自己的腾讯云服务器上跑了点小应用，本想着没什么内容就没必要弄 https了，但是同学还是强烈建议我加上去。之后用http访问没备案服务器会提示“该网站暂时无法访问”，https 的没有这个影响，不禁觉得加上 https 是个明智的选择。
## 安装
在网上找到的大部分是从源代码编译开始用的，找到一个 certbot ，是用 PPA 装的软件，方便不少。
https://certbot.eff.org/
以我自己的配置来说（Ubuntu 16.04 + Nginx），安装的命令是这样的：
$ sudo apt-get update
$ sudo apt-get install software-properties-common
$ sudo add-apt-repository ppa:certbot/certbot
$ sudo apt-get update
$ sudo apt-get install python-certbot-nginx
具体命令，在上面的链接中正确选择好就会显示。
## 配置
运行 ``` sudo letsencrypt certonly ```
提示
How would you like to authenticate with the ACME CA?
1: Spin up a temporary webserver (standalone)
2: Place files in webroot directory (webroot)
Select the appropriate number [1-2] then [enter] (press 'c' to cancel):
选择1
Please enter in your domain name(s) (comma and/or space separated) (Enter 'c' to cancel):
根据提示输入域名
出现类似于以下内容就是正确配置了
```
IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at
/etc/letsencrypt/live/domain.com/fullchain.pem. Your cert will
expire on 2017-10-13. To obtain a new or tweaked version of this
certificate in the future, simply run certbot again. To
non-interactively renew *all* of your certificates, run "certbot
renew"
- 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
生成2048位 DH parameters：
sudo openssl dhparam -out /etc/ssl/certs/dhparams.pem 2048
## 修改 Nginx 配置
在 /etc/nginx/sites-enabled 下新建文件，添加以下内容
server {
listen 443 ssl;
server_name domain.com;
ssl_certificate /etc/letsencrypt/live/domain.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/domain.com/privkey.pem;
ssl_dhparam /etc/ssl/certs/dhparams.pem;
ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-A ES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-S HA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS- AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-S HA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC 3-SHA';
ssl_prefer_server_ciphers on;
}
重启 Nginx 后即可生效。
