What is a Virtual Private Network?
A Virtual Private Network (VPN) is an encrypted private network connection that is constructed within a public network infrastructure such as the global Internet. A telecommuter or mobile worker can remotely access the network of the company headquarters from home or anywhere be using a secured internet connection.
VPN connection is used for security issues, broadband services provide capabilities for using Virtual Private Network (VPN) connections to a VPN server, which is typically located at the corporate site.
Through the Internet, a secure tunnel can be built between the PC of the telecommuter and a VPN router at the company headquarters.
Instead of using a dedicated Layer 2 connection such as a leased line, a VPN uses virtual connections called VPN tunnels, which are routed through the Internet from the private network of an organization to the remote site or employee host. Most Cisco products support the latest in VPN technology. It offers secure, reliable connectivity over a shared public network infrastructure such as the Internet.
The figure shows the following steps, which explains the overall transmission in the figure:
1. Host ComputerA on the left sends a packet to the web server, just as it would without a VPN.
2. The network router at the end of the tunnel of computer A encrypts the packet and forwards the packet.
3. A man in the middle copies the packet, but cannot change the packet without being noticed, and cannot read the
contents of the original packet.
4. The network router at the edge of computer B receives the packet, confirms the authenticity of the sender, confirms that the packet has not been changed, and then decrypts the original packet.
The term tunnel generically refers to any protocol’s packet that is sent by encapsulating the packet inside
another packet. The term VPN tunnel implies that the encapsulated packet has been encrypted, whereas
the term tunnel does not imply whether the packet has been encrypted.
VPNs can be built with a variety of devices and for a variety of purposes. There are three primary
reasons for building an Internet-based VPN today: