QEMU and tap problems
Derrick Ryalls
ryallsd at gmail.com
Thu Sep 20 17:57:09 PDT 2007
On 9/20/07, Doug Poland <doug at polands.org> wrote:
>
> Hello,
>
> I've been following the various instructions I've found on the web in an
> attempt to get tap networking with qemu-devel-0.9.0s.20070802 and
> kqemu-kmod-1.3.0.p11_2 on 6.2-STABLE.
>
> qemu was compiled with:
> _OPTIONS_READ=qemu-devel-0.9.0s.20070802
> WITH_KQEMU=true
> WITHOUT_HACKS_CIRRUS=true
> WITHOUT_RTL8139_TIMER=true
> WITHOUT_SAMBA=true
> WITH_SDL=true
> WITH_CDROM_DMA=true
>
> The kernel modules are loaded:
> if_tap, bridge, aio, kqemu
>
> The sysctls are changed:
> sysctl net.link.ether.bridge_cfg=ath0,tap0
> sysctl net.link.ether.bridge.enable=1
>
> The tap device exists:
> crw------- 1 root wheel 0, 134 Sep 19 22:42 /dev/tap0
>
> tap0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> inet 0.0.0.0 netmask 0xff000000 broadcast 0.255.255.255
> ether 00:bd:01:3c:01:00
> Opened by PID 1317
>
> The qemu-ifup script exists:
> cat /etc/qemu-ifup
> #!/bin/sh
> ifconfig ${1} 0.0.0.0
>
> I launch qemu like this:
> qemu -m 512 -localtime -hda VMs/w2k3.img -net nic -net tap
>
>
> Windows Server 2003 comes up. If I attempt to use DHCP to configure the
> interface in W2K3, I get a several minute pause while it attempts to
> contact a DHCP server, finally it fails with the message:
> "This connection has limited or no connectivity"
> and windows assigns itself the 169.254.244.101 address.
>
> If I try to manually configure the windows interface, i.e.,
> IP: 172.16.1.15
> NM: 255.255.255.0
> DG: 172.16.1.1
> NS: 172.16.1.17
> NS: 172.16.1.21
>
> Windows thinks it has connectivity, but I cannot ping the default
> gateway from the guest and I cannot ping the IP of the guest from the
> host.
>
> So at this point, I have no networking from the guest OS. About the
> only thing that I haven't seen on the web is people using wireless NICs
> in the host. In my case, I have an atheros chipset connected via WPA2
> to my WAP.
>
> All help is appreciated...
>
I just got tap working with an earlier build of qemu using clues from this site:
http://forums.bsdnexus.com/viewtopic.php?id=1563
Also, I can only get it working when I run it with sudo at the moment
and I have only tried with a wired nic. I have read in some places
that encryption causes problems with tap, but I don't have a link to
where I read it.
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