commit a5a5990c099dd354e05e89ee77cd2dbf6655d4a1 upstream. IPTables commands using 'iptables-nft' fail on old kernels, at least on v5.15 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: dc65fe82fb07 ("selftests: mptcp: add packet mark test case") Cc: stable@vger.kernel.org Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>