Re: [Bugme-new] [Bug 12109] New: Multicast packets with TTL 0 sent out if not local listener

Re: [Bugme-new] [Bug 12109] New: Multicast packets with TTL 0 sent out if not local listener

[Andrew Morton]

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Thu, 27 Nov 2008 02:32:27 -0800 (PST) bugme-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=12109
> 
>            Summary: Multicast packets with TTL 0 sent out if not local
>                     listener
>            Product: Networking
>            Version: 2.5
>      KernelVersion: 2.6.27
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: IPV4
>         AssignedTo: shemminger@linux-foundation.org
>         ReportedBy: jani@ubuntu.com
> 
> 
> According to what I have read, setting the IP_MULTICAST_TTL option to 0 on a
> multicast sending socket should prevent it sending to the network, and be
> destined only for listeners on the local computer.
> 
> This only seems to work if there is a local listener on that particular group.
> If such a listener app is stopped other computers on the LAN get the messages,
> and tcpdump -v shows they have  TTL 0
> 
> I am not sure if this is intended behaviour but it is unexpected.
> 
>