2.4 NAT Firewall
The X4’s built-in NAT (Network Address Translation) firewall provides a good, but not perfect, level of protection from unauthorized access. NAT keeps private a network’s internal IP addresses and presents to the Internet a set of public IP addresses. NAT’s more robust counterpart, NAPT (Network Address Port Translation), replaces a network’s private IP addresses with a single public IP address. Both NAPT and NAP are transparent to end users.
Your X4’s NAT firewall is enabled by default; the default setting is dynamic NAPT—everything is automatic. 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 NAPT. Options are Disable and NAT. You | |
| | should not need to change this setting, unless | |
| | advised to do so by your provider. Note: If you | |
| | select Disable, all your modem’s firewall capabilities | |
| | are turned off. | |
| Session Name | Only applicable to NAT; 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. | |
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| 22 | X4 ADSL Modem User’s Manual | |
