On 11/28/2011 12:07 PM, Patrick Lists wrote: > Hi, > > I have a workstation with Fedora 16 using NetworkManager getting a > static IP address via DHCP from a central DHCP server. I have a couple > of VMs on that workstation that use a routed network device in libvirt > that I would also like to acquire their IP address from the central DHCP > server. > > I set up the virtual routed network device virbr1 and configured a VM > (with CentOS 6) to use it. When the VM starts I see in Wireshark the > DHCP broadcasts on the virbr1 interface but those broadcasts are not > seen on the p21p1 (the old eth0) interface on the workstation and > definitely don't make it to the central DHCP server. I guess I may need > some additional IPTables rules to forward the VMs DHCP requests to the > central DHCP server? Does anyone know what IPTables rule(s) I should add > to make this work? > My understanding and experience is that you really want to bridge the virtual machines to get them on the real network. It can get very interesting when you add VLANs per virtual machine, or groups of virtual machines. NetworkManager can handle bridges ok, and I do so on my desktop, but on all of our VM servers we shut of/don't install NetworkManager and just use network. The principles are the same which ever you wish to use. # yum -y install bridge-utils This is a blip from our kickstart post-install for desktops and 'livecd' based VM servers: # set up a bridge on eht0 cat > /etc/sysconfig/network-scripts/ifcfg-br0 <<_EOF DEVICE=br0 ONBOOT=yes TYPE=Bridge BOOTPROTO=dhcp STP=off DELAY=0 NM_CONTROLLED="yes" _EOF cat > /etc/sysconfig/network-scripts/ifcfg-eth0 <<_EOF DEVICE=eth0 ONBOOT=yes BRIDGE=br0 NM_CONTROLLED="yes" _EOF This gives you the bridge, and all the virt tools will see it. You would use p21p1, of course, or force udev to give you the old names. Now that you have the bridge, you can specify it in the installs of your VMs. They can do dhcp on the same network the server does. This can be extended without much fuss to include VLANs as well. Here is a sample from a startup script for a livecd based VM server that requires a different VLAN for one of the two VMs he serves: modprobe 8021q vconfig add eth1 840 vconfig add eth1 60 ifconfig inet 0.0.0.0 eth1.60 cat > /etc/sysconfig/network-scripts/ifcfg-br1 <<_EOF DEVICE=br1 ONBOOT=yes TYPE=Bridge BOOTPROTO=none STP=off DELAY=0 _EOF cat > /etc/sysconfig/network-scripts/ifcfg-eth1.60 <<_EOF DEVICE=eth1.60 ONBOOT=yes VLAN=yes BRIDGE=br1 _EOF cat > /etc/sysconfig/network-scripts/ifcfg-eth1.840 <<_EOF DEVICE=eth1.840 ONBOOT=yes VLAN=yes IPADDR=10.150.0.102 NETMASK=255.255.252.0 _EOF ifup eth1.840 ifup eth1.60 ifup br1 It is my experience that when using tagged VLANs such as this, that the bridge cannot successfully do dhcp because the underlying VLAN does not come up until after the bridge in this case. Other than that one CAVEAT, this works well. Need a VM on VLAN 60? Just define his interface on bridge br1. No need to do any bridging or VLAN setup inside the VM. Bridges are the bomb. Use 'em. Good luck! -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
