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Virtual Private Network, Its ‘Virtual', Its ‘Private' and it's a ‘Network'. A virtual private network (VPN) provides a secure connection between a sender and a receiver over a public non-secure network such as the Internet. A secure connection is generally associated with private networks. (A private network is a network that is owned, or at least controlled via leased lines, by an organization.). We can define a VPN by the following relationship: VPN = Tunneling + Security + QoS Parameters. This Chapter deals with Advantages of VPNs, Types of VPNs, VPN Architectures, VPN Models, VPN Devices, Technologies and Protocols Used to Enable Remote Access VPNs.

With increasing number of users on the internet, risk of security and probability of vulnerable attacks are increasing day by day. For every user connected to network, security attacks like hacking and cracking are very frequent which leaves enormous amounts of sensitive data at the risk of being altered, lost or misused. This apparently leads to the need for security measures on ports and protocols also search for application security, VPN, IPS, and a firewall support. The hacking and cracking threats and attacks in a network are no longer in control with the existing methods and standard firewalls. The introduction of Next Generation Firewalls leads to improved security over network. This chapter deals with hacking and cracking attacks over network and their countermeasures, also focusing on the changing dynamics of network security with next generation firewalls.