IPTables commands using 'iptables-nft' fail on old kernels, at least
5.15 because it doesn't see the default IPTables chains:
$ iptables -L
iptables/1.8.2 Failed to initialize nft: Protocol not supported
As a first step before switching to NFTables, we can use iptables-legacy
if available.
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/368
Fixes: 8d014eaa92 ("selftests: mptcp: add ADD_ADDR timeout test case")
Cc: stable@vger.kernel.org
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
0c4cd3f86a