[Click] Very strange ToHost functionality

[Bart Braem]

Hello,

When trying to figure out how to let ToHost work in userlevel to get a simple 
ping cross the network I tried to use EnsureEther to ensure the ethernet 
addresses of what goes to ToHost correspond to the ones with the Arpresponder 
on FromHost. That didn't work out but I changed the Arpresponder to always 
overwrite the existing headers and it worked. 
Now I began wondering why and how this is possible and I changed the 
destination addresses of the arpresponder to non-existant addresses in my 
network and pinging still works. Of course I tried removing ensureether but 
then pinging doesn't work any more... 
So my question comes down to: how do you properly set up the arpresponders to 
work for fromhost and tohost? My configuration is based on one tun device and 
one real device. The real device is put in promiscuous mode and all traffic 
is said to originate from the tun devices. I then try to ping from one tun 
device to the other one.
I'll try to distill a small configuration, currently there are AODV elements 
in the way...

Bart