Bug 807879

Summary: When running inside a KVM, libvirt sets up a virbr0 with IP of (same as virbr0 on the host), screwing up the KVM's networking
Product: [Fedora] Fedora Reporter: Adam Williamson <awilliam>
Component: libvirtAssignee: Libvirt Maintainers <libvirt-maint>
Status: CLOSED DUPLICATE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 17CC: berrange, clalancette, crobinso, dougsland, itamar, jforbes, jhrozek, jyang, laine, libvirt-maint, notting, robatino, rstrode, veillard, virt-maint
Target Milestone: ---   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2012-03-29 00:37:26 EDT Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On:    
Bug Blocks: 752649    

Description Adam Williamson 2012-03-28 22:24:44 EDT
I'm no networking expert, so there may be errors in the description here, but I hope the gist comes through.

If you just use Fedora's default virt stack to set up a VM, in the dumb pointy-clicky virt-manager way, you'll get a 'virbr0' interface on the host machine with an IP of VMs will have 'eth0' interfaces with IP address in the 192.168.122.[2-255] range (actually probably a narrower higher range, but you get the idea). Effectively libvirt is handling NAT for the VMs behind it. The VMs get their DNS server set to, and everything works, and I don't have to think too hard about why.

If I boot a VM using a live image which has Boxes included (and probably if you just 'yum install boxes' into a VM and reboot), the *VM itself* has a virbr0 interface with an IP of The VM can ping out to numeric IP addresses, it seems - ping works - but it can't resolve any hostnames, presumably because the guest virbr0 is conflicting with the host virbr0 and messing things up.

I have no idea how this should be fixed, I just know it should, because the user-visible impact is that 'networking is horked in KVMs with Boxes installed'.

This may be a libvirt issue rather than a Boxes one, I guess. I'm not sure. CCing the Dans Berrange and Veillard.

If we wanted to have Boxes in the F17 release, this would be a release blocker.
Comment 1 Adam Williamson 2012-03-28 22:27:54 EDT
wrong Boxes. let's just assign this to libvirt, anyhow.

Fedora Bugzappers volunteer triage team
Comment 2 Adam Williamson 2012-03-29 00:05:00 EDT
Well, fuck.

Bill added gnome-boxes to comps a day or so ago:


so this is now affecting Beta RC2 :(

Network is broken OOTB with Beta RC2 Desktop booted in a KVM. Proposing as Beta blocker.

Fedora Bugzappers volunteer triage team
Comment 3 Adam Williamson 2012-03-29 00:37:26 EDT

Fedora Bugzappers volunteer triage team

*** This bug has been marked as a duplicate of bug 802475 ***