No TCP ACK on first client request


Hello. I have HA-Proxy version 1.8.7.
I use curl --with-negotiate -x http://haproxy:3128 as client and Squid proxy as backend.

With haproxy i see this:

Why there is no TCP ACK packet between HEAD and HTTP with 407 code? Why haproxy don’t send TCP ACK on first client request?


Frame 5 probably ACKs frame 4. The wireshark per frame summary line is certainly not enough to understand this. Click on the frame, and open the TCP details of those specific packets.

That being said, haproxy does not manage the ACKs, your Operating System/kernel does.


This pcap dump file of traffic without HAProxy

And this of traffic through HAProxy

WIthout HAProxy there is empty TCP packet with ACK flag from server to client after TCP with first get


And with HAProxy this TCP packet absent


What I said: Frame 5 is ACKing Frame 4.

Just open frame 5, TCP and then go to SEQ/ACK analysis.