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-   -   setup dummy interface running DHCP and DNS for VM (

scheidel21 08-29-2007 12:46 PM

setup dummy interface running DHCP and DNS for VM
Ok here is the story, I am running a xen kernel with xen 3.1 and a 2.6.18 kernel. I am running an existing windows installation from a hard drive. This is on a laptop, and I am attempting to get networking setup for the windows vm. If I connect my laptop via the ethernet port and set the appropriate netdev=eth1 in the xend setup the xen networking scripts work fine and I get networking for both the VM(domU) and the the dom0. But since this is a laptop I do not have it connected all the time via wired interface, as a test I changed the netdev to wlan0 and the bridge gets setup but then I lose all connectivity to the router, and cannot reconnect until reboot. Neither the dom0 or domU gets networking in this scenario, I think this has to do with the fact that I am using wpa_supplicant and ndiswrapper for my wireless card and since the bridge technically takes over the connection wpa_supplicant does not have direct access to the card anymore. So due to this, and also the realization that I want the domU and dom0 the have networking even when not connected to an actual network I decided to use a dummy interface as the netdev with dhcp, forwarding dns server, and NAT on this interface,basically making the dom0 a router for the domU. But I cannot get DHCP to start on the dummy interface, I have not tried DNS server yet, and I am unsure of how to set the appropriate iptables rules to NAT from dummy interface to the real active net interface. I do know that setting the IP information manually in the domU does not allow networking between the dummy interface and the domU. So does anyone have any idea how I can get this working? Below is the error I keep recieving for DHCP on the dummy interface.


No subnet declaration for dummy0 (
Aug 28 12:08:01 sleeperdied dhcpd: ** Ignoring requests on dummy0. If this is not what
Aug 28 12:08:01 sleeperdied dhcpd: you want, please write a subnet declaration
Aug 28 12:08:01 sleeperdied dhcpd: in your dhcpd.conf file for the network segment
Aug 28 12:08:01 sleeperdied dhcpd: to which interface dummy0 is attached. **
Aug 28 12:08:01 sleeperdied dhcpd:
Aug 28 12:08:01 sleeperdied dhcpd:
Aug 28 12:08:01 sleeperdied dhcpd: Not configured to listen on any interfaces!

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