certbot泛解析域名生成证书

sudo certbot --server https://acme-v02.api.letsencrypt.org/directory -d *.example.com --manual --preferred-challenges dns-01 certonly

selinux导致nginx proxy_pass错误

在centos7上配置nginx反向代理，502错误，查看error.log，错误如下：

 connect() to 127.0.0.1:9999 failed (13: Permission denied) while connecting to upstream

解决办法：

sudo setsebool -P httpd_can_network_connect on