Citrix is buying Net6, a privately held maker of SSL (Secure Socket Layer) VPN (Virtual Private Network) technology, for US$50 million cash.

The company will add Net6's SSL Access Gateway and Application Gateway and Voice Office Application Suite to its product line. Citrix plans to use the technology to expand the options for customers who wish to remotely connect to network resources, including applications, data and voice applications.

According to Citrix, the SSL Access Gateway will be sold as a standalone product and in conjunction with the Citrix MetaFrame Access Suite. The company said that the SSL access technology would enhance the existing SmoothRoaming feature that simplifies Citrix sessions over mobile devices.

SSL VPNs are a popular technology for providing remote users with access to network resources such as e-mail, software applications and network file servers. As opposed to VPNs that use IPsec (Internet Protocol security), SSL VPNs are "clientless," meaning they do not require a separate software application to be installed on the remote user's machine. They also rely on the SSL protocol, which is a part of most common Web servers and Web browsers and widely used to secure e-commerce transactions. Interestingly, Net6 claimed that its product range combined the best of both IPsec and SSL.

Citrix already offered an SSL VPN-like gateway with its MetaFrame Secure Access Manager, but that product was only suitable for very large Citrix deployments, said Rob Whiteley, an associate analyst at Forrester Research.

Net6's SSL Access Gateway will give Citrix a way to meet the needs of smaller customers and support remote access for a broader range of applications, such as e-mail, he said.

At the same time, selling the SSL Access Gateway as a standalone product will give Citrix a beachhead in smaller accounts that might be willing to buy more Citrix products later, he added.

Plans for Net6's Application Gateway and Voice Office Application Suite are less clear. Citrix said it wants to build an infrastructure that converges voice, data and applications creating "the ultimate mobile office."

For example, Citrix envisages mobile workers being able to use Citrix and Net6 technology to access hosted applications, Web-based applications and VoIP phone services all from a notebook, desktop or tablet PC, Citrix said.

The technology will eventually help Citrix live up to its new moniker of an "access infrastructure company," Whiteley said.