http://tyy.host-ed.me/pluxml/article4/port-443-for-https-ssh-and-ssh-over-ssl-and-more

Proxy protocol:

http://wiki.bedis.eu/nginx/nginx_proxy_protocol_patch

http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt

https://chrislea.com/2014/03/20/using-proxy-protocol-nginx/

sslh:

https://github.com/yrutschle/sslh