通过“开启SSH服务”学习Linux软件包和服务的管理

# 开启SSH服务
## install openssh-server
### pre
* apt list --installed
* apt update
### apt install openssh-server
## manage service
### service eg:
* service --status-all
* service ssh stop
### systemctl eg:
* systemctl status ssh
* systemctl restart ssh
## config SSH
### /etc/ssh/sshd_config