qemu起虚拟机的网络配置

Qemu与Tap接口的网络设置

最新推荐文章于 2025-09-25 19:30:52 发布

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博客介绍了在QEMU中设置网络的相关内容，包括用户模式网络和Tap网络。用户模式网络有一定限制，而Tap网络可克服这些限制，但需提前设置tap且以root权限运行qemu。还给出了设置和清理的步骤，以及使用DHCP服务器自动配置的方法。

来自https://gist.github.com/extremecoders-re/e8fd8a67a515fee0c873dcafc81d811c

Setting up Qemu with a tap interface

There are two parts to networking within QEMU:

The virtual network device that is provided to the guest (e.g. a PCI network card).
The network backend that interacts with the emulated NIC (e.g. puts packets onto the host's network).

Example: User mode network

User mode networking allows the guest to connect back to the outside world through TCP, UDP etc. ICMP Ping is not allowed. Also connections from host to guest are not allowed unless using port forwarding.

$ qemu-system-i386 -cdrom Core-current.iso -boot d -netdev user,id=mynet0,hostfwd=tcp::8080-:80 -device e1000,netdev=mynet0

-netdev user,id=mynet0,hostfwd=tcp::8080-:80

Create the user mode network backend having id mynet0. Redirect incoming tcp connections on host port 8080 to guest port 80. The syntax is hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport

-device e1000,netdev=mynet0

Create a NIC (model e1000) and connect to mynet0 backend created by the previous parameter

Example: Tap network

TAP network overcomes all of the limitations of user mode networking, but requires a tap to be setup before running qemu. Also qemu must be run with root privileges.

$ sudo qemu-system-i386 -cdrom Core-current.iso -boot d -netdev tap,id=mynet0,ifname=tap0,script=no,downscript=no -device e1000,netdev=mynet0,mac=52:55:00:d1:55:01

-netdev tap,id=mynet0,ifname=tap0,script=no,downscript=no

Create a tap network backend with id mynet0. This will connect to a tap interface tap0 which must be already setup. Do not use any network configuration scripts.

-device e1000,netdev=mynet0,mac=52:55:00:d1:55:01

Create a NIC (model e1000) and connect to mynet0 backend created by the previous parameter. Also specify a mac address for the NIC.

Setup

Create a bridge
```
 brctl addbr br0
```
Clear IP of eth0
```
 ip addr flush dev eth0
```
Add eth0 to bridge
```
 brctl addif br0 eth0
```
Create tap interface
```
 tunctl -t tap0 -u `whoami`
```
Add tap0 to bridge
```
 brctl addif br0 tap0
```

Make sure everything is up

 ifconfig eth0 up
 ifconfig tap0 up
 ifconfig br0 up

Check if properly bridged
```
 brctl show
```
Assign ip to br0
```
 dhclient -v br0
```

Cleanup

Remove tap interface tap0 from bridge br0
```
brctl delif br0 tap0
```
Delete tap0
```
tunctl -d tap0
```
Remove eth0 from bridge
```
brctl delif br0 eth0
```
Bring bridge down
```
ifconfig br0 down
```
Remove bridge
```
brctl delbr br0
```
Bring eth0 up
```
ifconfig eth0 up
```
Check if an IP is assigned to eth0, if not request one
```
dhclient -v eth0
```