如何确认系统是否使用MPTCP？检测异常问题咨询

Hey there! From what you've described, it's very likely your system is actively using MPTCP—here's a breakdown of why, plus ways to confirm further:

Why Wireshark's Output Matters More Than the Website Check #

Wireshark captures raw network packets directly from your eth1 interface, so seeing MPTCP-related entries there is concrete, first-hand evidence. Those entries typically include:

• MPTCP control packets like MP_CAPABLE (used to negotiate MPTCP during connection setup)
• Data packets with MPTCP header options (indicating ongoing MPTCP data transfer)

The website-based check failing could stem from a few common, non-conclusive issues:

• The tool might only test connections over standard ports (like 80/443) while your MPTCP usage is limited to other apps/ports
• The check might route traffic through a different interface (not eth1) where MPTCP isn't enabled
• Some detection tools have limited logic and don't recognize all MPTCP implementation variants

Quick Command-Line Checks to Confirm #

To be 100% sure, run these commands on your system:

• Verify if MPTCP is enabled at the kernel level:

  sysctl net.mptcp.enabled
  

  A return value of 1 means MPTCP is turned on.
• List active MPTCP connections:

  ss -tulmp | grep mptcp
  

  Any output here shows live MPTCP connections in use.
• Check MPTCP endpoint configurations (for eth1 specifically):

  ip mptcp endpoint show
  

  This will list interfaces configured for MPTCP, including eth1 if it's set up.

If your Wireshark capture shows valid MPTCP packet exchanges, that's the most reliable indicator—don't worry about the website check failing.

内容的提问来源于stack exchange，提问作者umer