原因：在新安装的Linux系统中，防火墙默认是被禁掉的，一般也没有配置过任何防火墙的策略，所有不存在/etc/sysconfig/iptables文件。 解决办法：
、随便写一条iptables命令配置个防火墙规则：如： iptables -P OUTPUT ACCEPT ，进行保存 service iptables save ，service iptables restart 异常 The service command supports only basic LSB actions (start, stop, restart, try-restart, reload, force-reload, status). For other actions, please try to use systemctl. 解决 With RHEL / CentOS , firewalld was introduced to manage iptables. IMHO, firewalld is more suited for workstations than for server environments. It is possible to go back to a more classic iptables setup. First, stop and mask the firewalld service: [html] view plain copy
systemctl stop firewalld
systemctl mask firewalld Then, install the iptables-services package: [html] view plain copy
yum install iptables-services Enable the service at boot-time: [html] view plain copy
systemctl enable iptables Managing the service [html] view plain copy
systemctl stop iptables systemctl start iptables systemctl |restart iptables Saving your firewall rules can be done as follows: [html] view plain copy
service iptables save or [html] view plain copy
/usr/libexec/iptables/iptables.init save 参考文章：
http://www.centoscn.com/CentosBug/osbug/2014/0919/3779.html http://www.cnblogs.com/love3556/p/5923392.html