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Cannot restore internal snapshots since libvirt 11.2.0
by anonym 12 May '25

12 May '25

Hi! Since libvirt 11.2.0 attempting to restore internal snapshots fails for me with: error: Failed to revert snapshot foo1 error: operation failed: load of internal snapshot 'foo1' job failed: Device 'libvirt-1-format' is writable but does not support snapshots I reported this issue to GitLab [0] where there is more info and a reproducer, but I also wanted to ask the wider community here if anyone has experienced this and maybe even come up with a workaround? [0] https://gitlab.com/libvirt/libvirt/-/issues/771 Cheers!

2 1

vm stopped booting
by daggs 22 Apr '25

22 Apr '25

Greetings, my windows vm stoop working, I think it is related kernel version, 6.14.1 works but 6.14.2 seems not to looking at the libvirt-qemu log file shows this: 2025-04-22 17:28:52.082+0000: starting up libvirt version: 11.2.0, qemu version: 9.2.3, kernel: 6.14.3-gentoo, hostname: NCC-5001D.lan LC_ALL=C \ PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/opt/bin:/usr/lib/llvm/19/bin:/etc/eselect/wine/bin:/opt/cuda/bin \ HOME=/var/lib/libvirt/qemu/domain-1-windows \ USER=root \ XDG_DATA_HOME=/var/lib/libvirt/qemu/domain-1-windows/.local/share \ XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain-1-windows/.cache \ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain-1-windows/.config \ /usr/bin/qemu-system-x86_64 \ -name guest=windows,debug-threads=on \ -S \ -object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain-1-windows/master-key.aes"}' \ -blockdev '{"driver":"file","filename":"/usr/share/edk2/OvmfX64/OVMF_CODE_4M.secboot.qcow2","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \ -blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"qcow2","file":"libvirt-pflash0-storage","backing":null}' \ -blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/windows_VARS.qcow2","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \ -blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"qcow2","file":"libvirt-pflash1-storage","backing":null}' \ -machine pc-q35-8.1,usb=off,smm=on,dump-guest-core=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format,hpet=off,acpi=on \ -accel kvm \ -cpu host,migratable=on,topoext=on,hv-time=on,hv-relaxed=on,hv-vapic=on,hv-spinlocks=0x1fff,hv-vendor-id=wateverr,kvm=off,host-cache-info=on,l3-cache=off \ -global driver=cfi.pflash01,property=secure,value=on \ -m size=31457280k \ -overcommit mem-lock=off \ -smp 16,sockets=1,dies=1,clusters=1,cores=8,threads=2 \ -object '{"qom-type":"memory-backend-memfd","id":"ram-node0","share":true,"size":32212254720}' \ -numa node,nodeid=0,cpus=0-15,memdev=ram-node0 \ -uuid e8fc4f01-5b87-4e2d-a30f-fb72318688f7 \ -display none \ -no-user-config \ -nodefaults \ -chardev socket,id=charmonitor,fd=27,server=on,wait=off \ -mon chardev=charmonitor,id=monitor,mode=control \ -rtc base=localtime,driftfix=slew \ -global kvm-pit.lost_tick_policy=delay \ -no-shutdown \ -global ICH9-LPC.disable_s3=1 \ -global ICH9-LPC.disable_s4=1 \ -boot strict=on \ -device '{"driver":"pcie-root-port","port":16,"chassis":1,"id":"pci.1","bus":"pcie.0","multifunction":true,"addr":"0x2"}' \ -device '{"driver":"pcie-root-port","port":17,"chassis":2,"id":"pci.2","bus":"pcie.0","addr":"0x2.0x1"}' \ -device '{"driver":"pcie-root-port","port":18,"chassis":3,"id":"pci.3","bus":"pcie.0","addr":"0x2.0x2"}' \ -device '{"driver":"pcie-root-port","port":19,"chassis":4,"id":"pci.4","bus":"pcie.0","addr":"0x2.0x3"}' \ -device '{"driver":"pcie-root-port","port":20,"chassis":5,"id":"pci.5","bus":"pcie.0","addr":"0x2.0x4"}' \ -device '{"driver":"pcie-root-port","port":21,"chassis":6,"id":"pci.6","bus":"pcie.0","addr":"0x2.0x5"}' \ -device '{"driver":"pcie-root-port","port":22,"chassis":7,"id":"pci.7","bus":"pcie.0","addr":"0x2.0x6"}' \ -device '{"driver":"pcie-root-port","port":23,"chassis":8,"id":"pci.8","bus":"pcie.0","addr":"0x2.0x7"}' \ -device '{"driver":"pcie-root-port","port":24,"chassis":9,"id":"pci.9","bus":"pcie.0","multifunction":true,"addr":"0x3"}' \ -device '{"driver":"pcie-root-port","port":25,"chassis":10,"id":"pci.10","bus":"pcie.0","addr":"0x3.0x1"}' \ -device '{"driver":"pcie-root-port","port":26,"chassis":11,"id":"pci.11","bus":"pcie.0","addr":"0x3.0x2"}' \ -device '{"driver":"pcie-root-port","port":27,"chassis":12,"id":"pci.12","bus":"pcie.0","addr":"0x3.0x3"}' \ -device '{"driver":"pcie-root-port","port":28,"chassis":13,"id":"pci.13","bus":"pcie.0","addr":"0x3.0x4"}' \ -device '{"driver":"pcie-root-port","port":29,"chassis":14,"id":"pci.14","bus":"pcie.0","addr":"0x3.0x5"}' \ -device '{"driver":"qemu-xhci","p2":15,"p3":15,"id":"usb","bus":"pci.2","addr":"0x0"}' \ -device '{"driver":"virtio-scsi-pci","id":"scsi0","bus":"pcie.0","addr":"0xc"}' \ -blockdev '{"driver":"file","filename":"/usr/share/drivers/windows/virtio-win.iso","node-name":"libvirt-1-storage","read-only":true}' \ -device '{"driver":"ide-cd","bus":"ide.1","drive":"libvirt-1-storage","id":"sata0-0-1"}' \ -chardev socket,id=chr-vu-fs0,path=/var/lib/libvirt/qemu/domain-1-windows/fs0-fs.sock \ -device '{"driver":"vhost-user-fs-pci","id":"fs0","chardev":"chr-vu-fs0","queue-size":1024,"tag":"home@linux","bus":"pci.6","addr":"0x0"}' \ -netdev '{"type":"tap","fd":"29","vhost":true,"vhostfd":"31","id":"hostnet0"}' \ -device '{"driver":"virtio-net-pci","netdev":"hostnet0","id":"net0","mac":"52:54:00:43:79:55","bus":"pci.1","addr":"0x0"}' \ -chardev pty,id=charserial0 \ -device '{"driver":"isa-serial","chardev":"charserial0","id":"serial0","index":0}' \ -chardev socket,id=chrtpm,path=/run/libvirt/qemu/swtpm/1-windows-swtpm.sock \ -tpmdev emulator,id=tpm-tpm0,chardev=chrtpm \ -device '{"driver":"tpm-tis","tpmdev":"tpm-tpm0","id":"tpm0"}' \ -object '{"qom-type":"input-linux","id":"input0","evdev":"/var/lib/libvirt/helpers_state/windows/mouse-event"}' \ -object '{"qom-type":"input-linux","id":"input1","evdev":"/var/lib/libvirt/helpers_state/windows/keyboard-event","repeat":true,"grab_all":true,"grab-toggle":"ctrl-ctrl"}' \ -audiodev '{"id":"audio1","driver":"none"}' \ -global ICH9-LPC.noreboot=off \ -watchdog-action reset \ -device '{"driver":"vfio-pci","host":"0000:06:00.0","id":"hostdev0","bus":"pci.5","multifunction":true,"addr":"0x0","romfile":"/var/lib/libvirt/roms/gpu-10de:1c82-uefi.rom"}' \ -device '{"driver":"vfio-pci","host":"0000:06:00.1","id":"hostdev1","bus":"pci.5","addr":"0x0.0x1"}' \ -device '{"driver":"vfio-pci","host":"0000:04:00.1","id":"hostdev2","bus":"pci.7","addr":"0x0"}' \ -device '{"driver":"vfio-pci","host":"0000:08:00.4","id":"hostdev3","bus":"pci.4","addr":"0x0"}' \ -device '{"driver":"vfio-pci","host":"0000:03:00.0","id":"hostdev4","bus":"pci.9","addr":"0x0"}' \ -device '{"driver":"usb-host","hostdevice":"/dev/bus/usb/003/002","id":"hostdev5","bus":"usb.0","port":"1"}' \ -device '{"driver":"usb-host","id":"hostdev6","bus":"usb.0","port":"2"}' \ -device '{"driver":"usb-host","hostdevice":"/dev/bus/usb/001/002","id":"hostdev7","bus":"usb.0","port":"3"}' \ -device '{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.3","addr":"0x0"}' \ -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ -msg timestamp=on 2025-04-22 17:28:52.084+0000: 5390: debug : virProcessSetMaxMemLock:923 : Locked memory for process 5390 limited to 33285996544 bytes 2025-04-22 17:28:52.084+0000: 5390: debug : virExec:881 : Run hook 0x7fb3b82902a0 0x7fb3bb4435d0 2025-04-22 17:28:52.084+0000: 5390: debug : qemuProcessHook:3136 : Obtaining domain lock 2025-04-22 17:28:52.084+0000: 5390: debug : virDomainLockProcessStart:175 : plugin=0x7fb37016de00 dom=0x7fb3704b9bd0 paused=1 fd=0x7fb3bb4432f0 2025-04-22 17:28:52.084+0000: 5390: debug : virDomainLockManagerNew:130 : plugin=0x7fb37016de00 dom=0x7fb3704b9bd0 withResources=1 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerPluginGetDriver:275 : plugin=0x7fb37016de00 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerNew:298 : driver=0x7fb3c09e5440 type=0 nparams=5 params=0x7fb3bb4431d0 flags=0x1 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerLogParams:96 : key=uuid type=uuid value=e8fc4f01-5b87-4e2d-a30f-fb72318688f7 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerLogParams:89 : key=name type=string value=windows 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerLogParams:77 : key=id type=uint value=1 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerLogParams:77 : key=pid type=uint value=5390 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerLogParams:92 : key=uri type=cstring value=qemu:///system 2025-04-22 17:28:52.084+0000: 5390: debug : virDomainLockManagerNew:143 : Adding leases 2025-04-22 17:28:52.084+0000: 5390: debug : virDomainLockManagerNew:148 : Adding disks 2025-04-22 17:28:52.084+0000: 5390: debug : virDomainLockManagerAddImage:87 : Add disk /usr/share/drivers/windows/virtio-win.iso 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerAddResource:324 : lock=0x7fb3b0044350 type=0 name=/usr/share/drivers/windows/virtio-win.iso nparams=0 params=(nil) flags=0x1 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerAcquire:342 : lock=0x7fb3b0044350 state='<null>' flags=0x3 action=0 fd=0x7fb3bb4432f0 2025-04-22 17:28:52.084+0000: 5390: debug : virLockManagerFree:380 : lock=0x7fb3b0044350 2025-04-22 17:28:52.084+0000: 5390: info : virObjectUnref:378 : OBJECT_UNREF: obj=0x7fb370114eb0 2025-04-22 17:28:52.084+0000: 5390: debug : qemuProcessHook:3181 : Hook complete ret=0 2025-04-22 17:28:52.084+0000: 5390: debug : virExec:883 : Done hook 0 2025-04-22 17:28:52.084+0000: 5390: debug : virExecCommon:456 : Setting child uid:gid to 77:77 with caps 0 2025-04-22 17:28:52.084+0000: 5390: debug : virCommandHandshakeChild:402 : Notifying parent for handshake start on 33 2025-04-22 17:28:52.084+0000: 5390: debug : virCommandHandshakeChild:410 : Waiting on parent for handshake complete on 34 2025-04-22 17:28:52.100+0000: 5390: error : virCommandHandshakeChild:418 : libvirtd quit during handshake: Input/output error libvirt: error : libvirtd quit during handshake: Input/output error 2025-04-22 17:28:52.100+0000: shutting down, reason=failed any hints on what can cause the handshake error?

1 0

virt-manager with SSH and 2FA with TOTP?
by Andreas Haumer 15 Apr '25

15 Apr '25

Hi! (I hope, this is the right list for my question. I already posted it to the debian-user ML, but someone pointed me to this list. Alas, there is no virt-manager ML anymore) In our network we have several Debian systems working as VM host running QEMU+KVM based virtual machines. I usually use virt-manager on my workstation as GUI to connect to the VM host, manage the VMs and also to connect to the VM console if needed. To connect to the VM host I use SSH with public key authentication. On the commandline with virsh this looks like this (example): andreas@ws1:~> virsh -c qemu+ssh://root@maxwell/system Welcome to virsh, the virtualization interactive terminal. Type: 'help' for help with commands 'quit' to quit virsh # So far, so good. Recently I decided to increase our internal network security standards and activated 2FA with time-based one-time passwords on several hosts. (The idea is to eventually have 2FA for SSH for all users on all hosts in our network) This works very well and even quite comfortable with authenticator-apps on my smartphone or KeePassXC on my workstation generating the TOTP. Example: andreas@ws1:~> ssh root@mach Enter OTP: Linux mach 6.1.0-32-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.129-1 (2025-03-06) x86_64 root@mach:~# So for a successful SSH connection I now have to enter a valid TOTP (generated by the authenticator app) and then it connects. Connecting to the host with virsh on the commandline also works in a similar way: andreas@ws1:~> virsh -c qemu+ssh://root@mach/system Enter OTP: Welcome to virsh, the virtualization interactive terminal. Type: 'help' for help with commands 'quit' to quit virsh # All fine. Works as designed... When I use virt-manager to connect to the VM host, the GUI opens a dialog asking for the OTP and then connects, showing the list of all configured VMs etc. I can also open the configuration of a given VM, manage and change it. All fine, too... But when I try to use virt-manager to connect to the console of a specific VM, it doesn't work as expected. virt-manager opens a new window for the console, but also endlessly keeps opening password entry dialogs. As soon as I enter the current OTP and klick "ok", another dialog is opened, again asking for another OTP. And so on... (These are one-time passwords, valid for 30 seconds, which cannot be re-used) I can connect to the VM console with a SPICE viewer like remmina using SSH port forwarding like this: andreas@ws1:~> ssh -L 5906:localhost:5906 root@mach Enter OTP: root@mach:~# (where 5906 is the SPICE port for the VM in question) And then use remmina to connect to port 5906 on localhost. This gives me the SPICE console of the VM. Of course, this is not as comfortable as using virt-manager. But with virt-manager I haven't found a way to successfully connect to the VM console with 2FA in place. So, finally, my question: Did anyone on this list manage to use virt-manager to connect to a VM console using SSH with 2FA? Thanks! - andreas -- Andreas Haumer *x Software + Systeme | mailto:andreas@xss.co.at Karmarschgasse 51/2/20 | https://www.xss.co.at/ A-1100 Vienna, Austria | Tel: +43-1-6060114

5 8

Is there any way to apply firewall rules to passt user mode networking?
by notsyncing＠163.com 12 Apr '25

12 Apr '25

Hello, I'm testing user mode network under session mode with libvirt and passt backend, and I found that the guest vm can access the whole host LAN(host is 192.168.1.2, guest ip configured to 192.168.100.2, but guest can access 192.168.1.3, which should not be allowed). Using firewalld dropping all traffic from guest ip has no effect at all. Is there any way to prevent guest accessing host LAN, while keeping guest's internet access? Thanks!

1 0

iptables rule affects vnet0?
by daggs 09 Apr '25

09 Apr '25

Greetings, I have a 2 vms on a host that can communicate with other hosts on the system. the two vms are connected by a virtsw0 bridge (vm1 and vm2) and on of the vms (vm1) has another connection (vnet0) to the host. it seems that the host can only communicate with the vm that has a direct connection to it and not the other vm (virtsw0 allows connection beteen both vms) here are the rules libvirt creates: -P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT -N LIBVIRT_FWI -N LIBVIRT_FWO -N LIBVIRT_FWX -N LIBVIRT_INP -N LIBVIRT_OUT -A INPUT -j LIBVIRT_INP -A FORWARD -j LIBVIRT_FWX -A FORWARD -j LIBVIRT_FWI -A FORWARD -j LIBVIRT_FWO -A OUTPUT -j LIBVIRT_OUT -A LIBVIRT_FWI -o virsw0 -j REJECT --reject-with icmp-port-unreachable -A LIBVIRT_FWO -i virsw0 -j REJECT --reject-with icmp-port-unreachable -A LIBVIRT_FWX -i virsw0 -o virsw0 -j ACCEPT -A LIBVIRT_INP -i virsw0 -p udp -m udp --dport 53 -j ACCEPT -A LIBVIRT_INP -i virsw0 -p tcp -m tcp --dport 53 -j ACCEPT -A LIBVIRT_INP -i virsw0 -p udp -m udp --dport 67 -j ACCEPT -A LIBVIRT_INP -i virsw0 -p tcp -m tcp --dport 67 -j ACCEPT -A LIBVIRT_OUT -o virsw0 -p udp -m udp --dport 53 -j ACCEPT -A LIBVIRT_OUT -o virsw0 -p tcp -m tcp --dport 53 -j ACCEPT -A LIBVIRT_OUT -o virsw0 -p udp -m udp --dport 68 -j ACCEPT -A LIBVIRT_OUT -o virsw0 -p tcp -m tcp --dport 68 -j ACCEPT and here are the stats: Chain INPUT (policy ACCEPT 17405 packets, 1677K bytes) pkts bytes target prot opt in out source destination 17434 1688K LIBVIRT_INP all -- * * 0.0.0.0/0 0.0.0.0/0 Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 LIBVIRT_FWX all -- * * 0.0.0.0/0 0.0.0.0/0 0 0 LIBVIRT_FWI all -- * * 0.0.0.0/0 0.0.0.0/0 0 0 LIBVIRT_FWO all -- * * 0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (policy ACCEPT 21058 packets, 3788K bytes) pkts bytes target prot opt in out source destination 21058 3788K LIBVIRT_OUT all -- * * 0.0.0.0/0 0.0.0.0/0 Chain LIBVIRT_FWI (1 references) pkts bytes target prot opt in out source destination 0 0 REJECT all -- * virsw0 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable Chain LIBVIRT_FWO (1 references) pkts bytes target prot opt in out source destination 0 0 REJECT all -- virsw0 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable Chain LIBVIRT_FWX (1 references) pkts bytes target prot opt in out source destination 0 0 ACCEPT all -- virsw0 virsw0 0.0.0.0/0 0.0.0.0/0 Chain LIBVIRT_INP (1 references) pkts bytes target prot opt in out source destination 0 0 ACCEPT udp -- virsw0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53 0 0 ACCEPT tcp -- virsw0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 29 10608 ACCEPT udp -- virsw0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67 0 0 ACCEPT tcp -- virsw0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67 Chain LIBVIRT_OUT (1 references) pkts bytes target prot opt in out source destination 0 0 ACCEPT udp -- * virsw0 0.0.0.0/0 0.0.0.0/0 udp dpt:53 0 0 ACCEPT tcp -- * virsw0 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 0 0 ACCEPT udp -- * virsw0 0.0.0.0/0 0.0.0.0/0 udp dpt:68 0 0 ACCEPT tcp -- * virsw0 0.0.0.0/0 0.0.0.0/0 tcp dpt:68 is it possible I cannot access vm2 from the host because of the rules above? Thanks, Dagg

1 0

How to use microVM as a machine type?
by Qu Wenruo 08 Apr '25

08 Apr '25

Hi, Recently I'm hitting a bug related to edk2 that sometimes boot up can be very slow (before loading the bootloader): https://github.com/tianocore/edk2/issues/10765 It looks like the cause is the related to flash IOs. So I want to try using microVM machine type, as it's json file describes the device mapping is "memory", which should work around the slow boot. But I'm unable to setup a machine using microVM machine type in virtual-manager. And manually editing the xml file doesn't let me go any further, as VMM creates a default xml with ACPI feature, which is not supported by microVM. So I'm wondering, what's the proper way to use microVM machine type inside libvirt? Thanks, Qu

2 1

libvirt KVM virtual NIC as ens160 for running a virtual appliance designed for Vmware
by Sascha Frey 31 Mar '25

31 Mar '25

Hi, I want to run a virtual appliance which was designed for Vmware on libvirt Linux/KVM. Unfortunately, they hardcoded the kernel NIC name to ens160 inside that image. I can create a libvirt XML which creates a NIC recognised as ensXX, but not ens160, because libvirt doesn’t allow PCI slots over 0x1f. Is there any possible way to create a virtual NIC ens160 without modifying the image? Thanks.

2 1

Re: Capture pcap for each VM
by Laine Stump 31 Mar '25

31 Mar '25

(added users(a)lists.libvirt.org back into the Cc so that anyone else asking the same question in the future will benefit from the answer) On 3/28/25 8:12 AM, James Liu wrote: > Hi Laine, > > I tried your first solution but somehow it didn't work(the network is > NAT). I edited the xml in virt-manager gui. Whenever I added following > options, and click "Apply", the virt-manager will revert(remove) the > "alias" tag; consequently, the qemu command line couldn't find the > device name('foo' in this example). Sorry, I had meant to point this out but somehow forgot - user-specified aliases must begin with "ua-", otherwise they will be ignored. So instead of using "<alias name='foo'/>", use "<alias name='ua-foo'/>" (and then in the <qemu:arg value> use "netdev=hostua-foo") Also note that your guest should be shutdown while you're making these changes. > > Appreciate your suggestions. > > <interface type="network"> > <mac address="52:54:00:3a:bf:52"/> > <source network="default"/> > <model type="e1000e"/> > <alias name="*foo*"/> # virt-manager will always remove > this tag > <address type="pci" domain="0x0000" bus="0x01" slot="0x00" > function="0x0"/> > </interface> > > <qemu:commandline> > <qemu:arg value="-object"/> > <qemu:arg value="filter-dump,id=f1,netdev=*foo*,file=/tmp/xyzzy.pcap"/> > </qemu:commandline>

1 0

Clarifying isolated network rules in nftables
by Alexey Kashavkin 27 Mar '25

27 Mar '25

Hi, I’m trying to understand how firewall filter works for isolated network in libvirt v11.1.0. When I start the network I can see following rules in nftables: table ip libvirt_network { chain forward { type filter hook forward priority filter; policy accept; counter packets 0 bytes 0 jump guest_cross counter packets 0 bytes 0 jump guest_input counter packets 0 bytes 0 jump guest_output } chain guest_output { iif "virbr3" counter packets 0 bytes 0 reject } chain guest_input { oif "virbr3" counter packets 0 bytes 0 reject } chain guest_cross { iif "virbr3" oif "virbr3" counter packets 0 bytes 0 accept } chain guest_nat { type nat hook postrouting priority srcnat; policy accept; } } But when I start ping from one VM to another on the same isolated network, I don't see an increase in counters in either chain. In the libvirt code, I found a comment in src/network/network_nftables.c: /** * nftablesAddForwardAllowCross: * * Add a rule to @fw to allow traffic to go across @iface (the virtual * network's bridge) from one port to another. This allows all traffic * between guests on the same virtual network. */ But it seems that these rules don't work and are not needed. If I delete this table or some chains, nothing happens. VMs have connectivity with each other on this network. What are these rules for?

2 1

Capture pcap for each VM
by icefrog1950＠gmail.com 26 Mar '25

26 Mar '25

Hi, Is possible to capture pcaps for each VM individually? QEMU supports command line '-object filter-dump, file=test.pcap'. I'm not sure if Libvirt supports this features, or there are better ways to solve this. Many thanks.

2 1