O011、理解 virbr0

参考https://www.cnblogs.com/CloudMan6/p/5308071.html

 

virbr0 是KVM 默认创建的一个Bridge ，其作用是为该宿主机上的虚机提供NAT上网的功能。virbr0默认分配了一个IP地址 192.168.122.1 并为连接在上面的虚拟网卡提供DHCP服务。

 

下面我们演示如何使用 virbr0

 

创建虚机 VM3 ，并设置网卡连接到 NAT 网络中

 

 

root@ubuntu:~# virsh list    #    查看VM3运行状态

Id    Name                           State

----------------------------------------------------

10    VM3                            running

 

root@ubuntu:~# virsh domiflist VM3    #    查看VM3 虚机接口

Interface  Type       Source     Model       MAC

-------------------------------------------------------

vnet0      network    default    rtl8139     52:54:00:e3:0f:d2

 

root@ubuntu:~# brctl show    #    查看 VM3 虚机接口连接到了 virbr0 上

bridge name    bridge id        STP enabled    interfaces

br0        8000.005056874c70    no        ens160

virbr0        8000.fe5400e30fd2    yes        vnet0

 

root@ubuntu:~# ps -ef | grep dnsmasq    #    virbr0 使用 dnsmasq提供 DHCP服务

libvirt+  3803     1  0 21:58 ?        00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper

root      3804  3803  0 21:58 ?        00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper

root      6121  5694  0 23:03 pts/3    00:00:00 grep --color=auto dnsmasq

 

root@ubuntu:~# cat /var/lib/libvirt/dnsmasq/default.conf    #    DHCP 配置文件

##WARNING:  THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE

##OVERWRITTEN AND LOST.  Changes to this configuration should be made using:

##    virsh net-edit default

## or other application using the libvirt API.

##

## dnsmasq conf file created by libvirt

strict-order

user=libvirt-dnsmasq

pid-file=/var/run/libvirt/network/default.pid

except-interface=lo

bind-dynamic

interface=virbr0

dhcp-range=192.168.122.2,192.168.122.254

dhcp-no-override

dhcp-lease-max=253

dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile

addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

 

 

在虚机中进行网络连通性测试，DHCP或得的IP地址可以ping同宿主机和宿主机外面的网络