CentOS 6:
1) 永久性生效,重启后不会复原
开启: chkconfig iptables on
关闭: chkconfig iptables off
2) 即时生效,重启后复原
开启: service iptables start
关闭: service iptables stop
CentOS 7:
systemctl start firewalld.service#启动firewall
systemctl stop firewalld.service#停止firewall
systemctl disable firewalld.service#禁止firewall开机启动
查询TCP连接情况:
netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a,S[a]}'
查询端口占用情况:
netstat -anp | grepportno(例如:netstat –apn | grep 80)