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ZyWALL USG 100/200 Series User’s Guide
351
CHAPTER 20
IPSec VPN
20.1 IPSec VPN Overview
A virtual private network (VPN) provides secure communications between sites without the
expense of leased site-to-site lines. A secure VPN is a combination of tunneling, encryption,
authentication, access control and auditing. It is used to transport traffic over the Internet or
any insecure network that uses TCP/IP for communication.
Internet Protocol Security (IPSec) is a standards-based VPN that offers flexible solutions for
secure data communications across a public network like the Internet. IPSec is built around a
number of standardized cryptographic techniques to provide confidentiality, data integrity and
authentication at the IP layer. The following figure is an example of an IPSec VPN tunnel.
Figure 249 IPSec VPN Example
The VPN tunnel connects the ZyWALL (X) and the remote IPSec router (Y). These routers
then connect the local network (A) and remote network (B).
20.1.1 What You Can Do in the IPSec VPN Screens
• Use the VPN Connection screens (see Section 20.2 on page 353) to specify which VPN
gateway a VPN connection policy uses and which devices (behind the IPSec routers) can
use the VPN tunnel and the IPSec SA settings (phase 2 settings). You can also activate /
deactivate and connect / disconnect each VPN connection (each IPSec SA).
• Use the VPN Gateway screens (see Section 20.2.1 on page 355) to manage the
ZyWALL’s VPN gateways. A VPN gateway specifies the IPSec routers at either end of a
VPN tunnel and the IKE SA settings (phase 1 settings). You can also activate and
deactivate each VPN gateway.