I just had a short romance with RST/ACK. It happened during a keepalive http session to AWS ELB, where the nginx backend had keepalive disabled completely due

I just had a short romance with RST/ACK. It happened during a keepalive http session to AWS ELB, where the nginx backend had keepalive disabled completely due to a misconfiguration. The ELB's idle_time was set to 10seconds (instead of default 60). Just because the idle_time was set to a low value the effect of seeing the RST/ACK could be seen. It needed Wireshark to track this down. On the http level it appeared that a request had been sent, but the received response was empty and didn't even reach nginx at all (because ELB closed the stream).