At last! In the past we had to recompile FreeBSD TCP stack on nginx frontend to change some constants like hardcorded first SYN timeout.

yep, unfortunately it will be a while before it gets into apt

If you're running nginx in production on Ubuntu or Debian, you'd probably be well-served by using their packages rather than the distribution default ones.

http://nginx.org/en/download.html

thanks, will look into that