letsencrypt的免费SSL证书续签及解决办法
正常letsencrypt的免费SSL证书续签, 常常需要停止nginx
步骤：
就是先停nginx服务，然后续签操作，在服务器上即：
1. 直接续签证书
find / -name "certbot-auto"
/root/letsencrypt/certbot-auto
/root/certbot-auto
/root/letsencrypt/certbot-auto/certbot-auto renew --force-renew --no-self-upgrade
--force-renew 强制更新
--no-self-upgrade 不更新 letsencrypt
2. 续签证书失败（重新注册证书）
执行： /root/letsencrypt/certbot-auto certonly --standalone --no-self-upgrade -d xxxxx.com
若执行报以下错
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for xxxx.com
Cleaning up challenges
Problem binding to port 80: Could not bind to IPv4 or IPv6.
停止nginx
sudo /usr/sbin/nginx -s stop
启动nginx
nginx -c /etc/nginx/nginx.conf
nginx -s reload
最后 用2生成的新的 fullchain.pem 和privkey.pem 替换原来旧的，即可
cp /etc/letsencrypt/live/xxx.com-0001/fullchain.pem /etc/letsencrypt/live/xxx.com/fullchain.pem
cp /etc/letsencrypt/live/xxx.com-0001/privkey.pem /etc/letsencrypt/live/xxx.com/privkey.pem
sudo /usr/sbin/nginx -t
sudo /usr/sbin/nginx -s reload
访问网站， 可以看到证书已续签 ！！
letsencrypt配置https 相关网址：
https://www.jianshu.com/p/0d455c7a9326
https://www.jianshu.com/p/e4def1f789c1
