Chapter 12 NAT
NXC Series User’s Guide
193
12.3 Technical Reference
The following section contains additional technical information about the features described in this
chapter.
NAT Loopback
Suppose a NAT 1:1 rule maps a public IP address to the private IP address of a LAN SMTP e-mail server to
give WAN users access. NAT loopback allows other users to also use the rule’s original IP to access the
mail server.
Original Service This field is available if Port Mapping Type is Service. Select the original service whose
destination port(s) is supported by this NAT rule.
Mapped Service This field is available if Port Mapping Type is Service. Select the translated service whose
destination port(s) is supported if this NAT rule forwards the packet.
Protocol Type This field is available if Port Mapping Type is Port or Ports. Select the protocol (TCP, UDP, or Any)
used by the service requesting the connection.
Original Port This field is available if Port Mapping Type is Port. Enter the original destination port this NAT rule
supports.
Mapped Port This field is available if Port Mapping Type is Port. Enter the translated destination port if this NAT
rule forwards the packet.
Original Start Port This field is available if Port Mapping Type is Ports. Enter the beginning of the range of original
destination ports this NAT rule supports.
Original End Port This field is available if Port Mapping Type is Ports. Enter the end of the range of original
destination ports this NAT rule supports.
Mapped Start
Port
This field is available if Port Mapping Type is Ports. Enter the beginning of the range of translated
destination ports if this NAT rule forwards the packet.
Mapped End Port This field is available if Port Mapping Type is Ports. Enter the end of the range of translated
destination ports if this NAT rule forwards the packet. The original port range and the mapped
port range must be the same size.
Related Settings
Enable NAT
Loopback
Enable NAT loopback to allow users connected to any interface (instead of just the specified
Incoming Interface) to use the NAT rule’s specified Original IP address to access the Mapped IP
device. For users connected to the same interface as the Mapped IP device, the NXC uses that
interface’s IP address as the source address for the traffic it sends from the users to the Mapped
IP device.
For example, if you configure a NAT rule to forward traffic from the WAN to a LAN server,
enabling NAT loopback allows users connected to other interfaces to also access the server.
For LAN users, the NXC uses the LAN interface’s IP address as the source address for the traffic it
sends to the LAN server.
If you do not enable NAT loopback, this NAT rule only applies to packets received on the rule’s
specified incoming interface.
OK Click OK
to save your changes back to the NXC.
Cancel Click Cancel to return to the NAT summary screen without creating the NAT rule (if it is new) or
saving any changes (if it already exists).
Table 84 Configuration > Network > NAT > Add/Edit (continued)
LABEL DESCRIPTION
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