Let’s Encrypt 的免费SSL证书一般通过服务器使用Certbot来进行自动注册更新和管理，但是centos 6系统却无法通过yum install certbot命令直接安装Certbot，会提示No package certbot available. 返回如下信息
代码语言：javascript复制Loaded plugins: fastestmirror
Setting up Install Process
Loading mirror speeds from cached hostfile
* base: mirrors.huaweicloud.com
* epel: mirrors.tuna.tsinghua.edu.cn
* extras: mirrors.njupt.edu.cn
* updates: mirror.bit.edu.cn
No package certbot available.正确的安装方法如下：
代码语言：javascript复制wget https://dl.eff.org/certbot-auto
sudo mv certbot-auto /usr/local/bin/certbot-auto
sudo chown root /usr/local/bin/certbot-auto
sudo chmod 0755 /usr/local/bin/certbot-auto其他系统安装certbot
代码语言：javascript复制### CentOS 7 / RHEL 7 ###
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
### Ubuntu / Debian ###
apt-get update
apt-get install software-properties-common
add-apt-repository ppa:certbot/certbot
apt-get update然后
代码语言：javascript复制### CentOS 7 / RHEL 7 ###
yum install certbot
### Ubuntu 16.04 / Debian 9 ###
apt-get install certbot
### Debian 8 ###
apt-get install certbot -t jessie-backports
