change port of sshd at CentOS 7

vi /etc/ssh/sshd_config

firewall-cmd --permanent --zone=public --add-port=xxx/tcp

firewall-cmd --reload

systemctl restart sshd.service

when failed to restart,

yum install policycoreutils-python

semanage port -a -t ssh_port_t -p tcp xxxx

systemctl restart sshd.service