View port usage and enable Port commands on Centos

Centos command to view port usage, for example, to view port 80 usage use the following command: lsof-itcp: 80 to list all port netstat-ntlp1, open port (take Port 80 as an example) Method 1: & Centos command to view port usage, for example, to view port 80 usage, use the following command: lsof-I tcp: 80 to list all ports netstat-ntlp 1. enable port (take Port 80 as an example) method 1:/sbin/iptables-I INPUT-p tcp -- dport 80-j ACCEPT write modification/etc/init. d/iptables save and modify service iptables restart to restart the firewall. Method 2: vi/etc/sysconfig/iptables open the configuration file and add the following statement: -a input-p tcp-m state -- state NEW-m tcp -- dport 80-j ACCEPT restart firewall. modification completed. 2. Method 1 is disabled: /sbin/iptables-I INPUT-p tcp -- dport 80-j DROP write modification/etc/init. d/iptables save and modify service iptables restart to restart the firewall. Method 2: vi/etc/sysconfig/iptables open the configuration file and add the following statement: -a input-p tcp-m state -- state NEW-m tcp -- dport 80-j DROP restart the firewall. the modification is complete. 3. check the port status/etc/init. d/iptables status