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Pablo Neira Ayuso authored
This patch adds a new flag that signals the kernel to update layer 4 checksum if the packet field belongs to the layer 4 pseudoheader. This implicitly provides stateless NAT 1:1 that is useful under very specific usecases. Since rules mangling layer 3 fields that are part of the pseudoheader may potentially convey any layer 4 packet, we have to deal with the layer 4 checksum adjustment using protocol specific code. This patch adds support for TCP, UDP and ICMPv6, since they include the pseudoheader in the layer 4 checksum calculation. ICMP doesn't, so we can skip it. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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