[Click] Problems with KernelTun element

[jmorillo at ac.upc.edu]

Hello,

We were trying to use the KernelTun element in order to enable (userlevel) Click
to route traffic that is generated by the same computer. Firstly we created an
virtual interface through the KernelTun element and then we added a default
route towards this interface. The idea is that every packet generated by the
computer goes to this interface, and consequently to Click, and then they
follow the normal routing flow.

Well, as a first step we didn't introduce routing at all, we just wanted to make
sure that we were using KernelTun in the right way (and it seems that we are
not!). In this example, we want that every packet that arrives through tun0
goes directly to eth0. We copied below the only part of the configuration that
deals with KernelTun. In this machine we have three interfaces and we are
already able to do routing among them with this configuration file. The only
problem now is KernelTun.

elementclass FixChecksums {
    input -> SetIPChecksum
        -> ipc :: IPClassifier(tcp, udp, -)
        -> SetTCPChecksum
        -> output;
    ipc[1] -> SetUDPChecksum -> output;
    ipc[2] -> output
}

tun :: KernelTun(1.0.0.1/8)-> fromhost_cl :: Classifier(12/0806, 12/0800);
fromhost_cl[0] -> ARPResponder(0.0.0.0/0 1:1:1:1:1:1) -> tun;

_xorp_out0 :: Queue(200) -> _xorp_to_device0 :: ToDevice(eth0);
_xorp_arpq0 :: ARPQuerier(10.0.0.1, 00:0C:6E:F2:9B:6E) -> _xorp_out0;

fromhost_cl[1] -> Strip(14)
               -> StoreIPAddress(10.0.0.1, 12)         
               -> FixChecksums                         
               -> _xorp_arpq0

To test this configuration we did a ping to 10.0.0.4 which is directly connected
to the eth0 (10.0.0.1) interface of this computer. With etherreal we could see
that ICMP packet are being delivered to tun0, but they are not sent through
eth0. Anybody may help us? Thank you...

Cheers,

Julian