El miércoles, 19 de octubre de 2016, 17:23:40 (UTC+2), emacsu...@gmail.com
escribió:
> El miércoles, 19 de octubre de 2016, 12:46:45 (UTC+2), Vadim Kochan
> escribió:On Wed, Oct 19, 2016 at 1:38 PM, <emacsu...@gmail.com> wrote:
>
> > Hello.
>
> >
>
> > I'm having a problem when trying to send packets with trafgen to the
> > loopback interface.
>
> >
>
> > Packets sent this way do not reach their destination.
>
> >
>
> > However, if packets are sent from an external machine, then I have no
> > problem at all to receive these packets at the destination application.
>
> >
>
> > I use "-o lo" option on the command line when executing trafgen.
>
> >
>
> > I suspect the problem is that I'm building an incorrect packet, and the
> > kernel is discarding it.
>
> >
>
> > The ethernet header on my cfg file looks like the following:
>
> >
>
> > --------------------------------------
>
> > #include <stddef.h>
>
> >
>
> > {
>
> > fill(0x00, ETH_ALEN),
>
> > fill(0x00, ETH_ALEN),
>
> > c16(ETH_P_LOOP),
>
> > c32(0x00),
>
> >
>
> > ......
>
> >
>
> > (Both source and destination IP addresses are set to 127.0.0.1)
>
> > --------------------------------------
>
> >
>
> > I have tried other combinations, like removing the ethernet header
> > completely, for instance.
>
> >
>
> > None of them worked.
>
> >
>
> > How does the ethernet header have to to look like, when you want trafgen to
> > generate a valid packet to be sent thru the loopback interface?
>
> >
>
> > Thanks a lot.
>
> > -Bob
>
> >
>
> > --
>
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>
>
>
> Hi Bob,
>
>
>
> Does it work if to increase packet length to 64 bytes length ?
>
>
>
> Sorry, I have no time to check it right now, will do it later if the
>
> above's approach did not help.
>
>
>
> Regards,
>
> Vadim Kochan
>
>
>
>
>
>
> Hi Vadim.
>
>
> Thanks for the prompt response.
>
>
> So far, I have been using the ETH_P_LOOP value (96), to indicate that the
> packet corresponds to a loopback packet.
> Given that that field is used for both type and length, if I'm understanding
> you correctly, you want me to change it to a value indicating the length of
> my entire packet, and not the value of ETH_P_LOOP.
> I suppose you said 64 as an example, and the value there should in fact
> correspond to my actual packet length.
>
>
> I have followed this approach, but the packet does not reach my application,
> still.
>
>
> In fact, on second thoughts, I cannot see the point on using ETH_P_LOOP value
> at all in the ethernet header, since its value is 96, which means that we
> have to interpret that value as a length, but the packet length can be
> anything.
>
>
> Not sure if I'm missing something here ....
>
>
> Any idea?
>
>
> Thanks.
> -Bob
>
>
>
>
>
>
>
Hello.
Any idea on why I'm not able to make traffic get to its destination thru the
loopback interface?
Not sure if the problem is the ethernet header I'm using. I guess so, but I
have tried all combinations with no success.
Thanks.
-Bob
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