Create a one-to-many tunnel

[Vimal]

Hi,

I wish to create an IP in IP tunnel interface that works as follows:

At the sender:
* The interface checks the dst IP address on the IP packet that it receives.
* It encapsulates the IP packet inside another IP packet with:
   Field 1: source address = the interface's IP address
   Field 2: dst address = the packet's dst IP address
* The interface now transmits the packet

This is different from normal IPinIP tunnels because it is not
point-to-point.  The operation in Field 2 is similar to NAT.  Also,
this is different from SNAT, because I want the receiver to know what
the original source IP.

At the receiver, assume that there is a stack that understands this
special IPinIP packet and has a way to handle it.

If it's too specific, then I do not mind implementing it.

Thanks,
-- 
Vimal