listen fastopen

[beatnut]

Hello,
Does anybody know what this warning which i found in the docs
http://nginx.org/en/docs/http/ngx_http_core_module.html#listen  in the
context of fastopen means?

"Do not enable this feature unless the server can handle receiving the  same
SYN packet with data more than once."

My kernel is 4.9.9  and cat /proc/sys/net/ipv4/tcp_fastopen is 3 so this
feature is supported. Is this enought ?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,274066,274066#msg-274066