gluon-ebtables-filter-multicast: block packets with Gluon VXLAN multicast destination #3477
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…cast destination An incorrectly connected node may send wired-mesh packets to another node's client port. For raw batman-adv, such frames are filtered by batman-adv, but this does not work with VXLAN encapsulation. While such packets are not flooded through the mesh because of the batman-adv noflood flag, they may still reach another node that is connected in the same incorrect way, which could result in loops and other connectivity issues. Filter out packets sent to our VXLAN multicast group address to avoid such problems. Fixes freifunk-gluon#3025
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rotanid
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An incorrectly connected node may send wired-mesh packets to another
node's client port. For raw batman-adv, such frames are filtered by
batman-adv, but this does not work with VXLAN encapsulation.
While such packets are not flooded through the mesh because of the
batman-adv noflood flag, they may still reach another node that is
connected in the same incorrect way, which could result in loops and
other connectivity issues.
Filter out packets sent to our VXLAN multicast group address to avoid
such problems.
Fixes #3025
Completely untested, but seems straightforward enough.
Another point for discussion: Do we want to remove some protocols from the gluon-ebtables-filter-multicast allowlist? Running Babel, OSPF or RIP-NG over a regular mesh seems like a bad idea, and unusual enough that requiring to disable the filter may be justified.