A virtual private network, or VPN as it is commonly known, is a network that uses a public telecommunication infrastructure to provide faraway offices or individual users with secure access to the network of their organization. A virtual private network can be compared with a system of owned or leased lines. These leased lines can be used by one organization only. A VPN is used to provide the organization with the same services but at a lower cost. A VPN can be described as one or more wide area network (WAN) links over a shared public network. A network service provider usually provides this link. Secure VPN technologies may be used to enhance the security of the private link. One such security measure is the use of SSL VPN for tunneling specific protocols,

Secure socket layer virtual private network or SSL VPN is a Virtual Private Network, which extends as connection over the public Internet, enabling far away users to access corporate resources securely. SSL is an application level transport protocol that transmits data over a standard TCP port. An SSL VPN can deliver access to a distant network. Any client who has a network connection can make use of SSL VPN without the need for any additional client software. Also, Internet users do not need to remember the names or IP addresses of machines on the network. All resources can be made available to users in the form of bookmarks.

SSL VPN has several other advantages. The most important one is that many remote users can access a network from anywhere in the world. It doesn't need a dedicated laptop or remote VPN site to access the network. A secure extranet can be set up by the company for its business partners and customers. A SSL VPN can provide fine-grained application level filtering. Most SSL VPNs can traverse firewalls and NATs.

SSL uses a cryptographic system. It uses two keys to encrypt data - a public key and a private or secret key. Typically, everyone would know the public key but only the recipient of the message would be aware of the private key. The two most common web browsers, Netscape Navigator and Internet Explorer, support SSL. Most Web sites use a SSL protocol to obtain confidential user information.