[FFmpeg-devel] [PATCH] Avoid sending packets to network when multicast ttl is 0 in udp

Omid Ghaffarinia omid.ghaffarinia at gmail.com
Tue Jul 19 16:48:28 EEST 2016

Is the patch approved or does it need more explanation?

On Wed, Jul 13, 2016 at 3:09 PM, Omid Ghaffarinia
<omid.ghaffarinia at gmail.com> wrote:
> I attached the patch.
> The actual bug is, when creating a local multicast stream (i.e. giving
> "rtp://" to avio_open), then you can see the
> packets on the network and not just on local machine (despite setting
> multicast ttl to 0) which was a security bug in my purpose of usage
> (it also made a lot of unused traffic on network)
> The user does not choose to enable/disable the kernel hack, that is
> how it is designed.
> This behavior does NOT happen in Windows machines, but the patch given
> does no harm at all (it does nothing in Windows)
> On Wed, Jul 13, 2016 at 3:12 AM, Moritz Barsnick <barsnick at gmx.net> wrote:
>> On Tue, Jul 12, 2016 at 18:31:36 +0430, Omid Ghaffarinia wrote:
>> Your mailer has broken the patch by inserting line breaks. You should
>> try attaching the patch as a file, or directly using "git send-email".
>>> Bug is due to kernel handling multicast ttl 0 differently (as noted in
>>> kernel code net/ipv4/route.c:2191 see:
>> ffmpeg is not a Linux-only tool/library, so comments should point out
>> which "kernel" more precisely (and possibly which versions this applies
>> to). Admitted, the link to github contains the string "linux". ;-)
>> Furthermore: Please explain what the actual bug (i.e. misbehavior) is,
>> and what this fix changes (or how it fixes it).
>> Are you allowing ffmpeg to work when the user is making use of the
>> kernel hack?
>> What does this patch achieve on non-Linux operating systems?
>> (Sorry for the stupid questions, all this isn't obvious to me, and I do
>> have at least some understanding of network stuff.)
>> Moritz
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