https://blog.csdn.net/aienjoy/article/details/78994128
1.Down:ifconfig virbr0 down2.Delete:brctl delbr virbr03.virbr0是由libvirtd服务创建,libvirtd在guest里没啥卵用,所以干掉它,不然下次启动又创建了:systemctl disable libvirtd