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gluon-ebtables: don't filter incoming MLD Reports via ebtables
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If there is no multicast router behind a bridge port then the Linux
bridge multicast snooping code itself will refrain from forwarding a
report, as recommended/required by RFC4541
("Considerations for Internet Group Management Protocol (IGMP)
  and Multicast Listener Discovery (MLD) Snooping Switches).
So these rules are in most cases redundant.

On the other hand, removing them allows to actually run an IPv6
multicast router behind a Gluon node. Since OpenWrt 23.05 it will allow
detecting multicast routers via Multicast Router Discovery (RFC4286).
And removing these ebtables rules will allow a layer 3 multicast router
to then receive MLD reports from the mesh properly and by that to learn
about others listeners in the mesh.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
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T-X committed Mar 26, 2024
1 parent 3f236c1 commit 0858812
Showing 1 changed file with 0 additions and 4 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,4 @@ if site.mesh.filter_membership_reports(true) then
rule('MULTICAST_OUT_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 131 -j DROP') -- MLDv1 Report
rule('MULTICAST_OUT_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 132 -j DROP') -- MLDv1 Done
rule('MULTICAST_OUT_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 143 -j DROP') -- MLDv2 Report

rule('MULTICAST_IN_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 131 -j DROP', 'nat') -- MLDv1 Report
rule('MULTICAST_IN_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 132 -j DROP', 'nat') -- MLDv1 Done
rule('MULTICAST_IN_ICMPV6 -p IPv6 --ip6-protocol ipv6-icmp --ip6-icmp-type 143 -j DROP', 'nat') -- MLDv2 Report
end

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