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

[maninder.tiet at gmail.com]

Hi.. Thanks for your reply. I agree that an interface can have more than one ipv6 addresses but in the PoC I am doing for an IP Traceback technique, I need to record a hash of the IP of incoming interface. For that I need to be able to read the packet.

Your reply gave me a direction to explore the use of dev->ip6_ptr->ac_list .. For ipv6.  However I m not sure what is ac_list and what is mc_list here.. I wonder if there is some documentation around it in this world. Can you please give me a pointer or if you could brief me about how do I list all ipv6 addresses of the interface.

Well, yet I tried to get the ip addresses pointed to by ac_list and before I could see if it displays something, system slows down unbelievably with syllogism error as 'takedown serio0. Some program might be trying to access hardware directly." And mouse stops moving. I am not sure if this error is a result of my operation or something else. I will try loading this module Again. But any comments from  your side on this please?



Thanks
Maninder


> On 24-Sep-2014, at 1:11 pm, Vlad Dogaru <ddvlad at herebedragons.ro> wrote:
> 
>> 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