命令行安装kvm虚拟机、桥接网络、用virt-manager管理
宿主机CentOS Linux release 7.2.1511 (Core)，内核3.10.0-327.el7.x86_64
1、配置宿主机网络桥接
想让虚拟机有自己的ip且外网可访问，需要在安装虚拟机前配置宿主机网络（桥接BRIDGE）：
在目录/etc/sysconfig/network-scripts下，将原始的ifcfg-enp2s0重命名ifcfg-enp2s0.old当备份，然后新建ifcfg-enp2s0内容如下：
TYPE=Ethernet
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
NAME=enp2s0
DEVICE=enp2s0
ONBOOT=yes
BRIDGE=br0
NM_CONTROLLED=no
再新建ifcgf-br0内容如下：
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br0
DEVICE=br0
NM_CONTROLLED=no
ONBOOT=yes
IPADDR=223.129.0.xxx
PREFIX=25
GATEWAY=223.129.0.xxx
DNS1=8.8.8.8
IPV6_PRIVACY=no
ZONE=public
重启网络：systemctl restart network
有时候会报错：
Restarting network (via systemctl): Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
可以通过journalctl -xe查看具体原因，我这里和该文http://blog.51cto.com/addam/1839518问题类似，所以通过：systemctl stop NetworkManager，然后再重启网络解决了...
ifconfig看到如下信息（要是不对可以尝试重启机器...）
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 223.129.0.xxx netmask 255.255.255.xxx broadcast 223.129.0.xxx inet6 fe80::4a5b:39ff:fea4:3ef0 prefixlen 64 scopeid 0x20<link> ether 48:5b:39:a4:3e:f0 txqueuelen 0 (Ethernet) RX packets 4016129 bytes 379659216 (362.0 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 7392459 bytes 11078132347 (10.3 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fe80::4a5b:39ff:fea4:3ef0 prefixlen 64 scopeid 0x20<link> ether 48:5b:39:a4:3e:f0 txqueuelen 1000 (Ethernet) RX packets 4260879 bytes 791804516 (755.1 MiB) RX errors 0 dropped 1092 overruns 0 frame 0 TX packets 7528373 bytes 11088764715 (10.3 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2、命令行安装kvm虚拟机
安装必要的软件这里就不说了...
ubuntu下（前两条用于安装，第三条用于启动）：
1 qemu-img create -f qcow2 /home/kvm/centos7-1511.img 20G
2 qemu-system-x86_64 -m 2048 -enable-kvm -hda /home/kvm/centos7-1511.img -cdrom /home/isos/CentOS-7-x86_64-DVD-1511.iso -boot d
3 qemu-system-x86_64 -enable-kvm -m 1024 -boot menu=on /home/kvm/centos7-1511.img
centos下：
1 qemu-img create -f qcow2 /home/kvm/centos7-1511.img 20G
2 /usr/libexec/qemu-kvm -m 2048 -enable-kvm -hda /home/kvm/centos7-1708.img -cdrom /home/isos/CentOS-7-x86_64-DVD-1511.iso -boot d
3 /usr/libexec/qemu-kvm -enable-kvm -m 1024 -boot menu=on /home/kvm/centos7-1511.img
如果用ubuntu下的命令2在centos下运行，会出现问题：
1、bash: qemu-system-x86_64: 未找到命令...
解决：qemu-system-x86_64是在安装qemu（注意不是qemu-kvm）时生成的命令，而centos下默认安装的是qemu-kvm包，对应的命令是qemu-kvm。通过rpm -ql qemu-kvm查看输出：/usr/libexec/qemu-kvm，用此替换得到centos下正确的命令2。
正确命令2运行后，输出信息是：
2、VNC server running on `::1:5900'
解决：在xshell下运行：vncviewer :5900，会出现
....
Can't open display:
所以用vncviewer连接到目标主机，然后在图形界面下运行vncviewer :5900，即会跳出安装centos的界面，顺着安装即可（记得在SOFTWARE SELECTION选择要最小安装还是图形界面）
3、让virt-manager可以管理刚才新建的虚拟机
运行完上述的命令1和2后，如果不想每次都通过命令3启动虚拟机，可以通过libvirt管理（这样以后直接virsh start 虚拟机名，即可开启虚拟机）
libvirt（包括virsh）使用xml文件对虚拟机进行配置，其中包括虚拟机名称、分配内存、vcpu等多种信息
下面是一个名为centos7-1511.xml的xml文件，其中定义了一个名为centos7-1511的kvm虚拟机（如果是32位要写i686）
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<name>centos7-1511</name>
<uuid>af939aef-c0eb-4b83-96ca-c23aecd3e057</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
<boot dev='hd'/>
<bootmenu enable='yes'/>
<bios useserial='yes' rebootTimeout='0'/>
</os>
<features>
<acpi/>
<apic/>
</features>
<cpu mode='custom'>
<model fallback='allow'></model>
</cpu>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/libexec/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/home/kvm/centos7-1511.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</disk>
<disk type='block' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hda' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<interface type='network'>
<mac address='48:5b:39:a4:3e:f1'/>
<source network='default'/>
<model type='e1000'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target port='0'/>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<input type='tablet' bus='usb'/>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='cirrus' vram='16384' heads='1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</memballoon>
</devices>
</domain>
然后运行下面的命令即可通过virt-manager管理名为centos7-1511的kvm虚拟机
1 [root@localhost kvm]# virsh define centos7-1511.xml 定义域 centos7-1511（从 centos7-1511.xml） 2 [root@localhost kvm]# virsh list --all Id 名称 状态 ---------------------------------------------------- - centos7-1511 关闭 3 [root@localhost kvm]# virsh start centos7-1511 域 centos7-1511 已开始
命令3可能会有问题：
[root@localhost kvm]# virsh start centos7-1511
错误：开始域 centos7-1511 失败
错误：internal error: process exited while connecting to monitor: qemu-kvm: -machine pc-i440fx-2.0,accel=kvm,usb=off,dump-guest-core=off: Unsupported machine type
Use -machine help to list supported machines!
通过以下命令：
[root@localhost kvm]# /usr/libexec/qemu-kvm -machine help
Supported machines are:
none empty machine
pc RHEL 7.0.0 PC (i440FX + PIIX, 1996) (alias of pc-i440fx-rhel7.0.0)
pc-i440fx-rhel7.0.0 RHEL 7.0.0 PC (i440FX + PIIX, 1996) (default)
rhel6.6.0 RHEL 6.6.0 PC
rhel6.5.0 RHEL 6.5.0 PC
rhel6.4.0 RHEL 6.4.0 PC
rhel6.3.0 RHEL 6.3.0 PC
rhel6.2.0 RHEL 6.2.0 PC
rhel6.1.0 RHEL 6.1.0 PC
rhel6.0.0 RHEL 6.0.0 PC
将xml文件中machine部分替换，然后通过下面的undefine命令取消刚才的虚拟机，再重新运行上面的define即可
可通过:
virsh undefine centos7-1511取消定义虚拟机，之后系统无法识别centos7-1511（此步骤与virsh define centos7-1511.xml对应）
virsh destroy centos7-1511直接销毁虚拟机，取消定义，之后无法执行undefine
注意：用virt-manager第一次启动虚拟机时别忘了修改为桥接，否则即使你在虚拟机里配置了ip等信息，ping网关啥的都会出现：Destination Host Unreachable
4、虚拟机网络配置
修改网络配置文件：
1、ubuntu虚拟机中修改网络配置文件（因为有时候图形界面操作时，会出现无法save的情况）
修改/etc/network/interfaces文件为：
# eth0是你虚拟机的网卡，可以通过ifconfig查看 auto eth0 iface eth0 inet static #ip address 223.129.0.xxx # 子网和网关 netmask 255.255.255.xxx gateway 223.129.0.xxx
修改/etc/resolvconf/resolv.conf.d/base文件，设置dns
nameserver 8.8.8.8
重启虚拟机，通过ifconfig看到信息：
eth0 Link encap:Ethernet HWaddr 52:54:00:7c:da:c9 inet addr:223.129.0.xxx Bcast:223.129.0.xxx Mask:255.255.255.xxx inet6 addr: fe80::5054:ff:fe7c:dac9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:219111 errors:0 dropped:0 overruns:0 frame:0 TX packets:9266 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:31389489 (31.3 MB) TX bytes:761327 (761.3 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:64 errors:0 dropped:0 overruns:0 frame:0 TX packets:64 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1 RX bytes:5632 (5.6 KB) TX bytes:5632 (5.6 KB)
此时用xshell连接，会出现connection failed
因为ubuntu虚拟机中必须安装openssh-server软件，这样才可以通过ssh连接
安装命令：
1 sudo apt-get install openssh-server 2 sudo /etc/init.d/ssh restart //重启ssh服务
安装好后，用以下命令查看22端口是否处于LISTEN状态，如果是，则说明已经配置好了ubuntu的ssh服务
root@jin:/home/jin# netstat -ntlp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 2645/sshd
2、centos下
这个没试，下面是通过图形界面配置后，相应文件内容
[root@localhost network-scripts]# pwd
/etc/sysconfig/network-scripts
[root@localhost network-scripts]# cat ifcfg-ens3
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="ens3"
UUID="3b886635-d2a9-4569-9763-7468890a64d8"
DEVICE="ens3"
ONBOOT="yes"
DNS1="8.8.8.8"
IPADDR=223.129.0.xxx
PREFIX=25
GATEWAY=223.129.0.xxx
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_PRIVACY=no
补充
1、桥接和NAT
。。。。
2、创建虚拟机时各命令含义
。。。。占坑之后写
3、libvirt
。。。
