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Overview
Even 20 and more years ago companies were connecting region and country offices with data lines. They had to lease these telecommunication lines from the local telecom (telco) companies for a lot of money and therefore only big companies could afford it.
When the Internet became bigger and bigger people were thinking about using this free - at least in comparison to their costs for leasing data lines - network for building a company network. But it should be still a private network, the public and other companies should not have access to it.
This was achieved by building a protected and encrypted connection between two end points identified by an IP number. And hence the virtual private network VPN was born.
While there a various ways to actually implement a VPN the essense is that data is encrypted and that a direct connection, a VPN tunnel is established between two end points. In practise, end points are either identified by preshared keys or by SSL certificates. This is secure as long as security policy - that is the preshared key or the SSL certificates are not compromised.
VPN connecting two offices
A fixed link VPN is a VPN connection between two or more locations identified by a global IP number.. Such a permanent VPN link is normally implemented using VPN routers. The VPN router needs to be configured once and there is little or no maintenance required once the connection is set up.
Compared to a normal router a VPN router has additional IPSEC software build it. (IPSEC is an extension to the IP protocal and the lowest level protocol which can be used to implement a VPN). If no VPN routers are available a VPN can be build using special software.
Sales staff accessing the office via VPN
In the old times, if you wanted to give sales staff in a regional office access to some program located on the company's mainframe you had to provide dial-up access via a modem. Besides being slow you had to bear the telephone charges and telco companies would charge depending on the distance. Using a VPN sales staff can connect to the company network using their existing Internet connection. Once they are connected to the Internet they start a small program, the VPN Client and this software will talk to the company's VPN router and establish a VPN tunnel to the office. This is easy and cheap.
Benefits of a VPN The main benefits of implementing a VPN:
- A VPN is a very cost effective way to build a private and secure connection between two or more locations. Typically you only pay the costs to access the internet i.e. the costs for your local provider.
- Faster communications (because you can afford higher bandwidth connections to the Internet at each office than you could for direct links, and VPN technology is encrypted or tunnelled at the hardware level and not at the software level increasing efficiency and speed)
- Improved employee productivity as users can connect to the network whenever and wherever. This also saves time as email file attachment requests will become unnecessary.
- As IT and networking technology are becoming more sophisticated (= more complicated) it is difficult for smaller companies to keep up-to-date. Having implemented a VPN it is possible to outsource IP support work. The external provider can directly access the system and perform system checks and maintenance work directly on the target system. This is a Win-Win situation because the customer gets a better response time and the support company saves travel time.
Scalability of a VPN
As your company grows you might want to expand your network. A VPN uses the Internet for connecting locations and as this is already in place it is cheap to add locations to your VPN. This means even small companies can afford to add additional locations or remote users.
Applications that can run through a VPN
VPNs are not just for e-mail and accessing Intranets, VPNs in general will cope with any application you currently use on your network. Fast hardware-based VPN's carry voice,video and multi media traffic.
Network browsing and file shares
Access to file shares and drive mappings are all possible. It needs to be set up properly to prevent that non-authorized people can use these function.
How secure is a VPN? Security depends on the quality of data encryption. While the Data Encryption Standard (DES) is not very strong 3-DES (triple -DES) has never been broken. Most routers use the IPSEC (IP Security) standard, an extension to the IP protocol (RFC2401). Using IPSEC the IP header containing source and destination addresses is encrypted as well. VPNs are secure if implemented and managed in a sensible way. The biggest danger comes from sloppy handling of preshared keys or certificates.
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