Linux basic firewall settings and open port commands


Turn off firewall

CentOS 7RedHat 7Firewall on and off in previous Linux distributions(iptables ):

Immediate effect, restartinvalid

service iptables start
#Shut down
service iptables stop

restarttake effect

chkconfig iptables on
#Shut down
chkconfig iptables off

CentOS 7RedHat 7Firewall on and off for subsequent Linux distributions(firewall ):

systemctl stop firewalld.service 

Open port

CentOS 7RedHat 7Previous Linux distributions open ports

#Command mode open 5212 port command

#Open port 5212 to receive data
/sbin/iptables -I INPUT -p tcp --dport 5212 -j ACCEPT

#Open port 5212 to send data
/sbin/iptables -I OUTPUT -p tcp --dport 5212 -j ACCEPT

#Save configuration
/etc/rc.d/init.d/iptables save

#Restart firewall service
/etc/rc.d/init.d/iptables restart

#Check whether it is opened successfully
/etc/init.d/iptables status

CentOS 7RedHat 7Subsequent Linux distributions open ports

firewall-cmd --zone=public --add-port=5121/tcp --permanent
#-- zone scope
#-- add port = 5121 / TCP add port, format: port / communication protocol
#-- permanent takes effect permanently. Without this parameter, it will become invalid after restart