otbr-agent not forwarding packet

[dakhnod]

Hello,

we encountered an Issue where the otbr-agent log shows the following entry:

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.983 [I] MeshForwarder-: Sent IPv6 TCP msg, len:80, chksum:1a49, ecn:no, to:cae403d199a67688, sec:yes, prio:low

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.983 [I] MeshForwarder-:     src:[fe80:0:0:0:ac1d:1c:86d:1da3]:58208

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.983 [I] MeshForwarder-:     dst:[fe80:0:0:0:c8e4:3d1:99a6:7688]:22

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.990 [I] MeshForwarder-: Received IPv6 TCP msg, len:60, chksum:38bf, ecn:no, from:cae403d199a67688, sec:yes, prio:>

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.990 [I] MeshForwarder-:     src:[fe80:0:0:0:c8e4:3d1:99a6:7688]:22

Jan 13 15:11:25 pulse-fox otbr-agent[295324]: 00:32:14.990 [I] MeshForwarder-:     dst:[fe80:0:0:0:ac1d:1c:86d:1da3]:58208

In Wireshark, we can see the outgoing TCP SYN message.
On the sever side, we can see the incoming TCP SYN message, and a TCP ACK message going back, which are both reflected in the log.

Yet, wireshark on the client side does not show the incoming TCP ACK message, and the application hangs, unable to establish a TCP connection.

Filtering the attached pcap shows the missing ACK packages.

Is there anything we could have misconfigured that prevents the client thread stack from forwarding the TCP ACK packages to the upper layers?
wireshark.zip

[jwhui]

One thing to check is whether OpenThread's TCP implementation is disabled in your build:

• https://github.com/openthread/ot-br-posix/blob/8bdfb6bc8bcc6418b54090b7db613ff93eb19a2b/third_party/openthread/CMakeLists.txt#L71

OpenThread's TCP implementation can intercept TCP packets that were intended for the host.

[dakhnod]

That seems to do the trick, thank you!