Add a script to exercise NAT port clash resolution with directional zones.
Add net namespaces that use the same IP address and connect them to a
gateway.
Gateway uses policy routing based on iif/mark and conntrack zones to
isolate the client namespaces. In server direction, same zone with NAT
to single address is used.
Then, connect to a server from each client netns, using identical
connection id, i.e. saddr:sport -> daddr:dport.
Expectation is for all connections to succeeed: NAT gatway is
supposed to do port reallocation for each of the (clashing) connections.
This is based on the description/use case provided in the commit message of
deedb59039 ("netfilter: nf_conntrack: add direction support for zones").
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>