启用https提高网站安全性

细心的老读者可能发现，本站现在全面启用了https，为啥捏？因为好看！哇哈哈哈……

这里记录一下Centos6系统上的nginx配置方法。这里我使用 letsencrypt 提供的免费证书，首先访问https://certbot.eff.org/，然后根据你的实际情况选择webserver和操作系统，这里为了通用性，我选择“Unspecified Webserver on Other UNIX”。

首先下载脚本并添加执行权限：

wget https://dl.eff.org/certbot-auto
chmod a+x certbot-auto

停止nginx或其他占用80端口的服务后执行：./certbot-auto certonly

会弹出一个文本方式的UI界面，这里为了方便我选择第二项：

Automatically use a temporary webserver (standalone)

然后根据提示一步步的填写邮箱、域名（多个之间使用逗号或者空格分割）后看见下面的提示就代表成功了：

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at
   /etc/letsencrypt/live/xxx.com/fullchain.pem. Your cert will
   expire on 2016-09-21\. To obtain a new or tweaked version of this
   certificate in the future, simply run certbot-auto again. To
   non-interactively renew *all* of your certificates, run
   "certbot-auto renew"
 - If you lose your account credentials, you can recover through
   e-mails sent to xxxx@xxx.com.
 - Your account credentials have been saved in your Certbot
   configuration directory at /etc/letsencrypt. You should make a
   secure backup of this folder now. This configuration directory will
   also contain certificates and private keys obtained by Certbot so
   making regular backups of this folder is ideal.
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

紧接着编辑nginx的配置文件：

server
    {
        listen 80 default;
        server_name _;
        rewrite ^(.*) https://dear-shen.com/ permanent;
    }
server
    {
        listen 443 ssl;
        server_name dear-shen.com www.dear-shen.com;

        ssl_certificate /etc/letsencrypt/live/dear-shen.com/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/dear-shen.com/privkey.pem;

        #省略部分配置....
    }

根据你的实际情况进行修改后，重启nginx服务即可。如果启用用了防火墙的话，注意开放443端口。

另外记住，这个证书只有90天的有效期，需要自己进行手动刷新。方法也很简单首先停止nginx等占用80端口的服务后执行：

./path/to/certbot-auto renew --dry-run

如果上述命令执行正常的话，也可以设定计划任务执行：

./path/to/certbot-auto renew --quiet --no-self-upgrade