How do we determine IP Address of interface the packet arrived on

[Vlad Dogaru]

On Wed, Sep 24, 2014 at 10:19:34AM +0530, Maninder Singh wrote:
> Hi,
> 
> Each time a packet arrives at a router in a subnet during transit, I
> need to determine the IP address of the incoming interface of the
> router for that packet. I have a netfilter kernel module running at
> each router but I dont understand which data structure will give me
> thw IP address. Can someone please suggest how shall I get that?

An interface can have more than one IP address, so your question is a
little strange.

However, you can find out all the IPv4 addresses a particular device has
by iterating through dev->ip_ptr->ifa_list.

Hope this helps,
Vlad