Zyxel ZyWALL USG 50 [28/185] Configuration steps

ZyWALL USG Support Notes

Please not that for the web server forwarding firewall rule, the service is http TCP port

80 instead of TCP 8080. Because in general packet flow, DNAT process precedes

firewall checking.

1.4. Setting up One to One NAT

1.4.1. Network Scenario

One to One NAT makes sure one local IP maps to one unique global IP, no matter the

traffic is outgoing from local to internet, or incoming from internet to local.

In the scenario above, we map the WAN global IP 200.0.0.1 to the intranet web server

192.168. 1.5. So, when an http client on the internet wants to access the server, its

original IP is 200.0.0.1. After the USG receives the traffic, it maps the destination

address to 192.168.1.5. When the server replies, its original source IP is 192.168.1.5,

when USG receives it, it will translate the source to 200.0.0.1 and send out to the

internet client.

After the One to One NAT rule is set, the USG will automatically generate a One to

One routing rule in the system, as discussed in section 1.1.2 Routing priority. So

when the server 192.168.1.5 initiates traffic to access internet, if there‟s no applicable

policy route, the USG will use this One to One routing, send out the traffic through

the WAN interface 200.0.0.1, and maps the source address to 200.0.0.1.

1.4.2. Configuration Steps

Step1. Go to Configuration > Network > NAT, click Add button to add one NAT rule.