https://blog.toright.com/posts/3967/%e5%af%8c%e4%ba%ba%e7%94%a8-l4-switch%ef%bc%8c%e7%aa%ae%e4%ba%ba%e7%94%a8-linux-haproxy%ef%bc%81
富人用 L4 Switch,窮人用 Linux HAProxy!