[libvirt] [tck PATCH v2 3/5] filter for proper IP address in tcpdump looking for broadcast packet

[Stefan Berger]

On 02/08/2018 02:19 PM, Laine Stump wrote:
> In the no-mac-broadcast test, a ping is sent to 192.168.122.255, but
> tcpdump is set to look for packets with a destination IP of
> 255.255.255.255. Change it to check for the correct IP address and
> also for mac broadcast (which is what the no-mac-broadcast filter
> actually looks at). This should eliminate the "false success" that was
> happening because tcpdump wasn't actually seeing the broadcast packet
> the guest was sending, as well as catching the "false failure" caused
> by tcpdump seeing other traffic from the guest unrelated to the test
> (which happened to be broadcasts sent to 255.255.255.255).
>
> Signed-off-by: Laine Stump <laine at laine.org>
Review-by: Stefan Berger <stefanb at linux.vnet.ibm.com>

> ---
>
> Unchanged from V1, it just had no review.
>
>   scripts/nwfilter/230-no-mac-broadcast.t | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/nwfilter/230-no-mac-broadcast.t b/scripts/nwfilter/230-no-mac-broadcast.t
> index 6ab20d8..758005c 100644
> --- a/scripts/nwfilter/230-no-mac-broadcast.t
> +++ b/scripts/nwfilter/230-no-mac-broadcast.t
> @@ -80,7 +80,7 @@ ok($ebtable =~ "-d Broadcast -j DROP", "check ebtables entry for \"-d Broadcast
>
>   # prepare tcpdump
>   diag "prepare tcpdump";
> -system("/usr/sbin/tcpdump -v -i virbr0 -n host 255.255.255.255 2> /tmp/tcpdump.log &");
> +system("/usr/sbin/tcpdump -v -i virbr0 -n host 192.168.122.255 and ether host ff:ff:ff:ff:ff:ff 2> /tmp/tcpdump.log &");
>
>   # log into guest
>   diag "ssh'ing into $guestip";