to get to market. By then, SSL remote access might be the only game in town.