CentOS：
# systemctl stop firewalld
# systemctl disable firewalld
Suse：
systemctl stop SuSEfirewall2.service
systemctl stop SuSEfirewall2_init.service
systemctl disable SuSEfirewall2.service
systemctl disable SuSEfirewall2_init.service
连接xshell都需要：
sed -i 's/PasswordAuthentication no/PasswordAuthentication yes/' /etc/ssh/sshd_config
# 启动 sshd 服务
systemctl restart sshd
systemctl enable sshd