If you are looking for MPTCP in Linux >= v5.6:

https://mptcp.dev

For Linux <= 5.4, you can stay on this website.

Use MPTCP

If you have correctly installed the MPTCP-kernel and configured the routing tables as needed, you can start using MPTCP

Check

This server (multipath-tcp.org) is running the latest build of our kernel. Thus, every time you connect to this server you will be using MPTCP.

Download some files http://multipath-tcp.org/snapshots.

You can also visit http://amiusingmptcp.de to see how well your network supports MPTCP on different port-numbers.

No MPTCP at all

If it looks like you don't use MPTCP at all, please check these points:

  • Are you using a kernel with MPTCP?
    • sudo dmesg | grep MPTCP
  • Is MPTCP enabled?
    • sysctl net.mptcp.mptcp_enabled
  • Does the application create an MPTCP connection?
    • tcpdump -n -i <interface> tcp | grep mptcp
  • Is MPTCP blocked somewhere between the client and the server?
    • Visit http://amiusingmptcp.de and check the different ports
    • sudo tracebox -p 'IP/tcp{dst=443}/MPCAPABLE' multipath-tcp.org (See Tools)
    • Feel free to report such issues to the network owner (ISP, etc.): most of the time, it is a mistake or due to some default configurations.



MPTCP only with one path

If MPTCP is used but only with one path, please check:

  • Did you configure a path manager on the client side to establish more subflows?
  • Did you configure a path manager on the server side to announce more available IP addresses?
  • Did you configure the routing?
  • Is MPTCP blocked on some paths?
    • See above about tracebox.