Drop IP unicast packets encapsulated in link-layer multi- or broadcast frames
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area: networking
priority: p2
type: enhancement
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Description
[RFC 1122 3.3.6](https://tools.ietf.org/html/rfc1122#page-67) states:
When a host sends a datagram to a link-layer broadcast
address, the IP destination address MUST be a legal IP
broadcast or IP multicast address.
A host SHOULD silently discard a datagram that is received via
a link-layer broadcast but does not specify
an IP multicast or broadcast destination address.
Linux has this behavior turned off by default, and a user could turn it on using /proc/sys/net/ipv4/drop_unicast_in_l2_multicast. Link [sysctl variables](https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt)
gVisor doesn't handle the case.
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