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Description of problem:
When adding a directly attached interface (interface type == direct attachment), the newly created interface is configured in vepa mode (libvirt default). Considering how rare are vepa-capable switches, this means that guests with directly attached interfaces can not talk each others. This choice basically makes directly attached interfaces created via cockpit-machines useless.
For this reason, virt-manager automatically creates bridge mode direct attached interfaces when selecting macvtap networking. Bridge mode enables guests to talk each other, while ensuring the added security guarantees regarding guest to host networking (which is prevented by design).
While "pure" bridge networking (ie: interface type == bridge to lan) is available, it has two significant drawbacks compared to bridge-mode directly attached interfaces: a) it is slower and b) it does not prevent guest to host communication by design.
Please consider changing the default for "interface type == direct attachment" to create bridge-mode macvtap interfaces. Or, at the very least, please add an option to select the interface mode (defaulting to bridge would be recommended).
Version-Release number of selected component (if applicable):
cockpit-machines-263-1.el9.noarch.rpm
How reproducible:
Always
Steps to Reproduce:
1. add a directly attached interface via cockpit to two guests
2. let a guest ping the other one
3. all packet are lost
Actual results:
No communication between guest is possible
Expected results:
Guest-to-guest communication should work out-of-the-box.
Additional info:
None.
Test Versions:
cockpit-290-1.el9.x86_64
cockpit-machines-288-1.el9.noarch
libvirt-dbus-1.4.1-5.el9.x86_64
Test Steps:
1 Create two closed VM
2 Remove the default network interfaces, and attach "Direct attachment" network interface for the VMs
3 Check the VM XMLs
4 In one of the VM, ping the other VM
Test Results:
1 After step 3, the interface source mode should be "bridge" for the VMs
2 After step 4, ping should be successful
According to the results, move status to VERIFIED.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (cockpit-machines bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2023:6336