How can i use the mptcp socket api?

Question

I followed this to use the MPTCP Socket API. my mptcp setting (mptcp_enabled=2

I wrote the echo server(localhost) and client in c. And I used tcpdump to capture between(server - client).

But I failed, because packet not with the mptcp option. this is tcpdump result. (test message is "hello")

This is server source code

And this client source code

What did I miss?

Answer 1

I got the solution..
My problem is that the server used the localhost address.