Bug 1432756 - [libvirt] networking broken in Fedora 25 guest on Fedora 26 host
Summary: [libvirt] networking broken in Fedora 25 guest on Fedora 26 host
Keywords:
Status: CLOSED DUPLICATE of bug 1146232
Alias: None
Product: Fedora
Classification: Fedora
Component: libvirt
Version: 26
Hardware: x86_64
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Libvirt Maintainers
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-03-16 06:40 UTC by Joachim Frieben
Modified: 2017-03-16 18:14 UTC (History)
9 users (show)

Fixed In Version:
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Clone Of:
Environment:
Last Closed: 2017-03-16 18:14:17 UTC
Type: Bug
Embargoed:


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Description Joachim Frieben 2017-03-16 06:40:01 UTC
Description of problem:
After installing a virtual Fedora 25 guest on a Fedora 26 host, networking is broken in the virtual guest because of conflicting interfaces ens3 and virbr0. Thus, ifconfig reports:

$ ifconfig 
ens3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.124.228  netmask 255.255.255.0  broadcast 192.168.124.255
        inet6 fe80::9d60:424d:6e3f:1028  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:da:5a:22  txqueuelen 1000  (Ethernet)
        RX packets 9  bytes 1117 (1.0 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 38  bytes 5411 (5.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 72

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 96  bytes 6400 (6.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 96  bytes 6400 (6.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 192.168.124.1  netmask 255.255.255.0  broadcast 192.168.124.255
        ether 52:54:00:11:fe:b0  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

When the host system is using Fedora 25, then the inet of interface ens3 is 192.168.122.x which does not conflict with the inet 192.168.124.x of interface vibr0.

Version-Release number of selected component (if applicable):
libvirt-3.1.0-1.fc26.

How reproducible:
Always (when certain conditions are met).

Steps to Reproduce:
1. Install Fedora 25 in a virtual guest.
2. Reboot system.

Actual results:
The wired-connection icon exhibits a question mark, and name resolution is broken.

Expected results:
The wired-connection is working correctly including name resolution.

Additional info:
This issue is complex because is depends on the systes which are installed on the host and on the guest, respectively: 
1. When the host system is using Fedora 25, too, no conflict occurs.
2. When the relevant virtualization-related packages are removed from the guest, then no conflict occurs, because interface virbr0 is absent right from the start. Therefore, no problem is ever observed e.g. after installing CentOS 7.x on the guest. Uninstalling libvirt packages is the safest manner to restore proper networking for the virtual guest.
3. When booting Fedora 25 live media (official or updated) on the guest system, no interface virbr0 is present at all, and thus no conflict occurs either. Interface virbr0 only appears after booting up the installed system, sometimes even only after additionally updating the kernel package.

Comment 1 Cole Robinson 2017-03-16 18:14:17 UTC

*** This bug has been marked as a duplicate of bug 1146232 ***


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