Zoom X5 2.4 NAT Firewall, NAT, NAPT, dynamic, Advanced Setup

2.4 NAT Firewall

The X5’s built-in NAT (Network Address Translation) firewall provides a good level of protection from unauthorized access. NAT keeps private a network’s internal IP addresses and presents to the Internet one public IP address. With NAT, only one LAN user can use the public IP address. NAT’s more robust counterpart, NAPT (Network Address Port Translation), allows specified LAN users to share the one public IP address. Both NAPT and NAT are transparent to end users.

Your X5’s NAT firewall is enabled by default; the default setting is dynamic NAPT—everything is automatic. With dynamic NAPT, anyone can use the public IP address (that is, the modem’s WAN IP address). You shouldn’t need to change this setting. However, if your service provider instructs you to disable it (or change it), go to the Advanced Setup page and click the NAT button.

NAT	Default is dynamic NAPT. Options are NAPT, NAT,
	and Disable. You should not need to change this
	setting, unless advised to do so by your provider.
	Warning: If you select Disable, all your modem’s
	firewall capabilities are turned off.
Session Name	Only applicable to NAT and NAPT; user-definable
	name to differentiate between different NAT
	sessions, different PPP sessions, and different
	PVCs.
User’s IP	IP address of the client computer you want to add.
Action	Choices are Add or Delete.
Chapter 2: Advanced Setup Options		21