Connection reset during iperf test

[tjanker]

Hello together,

when I do an iperf test with OPNsense running on a Supermicro X11SBA-LN4F as server and an linux box as client, OPNsense sends a TCP reset after receiving some kBytes, see attached pcap.

The linux box and the firewall are connected via an managed HP OfficeConnect 1920S.

Additionally, when I try an iperf test between two linux boxes connected to different interfaces/subnets, I see TCP retransmissions on the client side after the same amount of initial data. OPNsense seems to stop forwarding the TCP packets.

Has anybody an idea why this happens?

regards,
Thomas

[JasMan]

Hey tjanker,

Your OPNsense ends the connection to the client by sending the FIN flag in packet 18. The the RST flag in packet 19 is only to shutdown the connection immediatly without any timeouts.

Have you used any iPerf options? Is IPS enabled?

I guess you've captured the traffic on the client, because the frames from the clients are bigger than 1518 bytes (offloading is active).
Can you do another capture "on the wire" or on a mirror port on the switch?

Jas