I have a ubuntu 13.04 server. On it I have a virtual machine (kvm), with Windows 2008 on it.

I have configured /etc/network/interfaces to have a bridged connection to the machine, so I am able to access my MS SQL databases on said virtual machine.

However, I am still not able to connect to it. What am I doing wrong?

Here is my current /etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto br0
iface br0 inet static
    bridge_ports eth0
    bridge_stp off
    bridge_maxwait 5

I notice when I shell into the server that this IP is not listed, but a virbr0 interface with a different IP address is listed.

Note, I have the virtual machine configured to use the bridge. The virtual machine comes up with for an IP address, however, when I try to ping it from the host, nothing comes back as well. (if this helps any)

  • is eth0 a wired or wireless interface? don't expect bridging to work correctly on wifi. – Luke404 May 2 '13 at 18:08
  • eth0 is wired interface – Kevin May 2 '13 at 18:40

If you ping the host with no response, the I suggest you check the following:
1. Did you turn on Window Firewall ?
2. Did you turn on Ubuntu Firewall/iptables?
3. Check the subnet setting in Windows
4. try to issue arp in Window command line and see if you can get the MAC address, of the router and of the Linux Box.
5. if the MAC address of Window and the Linux Box collide ?
6. the network card off-load options, <- try to disable them. (especially inside the Window VM).

enter image description here

  • i cannot ping host from client, nor client from host. It's a default install of win2k8 r2, so I imagine that wf is already enabled. 2. no, 3.all set, 4. no conflicting MAC, 5.no, 6. huh? – Kevin May 2 '13 at 18:44
  • also, for some reason or another, the network on the client loses it's connection every one in awhile – Kevin May 2 '13 at 19:09
  • that connection dropping issue... i noticed that when I am surfing the net it does not drop, but if I say, try to copy a file that's over 200M from a networked drive, the connection drops. I wonder something also, the physical machine has another nic in it, that I currently do not have an ethernet cable for, if I get one and plug it in, and then force the VM to use that, will this issue be cured? – Kevin May 2 '13 at 20:16
  • i have post a picture about the network card offload if you have no idea what is it. It is some features of network card driver which put the loading , calculation of network stack into the network card hardware. Since the VM lan card didn't have real hardware. So it could, either virtualize it, or even worst, put them to the real lan card. normally offload to real lan card won't cause problems, except the situation of loop back traffic, just like your case. for which the network hardware may mis-perform, since they are not suppose to design with loop back hardware call – user170531 May 3 '13 at 17:38
  • but virtualize the offload mechanism is even worst, since those are actually hardware implementation which is quite differ from how CPU works. There won't be problem if moving slow, but the default copy speed between the vm and physical box is unlimited, thus it will result buffer overflow easily. – user170531 May 3 '13 at 17:40

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