User`s guide

IP address

Enable standard Network Address Translation (NAT).

When a private IP host sends a UDP or TCP packet to an Internet IP address, the router

will change the source address of the packet from the private host IP to the router’s

public IP address before forwarding the packet onto the Internet host. Additionally it will

create an entry in a “NAT table” containing the private IP source address, the private IP

port number, the public IP destination address and the destination port number.

Conversely, when the router receives a reply packet back from the public host, it checks

the source IP, source port number and destination port number in the NAT table to

determine which private host to forward the packet to. Before it forwards the packet back

to the private host, it changes the destination IP address of the packet from its public IP

address to the IP address of the private host.

IP address and Port

Enable Network Address and Port Translation (NAPT).

This mode behaves like NAT but in addition to changing the source IP of the packet from

the private host it can also change the source port number. This is required if more than

one private host attempts to connect using the same local port number to the same

Internet host on the same remote port number. If such a scenario were to occur with

NAT the router would be unable to determine which private host to route the returning

packets to and the connection would fail.

NAT Source IP address

If specified, and NAT mode has been set to “NAT” or “NATP” for this interface, then the

source address of packets being sent out this interface is changed to this address, rather

than the interface address.

Enable IPsec on this interface

The IPSec parameter is used to enable or disable IPSec processing on this interface. If

this box is ticked, packets sent or received on this interface must pass through the IPSec

code before being transmitted. IPSec may drop the packet, pass it unchanged, or encrypt

and encapsulate within an

IPSec packet.

Keep Security Associations (SAs) when this Mobile interface is disconnected

This checkbox will configure the router to keep any existing IKE and IPsec associations

should the link drop. This is usually applied on head-end routers with fixed IP addresses.

Use interface X, Y for the source IP address of IPsec packets

By default, the source IP address for an IPSec Eroute will be the IP address of the

interface on which IPSec was enabled. By setting this parameter to either a PPP or

Ethernet interface, the source IP address used by IPSec will match that of the Ethernet or

PPP interface specified.

Enable the firewall on this interface

The Firewall parameter is used to turn Firewall script processing “On” or “Off” for this

interface.

Note:

If the firewall is enabled on an interface and with the absence of any firewall rules, the

default action is to block ALL traffic.

To configure the firewall see Configuration – Security > Firewall

Limit the data transmitted over this interface