A virtual private network (VPN) is a private communications network usually used within a company, or by several different companies or organizations, to communicate over a public network. One of the more common uses common uses of VPNs is to facilitate secure telecommuting between a distant office and someone's home. VPN message traffic is carried on public networking infrastructure (e.g. the Internet) using standard (and sometimes insecure) protocols, or over a service provider's network providing VPN service guarded by a well-defined Service Level Agreement (SLA) between the VPN customer and the VPN service provider.  VPNs can be established in a variety of ways, but all of these methods have one thing in common: they all carry a great deal more 'overhead' than conventional network connections. This 'overhead' is almost always associated with the degree of encryption and security used to establish the VPN tunnel through the Internet.

Why does this concern you? Because some over-the-Internet VPN connections are either too slow or have too high a latency factor or are actually blocked by some Internet service providers. Fortunately, there are ways to overcome such obstacles, and this usually takes the form of a hardware-based VPN 'accelerator'.  StarLAN CS offers three different VPN accelerator technologies, one of which is particularly suited to satellite-based broadband connections

Two of the units shown here are SSL VPN accelerators. SSL acceleration is a method of offloading the processor-intensive public key encryption algorithms involved in SSL transactions to a hardware accelerator. Unti lfairly recently, this is a separate card that plugs into a PCI slot in a computer that contains one or more co-processors able to handle much of the SSL processing. The most computationally expensive part of an SSL session is the stage where the SSL server software is required to decrypt the SSL session key ( a symmetric key ) that has been sent to it from the SSL client (usually a web browser that you are using for your remote connection), This is known as the SSL handshake. A hardware SSL accelerator such as the ones shown here offload processing of the SSL handshake while leaving the server software to process the less intense symmetric cryptography of the actual SSL data exchange.

The third unit, from Encore Networks, is especially designed to handle either IPSec or SSL VPNs over high-latency broadband connections that are typical of satellite-based ISPs.