Users Manual Part 2

Device Configuration
Advanced Setup – NAT
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BEC 4700A / 4700AZ User Manual
NAT
The NAT (Network Address Translation) feature transforms a private IP into a public IP, allowing
multiple users to access the internet through a single IP account, sharing the single IP address. NAT
break the originally envisioned model of IP end-to-end connectivity across the internet so NAT can
cause problems where IPSec/ PPTP encryption is applied or some application layer protocols such as
SIP phones are located behind a NAT. And NAT makes it difficult for systems behind a NAT to accept
incoming communications.
NAT Status: Enabled. (Disabled if WAN connection is in BRIDGE mode)
VPN Passthrough: VPN pass-through is a feature of routers which allows VPN client on a private
network to establish outbound VPNs unhindered.
SIP ALG: Enable the SIP ALG when SIP phone needs ALG to pass through the NAT. Disable the SIP
ALG when SIP phone includes NAT-Traversal algorithm.
Interface: Select a WAN interface connection to allow external access to your internal network.
Click DMZ or Virtual Server to move on to set the DMZ or Virtual Server
parameters, which are represented in the following scenario.