1、systemctl enalble NetworkManager-wait-online.service 由于这个服务没有开启导致下面错误
network[798]: Bringing up loopback interface: Could not load file '/etc/sysconfig/network- scripts/ifcfg-lo'
network[798]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
network[798]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
network[798]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
2、当在vmware中无法访问外网时，由于没有关闭系统防火墙的原因：chkconfig iptables off
