ZyXEL Communications Internet Security Gateway ZyWALL 2 Series - Manual (Page 133)

ZyWALL 2 Series User’s Guide
NAT 8-11
Table 8-6 Address Mapping Rule
LABEL DESCRIPTION
Type Choose the port mapping type from one of the following.
1. One-to-One: One-to-one mode maps one local IP address to one global IP
address. Note that port numbers do not change for One-to-one NAT mapping type.
2. Many-to-One: Many-to-One mode maps multiple local IP addresses to one global
IP address. This is equivalent to SUA (i.e., PAT, port address translation), the Single
User Account feature.
3. Many-to-Many Ov (Overload): Many-to-Many Overload mode maps multiple local
IP addresses to shared global IP addresses.
4. Many One-to-One: Many One-to-one mode maps each local IP address to unique
global IP addresses.
5. Server: This type allows you to specify inside servers of different services behind
the NAT to be accessible to the outside world.
Local Start IP This is the starting Inside Local IP Address (ILA). Local IP addresses are N/A for
Server port mapping.
Local End IP This is the end Inside Local IP Address (ILA). If your rule is for all local IP addresses,
then enter 0.0.0.0 as the Local Start IP address and 255.255.255.255 as the Local
End IP address.
This field is N/A for One-to-One and Server mapping types.
Global Start IP This is the starting Inside Global IP Address (IGA). Enter 0.0.0.0 here if you have a
dynamic IP address from your ISP.
Global End IP This is the ending Inside Global IP Address (IGA). This field is N/A for One-to-One,
Many-to-One and Server mapping types.
Apply Click Apply to save your changes back to the ZyWALL.
Reset Click Reset to begin configuring this screen afresh.
8.6 Configuring Trigger Port
Some services use a dedicated range of ports on the client side and a dedicated range of ports on the server
side. With regular port forwarding you set a forwarding port in NAT to forward a service (coming in from
the server on the WAN) to the IP address of a computer on the client side (LAN). The problem is that port
forwarding only forwards a service to a single LAN IP address. In order to use the same service on a different
LAN computer, you have to manually replace the LAN computer's IP address in the forwarding port with
another LAN computer's IP address,
Trigger port forwarding solves this problem by allowing computers on the LAN to dynamically take turns
using the service. The ZyWALL records the IP address of a LAN computer that sends traffic to the WAN to
request a service with a specific port number and protocol (a "trigger" port). When the ZyWALL's WAN port