User manual

Virtual Private Networking
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5. Virtual Private Networking
Virtual Private Networking (VPN) enables two or more locations to communicate securely
and effectively, usually across a public network (e.g. the Internet) and has the following
key traits:
• Privacy - no one else can see what you are communicating
• Authentication - you know who you are communicating with
• Integrity - no one else can tamper with your messages/data
Using VPN, you can access the office network securely across the Internet using Point-
to-Point Tunneling Protocol (PPTP), IPSec or L2TP. If you take your portable computer
on a business trip, you can dial a local number to connect to your Internet access
provider and then create a second connection (called a tunnel) into your office network
across the Internet and have the same access to your corporate network as if you were
connected directly from your office. Similarly, telecommuters can also set up a VPN
tunnel over their cable modem or DSL links to their local ISP.
VPN technology can also be deployed as a low cost way of securely linking two or more
networks, such as a headquarters LAN to the branch office(s). IPSec is generally the
most suitable choice in this scenario.
With the SG unit you can establish a VPN tunnel over the Internet using either PPTP,
IPSec or L2TP. IPSec provides enterprise-grade security, and is generally used for
connecting two or more networks, such as a branch office to a head office.
PPTP’s strength is its ease of configuration and integration into existing Microsoft
infrastructure. It is generally used for connecting single remote Windows clients.
L2TP combines elements of IPSec and PPTP. It is generally used as a relatively easy to
configure way to bolster a PPTP-style connection from a remote Windows XP client with
IPSec security.
This chapter details how to configure the L2TP and PPTP servers and clients, how to
configure a remote client to connect, how to establish an IPSec tunnel, and also provides
an overview of L2TP VPN tunneling.