[root@master tmp]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 5.1 (Santiago)
[root@master tmp]# service iptables start
iptables: No config file.                                  [WARNING]
[root@master tmp]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
num  target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination

[root@master tmp]# service iptables stop
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]

vim /etc/sysconfig/iptables

-- 永久性生效，重启后不会复原
chkconfig iptables on  #开启
 
chkconfig iptables off  #关闭
 
-- 即时生效，重启后复原
service iptables stop --停止
service iptables start --启动