How to open a port in centos?

How to open a port in centos?

How to open a port in centos:

1. iptables (centos 6 and before)

1. Turn on/off/restart the firewall

Turn on the firewall (it will take effect permanently after restarting):chkconfig iptables on

Turn off the firewall (it will take effect permanently after restarting):chkconfig iptables off

Turn on the firewall (effective immediately, invalid after restart): service iptables start

Turn off the firewall (effective immediately, invalid after restart): service iptables stop

Restart the firewall: service iptables restartd

2. Check the open ports

/etc/init.d/iptables status

3. Open a certain port (take 8080 as an example)

(1) Open the port

iptables -A INPUT -p tcp --dport 8080 -j ACCEPT

(2) Save and restart the firewall

/etc/rc.d/init.d/iptables save
/etc/init.d/iptables restart

4. Open the port between 49152~65534

iptables -A INPUT -p tcp --dport 49152:65534 -j ACCEPT

Similarly, Here you need to save the settings and restart the firewall.

5. Other opening methods

We can also open the port by modifying the /etc/sysconfig/iptables file, as follows

vi /etc/sysconfig/iptables

and then in Add a line to the file

-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 8080 -j ACCEPT

Parameter description:

–A The parameter is regarded as adding a rule

–p specifies what protocol it is, our commonly used tcp protocol, of course There are also udp, for example, DNS

-dport of port 53 is the target port. When data enters the server from the outside, it is the target port

-sport. When data goes out of the server, it is the data source port.

–j means to specify ACCEPT - to receive or DROP not to receive

2. firewalld (centos7)

Centos7 has firewalld installed by default, if it is not installed , can be installed using yum install firewalld firewalld-config.

1. Start the firewall

systemctl start firewalld

2.Disable the firewall

systemctl stop firewalld

3.Set the startup

systemctl enable firewalld

4.Stop and disable the startup

sytemctl disable firewalld

5. Restart the firewall

firewall-cmd --reload

6. Check the status

systemctl status firewalld或者 firewall-cmd --state

7. Check the version

firewall-cmd --version

8. Check the help

firewall-cmd --help

9. Check the area information

firewall-cmd --get-active-zones

10. Check the area information to which the specified interface belongs

firewall-cmd --get-zone-of-interface=eth0

11. Reject all packets

firewall-cmd --panic-on

12. Cancel the rejection status

firewall-cmd --panic-off

13 .Check whether it is rejected

firewall-cmd --query-panic

14.Add the interface to the zone (the default interfaces are all in public)

firewall-cmd --zone=public --add-interface=eth0(永久生效再加上 --permanent 然后reload防火墙)

15.Set the default interface zone

firewall-cmd --set-default-zone=public(立即生效，无需重启)

16.Update the firewall rules

firewall-cmd --reload或firewall-cmd --complete-reload(两者的区别就是第一个无需断开连接，就是firewalld特性之一动态
添加规则，第二个需要断开连接，类似重启服务)

17. View all open ports in the specified area

firewall-cmd --zone=public --list-ports

18. Open ports in the specified area (remember to restart the firewall)

firewall-cmd --zone=public --add-port=80/tcp(永久生效再加上 --permanent)

Recommended tutorial: "centos Tutorial》

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