Edgewater Networks 4200 Series - Data Networking Configuration; NAT for Data Traffic

4200 User Manual Edgewater Networks, Inc.
Version 3.0 77
Data Networking Configuration
The 4200 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 4200) to
anonymously communicate with devices on an external network (the WAN side of the
4200). The 4200 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 4200. This is known as Port
Address Translation(PAT) and provides an additional security measure. The 4200
maintains a table of these mappings so that return packets can be forwarded to the
correct host on the private network.
The 4200 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 numbers to public IP addresses and port numbers on a
one-to-one basis.
PLEASE note: The 4200 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 4200
that require Internet or WAN access. Once Dynamic NAT is enabled the 4200 will
automatically perform an address translation for all packets to/from the LAN side
PCs.
A. Select NAT.
The default value for dynamic NAT is enabled.
B. Use the Enable Lan NAT checkbox to enable or disable dynamic NAT.
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
server, a mail server or an FTP server. In these instances, the 4200 statically maps
the public IP address of each server to the actual private IP address of the server.
PLEASE note: In order for Static NAT to function dynamic NAT must be enabled.
A. Select NAT.
B. Enter the public and private IP addresses and ports to be mapped in
Static NAT Client Entries using the following format:
Protocol;PublicIPAddress/netmask-port>PrivateIPAddress-port