ZyXEL Communications ZyWALL5UTM 4.0 User Manual
ZyWALL 5/35/70 Series User’s Guide
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Chapter 18 Introduction to IPSec
Figure 143 Encryption and Decryption
18.1.3.2 Data Confidentiality
The IPSec sender can encrypt packets before transmitting them across a network.
18.1.3.3 Data Integrity
The IPSec receiver can validate packets sent by the IPSec sender to ensure that the data has not
been altered during transmission.
been altered during transmission.
18.1.3.4 Data Origin Authentication
The IPSec receiver can verify the source of IPSec packets. This service depends on the data
integrity service.
integrity service.
18.1.4 VPN Applications
The ZyWALL supports the following VPN applications.
18.1.4.1 Linking Two or More Private Networks Together
Connect branch offices and business partners over the Internet with significant cost savings
and improved performance when compared to leased lines between sites.
and improved performance when compared to leased lines between sites.
18.1.4.2 Accessing Network Resources When NAT Is Enabled
When NAT is enabled, remote users are not able to access hosts on the LAN unless the host is
designated a public LAN server for that specific protocol. Since the VPN tunnel terminates
inside the LAN, remote users will be able to access all computers that use private IP addresses
on the LAN.
designated a public LAN server for that specific protocol. Since the VPN tunnel terminates
inside the LAN, remote users will be able to access all computers that use private IP addresses
on the LAN.
18.1.4.3 Unsupported IP Applications
A VPN tunnel may be created to add support for unsupported emerging IP applications. See
for an example of a VPN application.