設置SSH只允許指定IP才能訪問

vim /etc/hosts.allow

sshd:192.168.31.109:allow //只允許192.168.31.109登錄
vim /etc/hosts.deny

sshd:ALL //開啓白名單，只允許192.168.31.109登錄
systemctl restart sshd ，重啓sshd