Chapter 9. VPN
This chapter describes the Virtual Private Network (VPN) functionality in NetDefendOS.
• Overview, page 337
• VPN Quick Start, page 341
• IPsec Components, page 351
• IPsec Tunnels, page 365
• PPTP/L2TP, page 383
• CA Server Access, page 392
• VPN Troubleshooting, page 395
9.1. Overview
9.1.1. VPN Usage
The Internet is increasingly used as a means to connect together computers since it offers efficient
and inexpensive communication. The requirement therefore exists for data to traverse the Internet to
its intended recipient without another party being able to read or alter it.
It is equally important that the recipient can verify that no one is falsifying data, in other words,
pretending to be someone else. Virtual Private Networks (VPNs) meet this need, providing a highly
cost effective means of establishing secure links between two co-operating computers so that data
can be exchanged in a secure manner.
VPN allows the setting up of a tunnel between two devices known as tunnel endpoints. All data
flowing through the tunnel is then secure. The mechanism that provides tunnel security is
encryption.
There are two common scenarios where VPN is used:
1. LAN to LAN connection - Where two internal networks need to be connected together over
the Internet. In this case, each network is protected by an individual NetDefend Firewall and
the VPN tunnel is set up between them.
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