qemu起虚拟机的网络配置

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

dhclient - Auto configuration using a DHCP server

Release IP

dhclient -v -r <interface>

Request IP

dhclient -v <interface>