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=<UP,BROADCAST,RUNNING,MULTICAST>  mtu
        inet 223.129.0.xxx  netmask 255.255.255.xxx  broadcast 223.129.0.xxx
        inet6 fe80::4a5b:39ff:fea4:3ef0  prefixlen   scopeid 0x20<link>
        ether :5b::a4:3e:f0  txqueuelen   (Ethernet)
        RX packets   bytes  (362.0 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (10.3 GiB)
        TX errors   dropped  overruns   carrier   collisions
enp2s0: flags=<UP,BROADCAST,RUNNING,MULTICAST>  mtu
        inet6 fe80::4a5b:39ff:fea4:3ef0  prefixlen   scopeid 0x20<link>
        ether :5b::a4:3e:f0  txqueuelen   (Ethernet)
        RX packets   bytes  (755.1 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (10.3 GiB)
        TX errors   dropped  overruns   carrier   collisions  

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 :::7c:da:c9
          inet addr:223.129.0.xxx  Bcast:223.129.0.xxx  Mask:255.255.255.xxx
          inet6 addr: fe80:::ff:fe7c:dac9/ Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:  Metric:
          RX packets: errors: dropped: overruns: frame:
          TX packets: errors: dropped: overruns: carrier:
          collisions: txqueuelen:
          RX bytes: (31.3 MB)  TX bytes: (761.3 KB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::/ Scope:Host
          UP LOOPBACK RUNNING  MTU:  Metric:
          RX packets: errors: dropped: overruns: frame:
          TX packets: errors: dropped: overruns: carrier:
          collisions: txqueuelen:
          RX bytes: (5.6 KB)  TX bytes: (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：

 sudo apt-get install openssh-server
 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:              0.0.0.0:*               LISTEN      /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

。。。