Default Server Ip Address; Port Forwarding: Services And Port Numbers; Pinging A Device Behind Nat From The Wan (Example) - ZyXEL Communications PMG5318-B20A User Manual

Chapter 7 NAT
Many residential broadband ISP accounts do not allow you to run any server processes (such as a
Web or FTP server) from your location. The ISP may periodically check for servers and may suspend
your account if it discovers any active services at your location. If you are unsure, refer to the ISP.
The basic rules of port forwarding are:
• If NAT is enabled, you must configure a port forwarding rule if you want traffic on the WAN to find
computers on the LAN.
• A port forwarding rule can only forward TCP and UDP traffic.
• If NAT is disabled, the GPON Device will route packets based on the information in the NAT
routing table.

7.2.1 Default Server IP Address

You can assign a default server IP address to which the GPON Device can forward traffic for all
protocols, such as TCP, UDP, ICMP (ping), ESP, and so on, that do not match an existing port
forwarding rule.
Note: If you do not assign a Default Server IP address, the GPON Device discards all
packets received for ports that are not specified in a port forwarding rule or in the
remote management setup.

7.2.2 Port Forwarding: Services and Port Numbers

Use the Port Forwarding screen to forward incoming service requests to the server(s) on your
local network.

7.2.3 Pinging a Device Behind NAT From the WAN (Example)

Imagine that you want to ping a device on the LAN behind your GPON Device from a remote
location on the WAN while NAT is enabled.
You cannot create a port forwarding rule for ping because ping uses the ICMP protocol; port
forwarding can only handle the TCP and UDP protocols.
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PMG5318-B20A User's Guide