Table of Contents
Advertisement
M2M Cellular Gateway
3.9 NAT / Bridge
Network address translation (NAT) is a methodology of remapping one IP address space into
another by modifying network address information in Internet Protocol (IP) datagram packet headers
while they are in transit across a traffic routing device. The technique was originally used for ease of
rerouting traffic in IP networks without renumbering every host. It has become a popular and essential
tool in conserving global address space allocations in face of IPv4 address exhaustion. AMIT products
embed and activate the NAT function by default except the Access Point series of products. You also
can disable it in [Basic Network]‐[WAN]‐[Internet Setup]‐[WAN Type Configuration].
Following features are included in the NAT function: NAT Loopback, Virtual Server, Virtual
Computer, Special AP, ALG and DMZ Host.
3.9.1 NAT Configuration
For gateway products, NAT function is activated by default. For device supporting multiple WAN
interfaces, enabling and disabling NAT function can be done on each WAN. You can configure it in
[Basic Network]‐[WAN]‐[Internet Setup]‐[WAN Type Configuration] page.
Normally, with global IP address or FQDN of WAN interface in the gateway, employees who travel
outside the office can access various servers behind the office gateway. You can set up those servers
by using "Virtual Server" feature of the gateway (refer to next section) to forward all server accessing
requests to local LAN servers for traveling employees for remote access. But most often, employees
are to reconfigure their PC to access to those servers from inside the LAN network each time after their
trip. NAT Loopback can be enabled to overcome. In web‐based utility, refer to "Configuration" page, for
"NAT Loopback" feature which can be found in [Basic Network]‐[NAT/Bridging]‐[Configuration].
"Virtual Server" feature can be found in [Basic Network]‐[NAT/Bridging]‐[Virtual Server & Virtual
Computer].
With "Virtual Server" feature, traveling employees may thus access office servers using the FQDN
or IP address of WAN interface in the gateway, and the accessing request packets will be delivered to
the WAN interface of gateway after NAT translation. Gateway forwards the inbound request packets to
the local LAN servers and LAN servers make a reply to these request packets by connection tracking
back. But if the NAT Loopback feature in the gateway is enabled, these packets will not flow to the
WAN interface, but only loopback to the local LAN servers. And LAN servers make a reply.
Index skipping is used to reserve slots for new function insertion, when required.
87
Advertisement
Table of Contents
