How do I create a wifi network bridge with qemu on OS X?
- by a paid nerd
I grabbed a small FreeBSD live CD and QEMU, and I'm trying to bridge my Mac OS X 10.8 wifi connection so that the guest OS is available on my LAN. However, the guest OS never gets a DHCP lease.
This works perfectly with VirtualBox in their "bridged" network mode, so I know it can be done. I need to get it working with QEMU because VirtualBox doesn't support the architecture that I need for this project.
Here's what I've done so far based on hours of googling:
Installed TUNTAP for OS X
Told OS X to supposedly forward all packets, even ARP: (NOTE: This doesn't appear to work.)
$ sudo sysctl -w net.inet.ip.forwarding=1
$ sudo sysctl -w net.link.ether.inet.proxyall=1
$ sudo sysctl -w net.inet.ip.fw.enable=1
Created a bridge:
$ sudo ifconfig bridge0 create
$ sudo ifconfig bridge0 addm en0 addm tap0
$ sudo ifconfig bridge0 up
$ ifconfig
bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether ac:de:xx:xx:xx:xx
Configuration:
priority 0 hellotime 0 fwddelay 0 maxage 0
ipfilter disabled flags 0x2
member: en0 flags=3<LEARNING,DISCOVER>
port 4 priority 0 path cost 0
member: tap0 flags=3<LEARNING,DISCOVER>
port 8 priority 0 path cost 0
tap0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
ether ca:3d:xx:xx:xx:xx
open (pid 88244)
Started tcpdump with -I in the hopes that it enables promiscuous mode on the wifi device:
$ sudo tcpdump -In -i en0
Run QEMU using the bridged network instructions:
$ qemu-system-x86_64 -cdrom mfsbsd-9.2-RELEASE-amd64.iso -m 1024 \
-boot d -net nic -net tap,ifname=tap0,script=no,downscript=no
But the guest system never gets a DHCP lease:
If I tcpdump -ni tap0, I see lots of traffic from the wireless network. But if I tcpdump -ni en0, I don't see any DHCP traffic from the QEMU guest OS.
Any ideas?
Update 1: I tried sudo defaults write "/Library/Preferences/SystemConfiguration/com.apple.Boot" "Kernel Flags" "net.inet.ip.scopedroute=0" and rebooting per this mailing list suggestion, but this didn't help. In fact, it made VirtualBox bridged mode stop working.
