User manual

4300T User Manual Edgewater Networks, Inc.
Version 1.7 31
Data Networking Configuration
The 4300T provides static IP routing and two types of Network Address Translation
(NAT) functions for data traffic. This chapter explains the use and configuration of
these features.
NAT for Data Traffic
NAT allows hosts on a private internal network
(the LAN side of the 4300T) to anonymously
communicate with devices on an external
network (the WAN side of the 4300T). The
4300T with NAT enabled will re-write
outbound packet headers using public IP
addresses in place of private IP addresses so
that the private IP addresses are not exposed
to the external network. Additionally, the
ports used by the IP addresses are also
changed as they traverse the 4300T. This is
known as Port Address Translation (PAT) and
provides an additional security measure. The
4300T maintains a table of these mappings so
that return packets can be forwarded to the
correct host on the private network.
The 4300T provides two types of NAT
functions: dynamic NAT and static NAT.
Dynamic NAT allows many private IP addresses to be mapped to a single public IP
address (using different port numbers of the public IP address). Static NAT maps
private IP addresses and port. For example, mapping a public IP address to a
specific machine on the private network responsible for receiving email.
PLEASE note: The 4300T ALG automatically handles NAT for voice devices as
described in Chapter 3 “VoIP Configuration”.
Configure Dynamic NAT
Use Dynamic NAT when you have multiple PCs installed on the LAN side of the 4300T
that require Internet or WAN access. Once Dynamic NAT is enabled the 4300T will
automatically perform an address translation for all packets to/from the LAN side
PCs.
A. From the Configuration Menu select NAT.
B. Use the Enable Lan NAT checkbox to enable or disable dynamic NAT.
The default value for dynamic NAT is enabled.
C. Press Submit.
Configure Static NAT
Use Static NAT when a server or PC located in the private network needs to be
accessible from the external network. Some examples include a corporate web