[Xorp-hackers] A problem with the Router Alert option

Nenad Vukmirovic nenad.vukmirovic at etf.rs
Tue Sep 11 10:29:31 PDT 2012


I have a question about raw IPv4 packet input/output.

I am working on a new XORP module (protocol) which uses raw IPv4 IO and
relies on the Router Alert option to work properly. I have managed to send
packets with that option (flag) set to ON successfully so far. I have also
received packets that have the destination IP address of my router (in the
IP header).

However, it seems I cannot receive packets (with the Router Alert flag
turned on) whose destination IP address doesn't match any address on my
router.

I have checked that those packets arrive at my router and that my router
forwards them to their final destination, but those packets don't get
inspected by my protocol (running on the router).

Does anyone know if FEA is capable of letting such packets into the
protocol to be inspected automatically? If it is, what part of my code
should I change to make it work?

Yours faithfully,
Nenad Vukmirovic




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