Virtual Private Networks (VPNs)

In recent years, the use of virtual private network (VPN) technology has entered into the remote
access landscape. VPNs allow secure connections over public networks—typically making use
of the Internet. Data is encrypted for transport in a virtual tunnel between source and destination,
and its costs are greatly reduced without a substantial decrease in security. As such, a VPN
is a system of these tunnels used to create a logical system of conduits that transport user data.
Although most VPN software is very solid, it’s important to note that most companies bristle
at the thought of using only basic software to secure data. In addition, the processing demands
required by some encryption technologies are high, and many implementations will likely
require newer processors or co-processed implementations. Co-processors offload specific functions
from the main processor; video adapters have used them for years to provide better graphics
output. Encryption can benefit from this coprocessor design as well.
Two common VPN technologies are in use today: IPSec and SSL. The IP Security Protocol
(IPSec) is an encapsulation mechanism that operates at layer 3 of the OSI model. It is useful in
providing a virtual end-to-end connection between points regardless of the technology. In IPSec,
the client is on the network and can use most software and applications. IPSec uses triple-DES
(Data Encryption Standard) in most instances, but this will be replaced in the near future by the
less demanding, and possibly more secure, AES, or Advanced Encryption Standard. Both technologies
encrypt data so it cannot be modified or intercepted en route.
Secure Sockets Layer (SSL) is commonly used to secure web sessions and transactions; however,
it is being used more and more by application emulators and remote access technologies. These
installations provide a screen presence to the remote user—all the processing occurs at the central,
hosting location. As networking evolves, it is quite likely that VPNs and technology independence
will become common, and customers will use any physical connectivity technology—including
Ethernet—to access remote locations.