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Date:   Tue, 6 Jul 2021 15:28:03 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Callum Sinclair <callum.sinclair@alliedtelesis.co.nz>
Cc:     dsahern@kernel.org, nikolay@nvidia.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linus.luessing@c0d3.blue
Subject: Re: [PATCH] net: Allow any address multicast join for IP sockets
Message-ID: <YORaY83GiD56/su0@lunn.ch>
References: <20210706011548.2201-1-callum.sinclair@alliedtelesis.co.nz>
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On Tue, Jul 06, 2021 at 01:15:47PM +1200, Callum Sinclair wrote:
> For an application to receive all multicast packets in a range such as
> 224.0.0.1 - 239.255.255.255 each multicast IP address has to be joined
> explicitly one at a time.
> 
> Allow the any address to be passed to the IP_ADD_MEMBERSHIP and
> IPV6_ADD_MEMBERSHIP socket option per interface. By joining the any
> address the socket will receive all multicast packets that are received
> on the interface. 
> 
> This allows any IP socket to be used for IGMP or MLD snooping.

Do you really want all multicast frames, or just IGMP and MLD
messages?

What is the advantage of this solution over using pcap with a filter
which matches on multicast?

      Andrew