ZyXEL Communications 2 Plus User Manual

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ZyWALL 2 Plus User’s Guide
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 14 
IPSec VPN
This chapter explains how to set up and maintain IPSec VPNs in the ZyWALL. First, it 
provides an overview of IPSec VPNs. Then, it introduces each screen for IPSec VPN in the 
ZyWALL.
14.1  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 provides one perspective of a VPN tunnel.
Figure 168   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).