ZyXEL Communications ADSL 2+ Security Gateway, User Manual

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Chapter 14 IPSec VPN
ZyWALL 2 Plus User’s Guide
290
14.15.2 Telecommuters Using Unique VPN Rules Example
In this example the telecommuters (A, B and C in the figure) use IPSec routers with domain
names that are mapped to their dynamic WAN IP addresses (use Dynamic DNS to do this).
With aggressive negotiation mode (see
Section 14.3.1.4 on page 260 ), the ZyWALL can use
the ID types and contents to distinguish between VPN rules. Telecommuters can each use a
separate VPN rule to simultaneously access a ZyWALL at headquarters. They can use
different IPSec parameters. The local IP addresses (or ranges of addresses) of the rules
configured on the ZyWALL at headquarters can overlap. The local IP addresses of the rules
configured on the telecommuters’ IPSec routers should not overlap.
See the following table and figure for an example where three telecommuters each use a
different VPN rule for a VPN connection with a ZyWALL located at headquarters. The
ZyWALL at headquarters (HQ in the figure) identifies each incoming SA by its ID type and
content and uses the appropriate VPN rule to establish the VPN connection.
The ZyWALL at headquarters can also initiate VPN connections to the telecommuters since it
can find the telecommuters by resolving their domain names.
Figure 191 Telecommuters Using Unique VPN Rules Example
Table 75 Telecommuters Sharing One VPN Rule Example
FIELDS TELECOMMUTERS HEADQUARTERS
My ZyWALL: 0.0.0.0 (dynamic IP address
assigned by the ISP)
Public static IP address
Remote Gateway
Address:
Public static IP address 0.0.0.0 With this IP address only
the telecommuter can initiate the
IPSec tunnel.
Local Network - Single
IP Address:
Telecommuter A: 192.168.2.12
Telecommuter B: 192.168.3.2
Telecommuter C: 192.168.4.15 192.168.1.10
Remote Network -
Single IP Address:
192.168.1.10 Not Applicable