[CentOS] Connecting ethX devices directly to a KVM/QEMU guest OS (no bridging)

Wed Jan 18 19:45:45 UTC 2012
Chuck Munro <chuckm at seafoam.net>

Hello CentOS gurus, and a belated Happy New Year (or an early Happy 
Chinese New Year).

I'm in the process of building a CentOS-6 KVM host machine whose only 
function will be to run four independent 'm0n0wall' firewall guest 
instances. I have a couple of quad-port Intel NICs to provide four 
WAN-side and four LAN-side ports, which will not be shared with any 
other guests. Remote access to the host CentOS is via a separate 
on-board NIC, so the Intel ports are free to assign.

I've Googled until I'm blue in the face, but haven't found a clear 
explanation of how I can assign each ethX device directly to the guest 
OS rather than going thru the usual bridge configuration. I need to 
allow the m0n0wall OS to assign the LAN and WAN IP addresses, if that's 
possible without using a bridge.

Using the Virtual Machine Manager GUI to create the VM guests (which 
boot up and run nicely), the drop-down list shows all of the ethX 
devices greyed out. Do I need to somehow start the NICs without 
assigning IP addresses, so that they show up in 'ifconfig'?

Can anyone provide a clear, easy-to-understand procedure for doing this? 
If necessary, I don't mind using the command-line to create the VMs but 
the docs aren’t totally clear (to me, at least) regarding NIC assignment.

Thanking you in advance for your suggestions,
Chuck