[Click] can someone please explain how click deals with IP headers?

[Roman Chertov]

If you know the exact MAC where things should go then you can use 
EtherEncap as suggested; however, if you don't, then you can use ARPQuerier.



Seth Hall wrote:
> I believe that unstrip should do what you want if you want the  
> original ethernet header put back.
>     http://read.cs.ucla.edu/click/elements/unstrip
> 
> You can build your own ethernet header with etherencap.
> 
>   .Seth
> 
> On Oct 25, 2007, at 2:12 PM, Daniel McBrearty wrote:
> 
>> Thanks Roman. I was starting to suspect this. I guess the same applies
>> to other modules that expect IP packets.
>>
>> Next question : when you are done processing the raw IP, how do you
>> put an ethernet header back on, prior to the Queue() -> ToDevice()
>> combination?
>>
>> cheers
>>
>> On 10/25/07, Roman Chertov <rchertov at purdue.edu> wrote:
>>> Daniel McBrearty wrote:
>>>> Hi
>>>>
>>>> Have been playing around with this great piece of software for a few
>>>> days. Had some success with it, but one thing seems to cause some
>>>> trouble.
>>>>
>>>> I seem not to be understanding something basic about how many  
>>>> elements
>>>> handle IP headers.
>>>>
>>>> For instance, if I have a config like this :
>>>>
>>>> ipc IPClassifier( ip proto udp, - );
>>>> FromDevice( etho, PROMISC true ) -> ipc;
>>>> ipc[0] -> Queue() -> ToDevice( eth1 );
>>>> ipc[1] -> Discard();
>>>>
>>>> Now, I run this in user mode, and send it a few hundred RTP packets.
>>>> It core dumps. The core dump goes if I remove ipc.
>>> It core dumps because it is trying to read IP headers from where
>>> Ethernet headers are.  You need to use a classifier first and then  
>>> strip
>>> 14 bytes before you can send packets to the IPClassifier.
>>>
>>> Roman
>>>
>>>> Other problems I have had have been trying to use SetIPAddress(
>>>> 1.2.3.4, dst ) in such a config, but the ip appears unchanged in
>>>> wireshark.
>>>>
>>>> Do these IP based elements expect the ethernet header to be stripped
>>>> off, or explicitly told the position relative to the start of an
>>>> ethernet header? I seem to remember seeing something like this  
>>>> when I
>>>> started reading the docs ... but I can't find that now.
>>>>
>>>> thanks
>>>>
>>>> Daniel
>>>> _______________________________________________
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>>>> click at amsterdam.lcs.mit.edu
>>>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>>>>
>>
>> -- 
>> Daniel McBrearty
>> email : danielmcbrearty at gmail.com
>> http://www.engoi.com
>> http://danmcb.vox.com
>> http://danmcb.blogger.com
>> find me on linkedin and facebook
>> BTW : 0873928131
>> _______________________________________________
>> click mailing list
>> click at amsterdam.lcs.mit.edu
>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
> 
> ---
> Seth Hall
> Network Security - Office of the CIO
> The Ohio State University
> Phone: 614-292-9721
> 
> 
> 
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