Linux releases designated ports

1. Check firewall status

firewall-cmd --state
# 若是running，说明防火墙已经开启
# 若是not running需执行命令：systemctl start firewalld.service

2. Check whether the port is allowed

firewall-cmd --query-port=端口号/tcp

3. Release the designated port

firewall-cmd --zone=public --add-port=端口号/tcp --permanent

4. Restart the firewall

systemctl restart firewalld.service
firewall-cmd --reload