Question about fragmenting and NF_IP_FORWARD

[Alexey Vyskubov]

Hello.

I have few questions.

I need to write NF hook which will completely change skb in
NF_IP_FORWARD hook. E.g. it may change output device for the packet or
unset DF bit.

But if the packet is too big for the original device and DF bit was set
in original skb, it will be dropped before NF_IP_FORWARD. Actually it's
not good because I need to take special actions for these kind of
packets.
Is there some way to receive the packet in some hook before it will be
dropped?

The second question. It seems to me that the packet can be dropped
before NF_LOCAL_OUT hook -- if there is no route for the packet.
Let's suppose that I'd like to write NF hook which will use IP-over-IP
for handling some of packets... Again, no way to receive the packet in
hook?

The third question. It seems to me that some packets could be fragmented
before NF hook. Hook may change routing (hence MTU for output device
may be different with MTU used during fragmentation). Is it good?

-- 
Alexey