kvm-网络基础和网络相关命令的介绍

1、基础知识

1.1、网络模型

1.1.1、kvm网络模型介绍【nat和bridge】

kvm类型的虚拟机，默认情况下使用的是nat网络，同一网络模型下创建的多虚拟机之间可以彼此通信，这种网络模型与外界网络进行通信依赖于nat服务，nat服务正常的话，
该模型的网络是通过数据包的转换来达到通信的效果的，在网络流量比较大的场景下，该模式的网络模型会成为虚拟机的瓶颈。

生产中我们一般采用桥接的网络模型，这种模型是借助于宿主机的网卡设备，直接与外网进行通信，效果很好。

 

1.1.2、网络模型图

1.2、网络配置方式

对于kvm来说，它有两种网络：永久网络和临时网络

1.3、配置流程

前提：保证宿主机网络正常，网络服务使用network
首先：生成新的桥接设备
其次：关联桥设备和物理网卡设备
然后：清空物理网卡地址，启用桥设备地址，设置网络网关为桥设备地址
最后：虚拟机使用桥设备

2、实战

2.1、基本配置

2.1.1、kvm的网络配置目录位置

# tree /etc/libvirt/qemu/networks/
/etc/libvirt/qemu/networks/
├── autostart
│   └── default.xml -> /etc/libvirt/qemu/networks/default.xml
└── default.xml

2.1.2、查看桥接网络

# ifconfig vnet0
vnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::fc54:ff:fef4:2dfc  prefixlen 64  scopeid 0x20<link>
        ether fe:54:00:f4:2d:fc  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2581  bytes 134596 (134.5 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

2.1.3、查看vrish所有网络相关命令

# virsh -h | grep net-
    net-autostart                  autostart a network
    net-create                     create a network from an XML file
    net-define                     define an inactive persistent virtual network or modify an existing persistent one from an XML file
    net-destroy                    destroy (stop) a network
    net-dhcp-leases                print lease info for a given network
    net-dumpxml                    network information in XML
    net-edit                       edit XML configuration for a network
    net-event                      Network Events
    net-info                       network information
    net-list                       list networks
    net-name                       convert a network UUID to network name
    net-start                      start a (previously defined) inactive network
    net-undefine                   undefine a persistent network
    net-update                     update parts of an existing network's configuration
    net-uuid                       convert a network name to network UUID
    net-port-list                  list network ports
    net-port-create                create a network port from an XML file
    net-port-dumpxml               network port information in XML
    net-port-delete                delete the specified network port

2.2、网络查看

2.2.1、查看网络列表

virsh net-list
virsh net-list --all

2.2.2、查看网络信息

# virsh net-info default
Name:           default
UUID:           178c4147-c955-4252-827d-84b4b78a65d1
Active:         yes
Persistent:     yes
Autostart:      yes
Bridge:         virbr0

2.2.3、查看网络配置

# virsh net-dumpxml default
<network connections='1'>
  <name>default</name>
  <uuid>178c4147-c955-4252-827d-84b4b78a65d1</uuid>
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65535'/>
    </nat>
  </forward>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:eb:07:52'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>