User's Manual

ISG50 User’s Guide 367
CHAPTER 24
IPSec VPN
24.1 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 246 IPSec VPN Example
The VPN tunnel connects the ISG50 and the remote (peer) IPSec router (X). These routers then
connect the local network (A) and remote network (B).
Note: You can use a subscription to increase the number of supported IPSec VPN tunnels.
See Chapter 11 on page 229.
24.1.1 What You Can Do in this Chapter
•Use the VPN Connection screens (see Section 24.2 on page 370) 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 24.2.1 on page 371) to manage the ISG50’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.
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