vb.net create barcode image VPN server in Visual C#.NET

Creator PDF 417 in Visual C#.NET VPN server

VPNs provide a solution that allows a department s LAN to be physically connected to the organization s internetwork but technically shielded and protected by a VPN

server. In this configuration, the network physically connects the shielded depart ment network to the rest of the corporation, but by using a VPN server as a gateway to the shielded department s network resources, the network administrator can ensure that only users on the organization s internetwork who have appropriate credentials (based on a need-to-know policy within the company) can establish a VPN connection with the VPN server and gain access to the protected resources of the department. Additionally, all communication between the remote workstation and the VPN server can be encrypted for data confidentiality. By placing the VPN server as a gateway to the department, users who do not have proper credentials cannot view the department LAN and users who do have proper access permission can view the department LAN with complete privacy and security over the com pany intranet.

When deploying a remote networking solution, some basic features need to be addressed to provide privacy, data integrity, and connection management for facili tating controlled access to the organization s resources and information. Providing all these features is a complex process and requires the cooperative effort of several technologies. The solution must allow roaming or remote clients to connect to LAN resources, and it must allow remote offices to connect to each other to share resources and information (site-to-site connections). To ensure the privacy and integrity of data as it traverses the Internet, encryption, authentication, and authori zation technologies are required as well. The same requirements apply in the case of sensitive data traversing an organization s internetwork. To support all these requirements, a VPN solution should provide all of the following:

and grant VPN access to authorized users only. It must also provide audit and accounting records to show who connected and for how long.

on the intranet and ensure that addresses used on the intranet are kept pri vate. Also, certain information to allow the client to access resources on the protected network needs to be provided. For example, routing information, resource name resolution, and quarantine security can be provided as well as security filters to ensure the protection of internal data from unauthorized use.

unreadable to anyone but the VPN client and server. To make this happen, encryption technology must be used between the client and the VPN server.

some sort of encryption-key mechanism to create the session tunnel. The solution must generate and refresh encryption keys for the encrypted data on a mutually agreed upon periodic basis so that security and privacy can be maintained.

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An Internet VPN solution based on PPTP or L2TP/IPSec meets all these basic requirements and takes advantage of the broad availability of the Internet. Other solutions, including IPSec tunnel mode (IPSec TM), meet only some of these requirements, but they remain useful for specific situations. The remainder of this chapter discusses VPN concepts, protocols, and components in greater detail.

Tunneling is a method of using an intermediate network infrastructure to transfer data for one network over another network while maintaining privacy and control over the original data. The data to be transferred (the payload) can be the frames (or packets) of another protocol. Instead of sending a frame as the originating node produces it, the tunneling protocol encapsulates the frame in an additional header. The additional header provides routing information so that the encapsulated payload can traverse the intermediate network. The encapsulated packets are then routed between tunnel endpoints over the internetwork. The logical path through which the encapsulated packets travel through the internetwork is known as a tunnel. Once the encapsulated frames reach their destination on the internetwork, the frame is decapsulated and forwarded to its final destination. Tunneling includes this entire process (encapsulation, transmis sion, and decapsulation of packets). Figure 2-5 shows tunneling.