Linux Open firewall port and view, turn on related port number

firewall on and off (effective immediately, fail after reboot):

$ sudo service iptables start #开启 $ sudo service iptables stop #关闭

firewall on and off (takes effect after reboot):

$ sudo chkconfig iptables on$ sudo chkconfig iptables off

To open the relevant port :

Modify the/etc/sysconfig/iptables file to add the following:

-A input-p tcp-m state--state new-m TCP--dport 22-j ACCEPT

After modifying the iptables, restart the firewall to take effect:

$ sudo service iptables restart

-A: Add a rule to the rule chain input

INPUT: Rule Chain

-P: Represents the Packet usage protocol followed by TCP, which indicates the use of the TCP protocol

-M: Indicates an explicit match extension followed by state, indicating that the state module is explicitly loaded and used. New represents the state value of the status. The next-m TCP--dport 22 means explicitly loading the TCP module and specifying a matching condition of 22 for the target port.

-j ACCEPT: Specifies the target (action), which means to continue processing the grouping.

to view UDP-type ports :

$ NETSTAT-NUPL #UDP类型的端口

to view a port of type TCP :

$ NETSTAT-NTPL #TCP类型的端口

Use the lsof command to see if a port is open :

$ lsof-i:80

Take Port 80 as an example, if a display description is already open, it will not open if no instructions are displayed.

Linux Open firewall port and view, turn on related port number