Reference Manual

HOW TO use NAT32 as a Traffic Manager for an external Router.


You have a DSL Router or a Cable Modem Router (or even just a PC running Windows ICS) to which your private machines send their Internet traffic. You would like to mangage traffic from your private machines to the Internet so that certain applications are blocked, or certain machines are blocked, or that certain Internet sites are not accessible.


The basic idea behind this solution is to reconfigure all your private machines (except the NAT32 machine) so that they use NAT32's private IP address as their default gateway rather than the external router. This can be done manually on each machine by executing the following commands in a Windows Console (DOS Box):

route delete mask
route add mask
The above example assumes your private LAN network address is and that NAT32 is at

From then on, your private machines will send all their Internet traffic to NAT32 rather than to the external router, and various NAT32 features can then be used to process that traffic before it is passed on to the external router for forwarding to the Internet. Your external router will still send all traffic from the Internet directly to your private machines, as it does not know that NAT32 exists.

Traffic Filters

The NAT32 filtering mechanisms are simple yet powerful.

The Administration feature lets you limit throughput for any machine or even block the machine's access to the Internet after a certain period of time has elapsed or a set amount of data has been uploaded.

The Filter feature can be used to delay or discard specific traffic from specific machines. For example, if you want to throttle all FTP transfers for all machines and for all FTP sites, the following filter could be applied:

setf 1 add 0 0 0 0 6 0 20 500
The above filter will delay the transmission of all outgoing TCP Port 20 segments by 500 msec, and this will effectively reduce the total bandwidth that the FTP transfer uses. Meanwhile, all the other machines (and all the other apps running on the machine doing the transfer) will have much better response times and users can continue working normally. Further details on how to configure this feature can be found here.

Additional Features

NAT32 has many additional features that allow you to interact with your external router, update Web Pages automatically or perform a large range of scripting tasks at specified times using cron.


admin, filter, rmode, route, Traffic Throttle
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