https://doujinblog.org/%e5%90%8c%e4%ba%bacg%e9%9b%86210409hardening-%e5%99%82%e3%81%ae%e5%bf%83%e9%9c%8a%e7%8f%be%e8%b1%a1%e3%82%92%e7%a2%ba%e3%81%8b%e3%82%81%e3%81%ab%e5%a4%9c%e3%81%ae%e5%ad%a6%e6%a0%a1%e3%81%ab/