Greetings Laine, > Sent: Tuesday, May 01, 2018 at 5:30 PM > From: "Laine Stump" <laine@xxxxxxxxxx> > To: libvirt-users@xxxxxxxxxx > Cc: daggs <daggs@xxxxxxx> > Subject: Re: connecting host and guest vm using a dummy nic > > On 04/30/2018 03:16 PM, daggs wrote: > > Greetings Laine, > > > >> Sent: Monday, April 30, 2018 at 8:31 PM > >> From: "Laine Stump" <laine@xxxxxxxxxx> > >> To: libvirt-users@xxxxxxxxxx > >> Cc: daggs <daggs@xxxxxxx> > >> Subject: Re: connecting host and guest vm using a dummy nic > >> > >> On 04/27/2018 06:39 PM, daggs wrote: > >>> Greetings all, > >>> > >>> I have a host machine that runs a router within a vm. > >>> I want to allow a connection between the host and the guest so the host can connect to the lan provided by the router vm. > >>> I've created a dummy interface with these commands: > >>> $ ip link add ens99-dummy type dummy > >>> $ ip link set ens99-dummy address 52:54:00:1f:d0:ff > >>> > >>> this resulted with this output: > >>> $ ifconfig ens99-dummy > >>> ens99-dummy Link encap:Ethernet HWaddr 52:54:00:1F:D0:FF > >>> inet6 addr: fe80::84b5:24ff:fe62:c16d/64 Scope:Link > >>> UP BROADCAST RUNNING NOARP MTU:1500 Metric:1 > >>> RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > >>> TX packets:899 errors:0 dropped:0 overruns:0 carrier:0 > >>> collisions:0 txqueuelen:1000 > >>> RX bytes:0 (0.0 B) TX bytes:321727 (314.1 KiB) > >>> > >>> > >>> in my libvirt's xml file I have this entry: > >>> <interface type='direct'> > >>> <mac address='52:54:00:0c:cb:3e'/> > >>> <source dev='ens99-dummy' mode='private'/> > >>> <target dev='macvtap0'/> > >>> <model type='e1000'/> > >>> <alias name='net0'/> > >>> <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/> > >>> </interface> > >> > >> MY first question would be "Why are you using macvtap?" This > >> unnecessarily complicates the plumbing, leading to more potential places > >> where it could fail. > > misconfiguration, question is, what should be the exact config for this. > > > >> > >> The 2nd question is - Have you looked at the dhcp server running on the > >> guest to verify that it is indeed listening for DHCP requests on the > >> guest-side interface associated with the macvtap interface, and that it > >> is receiving those requests and sending a reply? > > will test it. as said before, I'm not sure what should be the proper config in libvirt. > > > >> > >>> > >>> after the vm is up, I see the adapter in the vm and the host has one more entry: > >>> $ ifconfig macvtap0 > >>> macvtap0 Link encap:Ethernet HWaddr 52:54:00:0C:CB:3E > >>> inet6 addr: fe80::5054:ff:fe0c:cb3e/64 Scope:Link > >>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > >>> RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > >>> TX packets:889 errors:0 dropped:0 overruns:0 carrier:0 > >>> collisions:0 txqueuelen:500 > >>> RX bytes:0 (0.0 B) TX bytes:320523 (313.0 KiB) > >>> > >>> but when I try to request ip via dhcp from both macvtap0 and ens99-dummy I don't get any. > >>> any idea why? > >> > >> Definitely you wouldn't be able to use the macvtap0 device, so if > >> anything you would want to be using ens99-dummy, but I'm not even > >> certain *that* would work, as I've never tried it. > > so use ens99-dummy directly? > > My suggestion is to scrap the idea of using macvtap and a dummy link > entirely, and just use a plain tap device. I can't think of any reason > why you would want to use macvtap rather than tap in this case > > > > >> > >> You've provided no visibility into the configuration of the guest OS in > >> your virtual machine, but in general if you want a simple connection > >> between the host and guest that has *no other connections*, you can do > >> this with a bare tap device: > > like this: > > >> > >> <interface type='ethernet'> > >> <model type='e1000'/> > >> </interface> > >> > >> This will show up as a single device on the host and a single device in > >> the guest, not connected to a bridge or a macvtap device or anything, > >> and will not need any other "ip link blah blah" type setup on the host. > >> Simplifying your setup in this manner may make it easier to find the > >> source of your problem. > >> > > > > ok, here is the entire xml file: > > (I actually meant the network configuration within the guest OS, not the > libvirt config of the virtual machine it's running on) > > > > > > <domain type='kvm'> > > <name>router</name> > > <uuid>ed8eabe2-ced3-4224-aa12-60fb31dd3fd4</uuid> > > <memory unit='KiB'>1048576</memory> > > <currentMemory unit='KiB'>1048576</currentMemory> > > <vcpu placement='static'>2</vcpu> > > <os> > > <type arch='x86_64' machine='pc-q35-2.8'>hvm</type> > > <boot dev='hd'/> > > </os> > > <features> > > <acpi/> > > <apic/> > > </features> > > <cpu mode='host-passthrough'/> > > <clock offset='utc'> > > <timer name='rtc' tickpolicy='catchup'/> > > <timer name='pit' tickpolicy='delay'/> > > <timer name='hpet' present='no'/> > > </clock> > > <on_poweroff>destroy</on_poweroff> > > <on_reboot>restart</on_reboot> > > <on_crash>restart</on_crash> > > <pm> > > <suspend-to-mem enabled='no'/> > > <suspend-to-disk enabled='no'/> > > </pm> > > <devices> > > <emulator>/usr/bin/kvm</emulator> > > <disk type='file' device='disk'> > > <driver name='qemu' type='raw'/> > > <source file='/home/router/lede-x86-64-combined-ext4.img'/> > > <target dev='vda' bus='virtio'/> > > <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/> > > </disk> > > <controller type='usb' index='0' model='ich9-ehci1'> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/> > > </controller> > > <controller type='usb' index='0' model='ich9-uhci1'> > > <master startport='0'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/> > > </controller> > > <controller type='usb' index='0' model='ich9-uhci2'> > > <master startport='2'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/> > > </controller> > > <controller type='usb' index='0' model='ich9-uhci3'> > > <master startport='4'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/> > > </controller> > > <controller type='sata' index='0'> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/> > > </controller> > > <controller type='pci' index='0' model='pcie-root'/> > > <controller type='pci' index='1' model='dmi-to-pci-bridge'> > > <model name='i82801b11-bridge'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/> > > </controller> > > <controller type='pci' index='2' model='pci-bridge'> > > <model name='pci-bridge'/> > > <target chassisNr='2'/> > > <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/> > > </controller> > > <controller type='pci' index='3' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='3' port='0x8'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/> > > </controller> > > <controller type='pci' index='4' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='4' port='0x9'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> > > </controller> > > <controller type='pci' index='5' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='5' port='0xa'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> > > </controller> > > <controller type='pci' index='6' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='6' port='0xb'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x3'/> > > </controller> > > <controller type='pci' index='7' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='7' port='0xc'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x4'/> > > </controller> > > <controller type='pci' index='8' model='pcie-root-port'> > > <model name='ioh3420'/> > > <target chassis='8' port='0xd'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x5'/> > > </controller> > > <interface type='direct'> > > <mac address='52:54:00:e7:90:bc'/> > > <source dev='ens99-dummy' mode='vepa'/> > > <model type='rtl8139'/> > > <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/> > > </interface> > > <serial type='pty'> > > <target type='isa-serial' port='0'/> > > </serial> > > <console type='pty'> > > <target type='serial' port='0'/> > > </console> > > <input type='mouse' bus='ps2'/> > > <input type='keyboard' bus='ps2'/> > > <hostdev mode='subsystem' type='usb' managed='yes'> > > <source> > > <vendor id='0x148f'/> > > <product id='0x5572'/> > > </source> > > <address type='usb' bus='0' port='1'/> > > </hostdev> > > <hostdev mode='subsystem' type='pci' managed='yes'> > > <source> > > <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/> > > </source> > > <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/> > > </hostdev> > > <hostdev mode='subsystem' type='pci' managed='yes'> > > <source> > > <address domain='0x0000' bus='0x03' slot='0x00' function='0x0'/> > > </source> > > <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> > > </hostdev> > > <hostdev mode='subsystem' type='pci' managed='yes'> > > <source> > > <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/> > > </source> > > <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> > > </hostdev> > > <memballoon model='virtio'> > > <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/> > > </memballoon> > > </devices> > > </domain> > > > > what I don't get is how to connect the interface above to the dummy one I've created. > > > > That's easy. Don't - see my suggestion above about using a tap device > instead of the macvtap+dummy combination (actually, I had thought the > "<source dev='ens99-dummy' ..." should connect the two, but according to > your experiments that doesn't result in a working setup, so...) > I want to see if I understood you correctly, I add: <interface type='ethernet'> <model type='e1000'/> </interface> to the vm's xml, this will result in a new nic in the vm which and in the host which I can use by the host to request dhcp from the router within the vm? Thanks, Dagg. _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
