Query on operstatus for link, can I change it?

[Jeff Haran]

> -----Original Message-----
> From: kernelnewbies-bounces at kernelnewbies.org [mailto:kernelnewbies-
> bounces at kernelnewbies.org] On Behalf Of Amit Agarwal
> Sent: Tuesday, July 14, 2015 5:14 AM
> To: Kernelnewbies
> Subject: Query on operstatus for link, can I change it?
> 
> 
> Hi,
> 
> I am looking for a way to change the operstatus shown for the network
> interface.
> 
> Problem:
> I have an extra interface on the machine that I would like to use for some
> program like tcpreplay and tcpdump/wireshark. So, I would like to play a pcap
> file on this interface and then capture on the same interface with wireshark.
> Now the problem with this is that unless a cable is plugged in I do not see any
> packets in wireshark, although I do not see any failures in sending the
> packets. I would like to do this without any cable being plugged in as I do not
> intend to send the packets out, is this possible?
> 
> The reason I cannot use lo interface for doing this is: there will be other
> packets on the lo interface and I want to capture only the packets in the pcap
> file that I am playing with tcpreplay.
> 
> Thanks in advance for any advice on this.
> 
> --
>  Thanks,
> -aka

You might be able to make something like this work using network namespaces and veth devices. Depends on whether you really need to use your extra physical interface as the tcpreplay device.

Jeff Haran