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1.2. qemu命令起虚拟机增加网络配置

news 2025/8/16 8:58:33

1. 网络配置

常见的网络模式分为tap网络和基础网络模式两种。

1.1. TAP网络（桥接模式）

虚拟机直接接入宿主机物理网络，获得独立IP

1.1.1. 使用tap方式起虚拟机网络

 -netdev tap,id=hostnet0,ifname=tap0 \-device virtio-net-pci,netdev=hostnet0 \

其中，-netdev中的id要和-device中的netdev值保持一致。自定义值

1.1.2. qemu启动示例

 /usr/bin/qemu-system-loongarch64  \-name guest=vm1 \-machine virt,accel=kvm   \-nodefaults  \-m 2048  \-smp 2,maxcpus=4,cores=4,threads=1,sockets=1   \-cpu 'la464-loongarch-cpu'  \-bios /usr/share/edk2/loongarch64/QEMU_EFI.fd    \-drive file=/home/OpenCloudOS-9.4.qcow2,if=virtio  \-nographic      \-serial stdio    \-netdev tap,id=hostnet0,ifname=tap0 \-device virtio-net-pci,netdev=hostnet0 \-monitor telnet:localhost:4445,server,nowait   \-msg timestamp=on

使用上述qemu命令启动虚拟机会提示缺少/etc/qemu-ifup文件，创建该文件并编写脚本

1.1.3. /etc/qemu-ifup文件编写

[root@bogon ~]# ls -lah /etc/qemu-ifup 
-rwxr-xr-x 1 root root 1.2K  8月 6日 10:11 /etc/qemu-ifup[root@bogon ~]# cat /etc/qemu-ifup 
#! /bin/sh
# Script to bring a network (tap) device for qemu up.
# The idea is to add the tap device to the same bridge
# as we have default routing to.# in order to be able to find brctl
PATH=$PATH:/sbin:/usr/sbin
ip=$(which ip)if [ -n "$ip" ]; thenip link set "$1" up
elsebrctl=$(which brctl)if [ ! "$ip" -o ! "$brctl" ]; thenecho "W: $0: not doing any bridge processing: neither ip nor brctl utility not found" >&2exit 0fiifconfig "$1" 0.0.0.0 up
fi#switch=$(ip route ls | \
#    awk '/^default / {
#          for(i=0;i<NF;i++) { if ($i == "dev") { print $(i+1); next; } }
#         }'
#        )
switch=virbr0# only add the interface to default-route bridge if we
# have such interface (with default route) and if that
# interface is actually a bridge.
# It is possible to have several default routes too
for br in $switch; doif [ -d /sys/class/net/$br/bridge/. ]; thenif [ -n "$ip" ]; thenip link set "$1" master "$br"elsebrctl addif $br "$1"fiexit # exit with status of the previous commandfi
doneecho "W: $0: no bridge for guest interface found" >&2

1.2. 基础网络模式（NAT模式）

适用于简单联网需求，虚拟机通过宿主机 NAT 访问外网。

1.2.1. 使用user模式起虚拟机

 -netdev user,id=net,hostfwd=tcp::2222-:22  \-device virtio-net-pci,netdev=net \

其中，-netdev中的id要和-device中的netdev值保持一致。自定义值

1.2.2. 完整的qemu启动命令

/usr/bin/qemu-system-loongarch64  \-name guest=vm1 \-machine virt,accel=kvm   \-nodefaults  \-m 2048  \-smp 2,maxcpus=4,cores=4,threads=1,sockets=1   \-cpu 'la464-loongarch-cpu'  \-bios /usr/share/edk2/loongarch64/QEMU_EFI.fd    \-drive file=/home/OpenCloudOS-9.4-test.qcow2,if=virtio  \-nographic      \-serial stdio    \-netdev user,id=net1,hostfwd=tcp::2222-:22  \-device virtio-net-pci,netdev=net1 \-monitor telnet:localhost:4448,server,nowait   \-msg timestamp=on

hostfwd=tcp::2222-:22 解析：将宿主机的2222端口转发到虚拟机的22端口（SSH）

1.2.3. 自定义局域网网段

自定义虚拟机网络为192.168.200.XX网段

 -netdev user,id=net1,net=192.168.200.0/24,hostfwd=tcp::2223-:22  \-device virtio-net-pci,netdev=net1 \

2. 问题记录

问题描述：使用上述两种方式在同一物理机上创建启动两个虚拟机，发现两个虚拟机中的ip一致
问题分析：分析问题发现，新创建启动的两个虚拟机中的MAC地址一样，故IP一致
解决方法：自定义虚拟机的MAC地址

TAP网络：

 -netdev tap,id=hostnet0,ifname=tap0 \-device virtio-net-pci,netdev=hostnet0,mac=52:54:00:12:34:54 \ -netdev tap,id=hostnet1,ifname=tap1 \-device virtio-net-pci,netdev=hostnet1,mac=52:54:00:12:34:56 \

基础网络：

 -netdev user,id=net1,net=192.168.200.0/24,hostfwd=tcp::2223-:22  \-device virtio-net-pci,netdev=net1,mac=52:54:00:12:34:54 \-netdev user,id=net1,net=192.168.200.0/24,hostfwd=tcp::2223-:22  \-device virtio-net-pci,netdev=net1,mac=52:54:00:12:34:56 \