selftests: mptcp: sockopt: use 'iptables-legacy' if available

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: [email protected]
Acked-by: Paolo Abeni <[email protected]>
Signed-off-by: Matthieu Baerts <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
1 file changed