QEMU with KVM: Can not ping or SSH between host and guest machines

Edit: Since macvtap is not working for communication between host and guest, I tried to used a bridge, but then there's no internet on the host and ping or ssh still doesn't work.

This is how I've created a bridge:

nmcli connection add type bridge ifname br0Output:Connection 'bridge-br0' (bf1406b0-4ea8-4338-9edc-0f58fd019bec) successfully added.nmcli con add type ethernet con-name br-slave-1 ifname enp0s25 master br0nmcli con add type ethernet con-name br-slave-1 ifname enp0s25 master br0nmcli con modify bridge-br0 bridge.stp nonmcli connection add type ethernet ifname  bridge-br0  ipv4.method autoOutput:Connection 'ethernet-bridge-br0' (6c2c5495-6e43-4cd5-a574-014042987781) successfully added.After reboot:nmcli con showNAME                       UUID                                  TYPE      DEVICE  bridge-br0                 bf1406b0-4ea8-4338-9edc-0f58fd019bec  bridge    br0     br-slave-1                 a998c09f-5f46-4586-b654-cdfa6a21dca5  ethernet  enp0s25 ethernet-bridge-br0        6c2c5495-6e43-4cd5-a574-014042987781  ethernet  --      Wired connection 1         8559f62b-0cb9-3935-ba65-b6d57c0043c8  ethernet  --      

Now if I disconnect br-slave-1:

nmcli con down br-slave-1

I get the internet back on the host but then there's no internet on guest and ping still wouldn't work:

So is there a way to use ssh between host and guest while using qemu with kvm, using nmcli or NetworkManager GUI? Many thanks.

Note: As I need to use few different wireless networks on and off, I like to stay away from netplan or network interfaces, hence I'm trying to setup bridge either using nmcli or NetworkManager GUI.

Original post:

I'm trying to SSH into a guest from the host. Both host and guest machines are Ubuntu MATE 21.04.

Internet works just fine both from host and guest machines.

IP addresses:

(1) Router: Asus RT AC68U > 192.168.1.1(2) Host: Ubuntu MATE 21.04 > 192.168.1.106(3) Guest: Ubuntu MATE 21.04 > 192.168.1.139

Firewall have been disabled/stopped on all three:

(1) Router: Asus RT AC68U > SPI Firewall > Disabled(2) Host: Ubuntu MATE 21.04 > sudo systemctl stop nftables(3) Guest: Ubuntu MATE 21.04 > sudo systemctl stop nftables

When I try to ssh-copy-id, I get this error: No route to host

ssh-copy-id admn@192.168.1.139/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed/usr/bin/ssh-copy-id: ERROR: ssh: connect to host 192.168.1.139 port 22: No route to host

So I tried to ping (does not work either way; "host to guest" or "guest to host"):

ping 192.168.1.139PING 192.168.1.139 (192.168.1.139) 56(84) bytes of data.From 192.168.1.106 icmp_seq=1 Destination Host UnreachableFrom 192.168.1.106 icmp_seq=2 Destination Host Unreachable

However ping does work from either "host to router" or "guest to router":

ping from host to router:

ping 192.168.1.1PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.400 ms64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.339 ms

ping from guest to router:

ping 192.168.1.1PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.651 ms64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.625 ms

Host and guest machines are connected through a network bridge br0, which I've created using Netwrok Manager GUI. Bridge br0 have two "bridged connections", br0 slave 1 and br0 slave 2.

Enable STP (spanning Tree Protocol is "unchecked". Though it did not make any difference even I "checked" it.

Additional details which I think would be helpful:

sudo nano /etc/libvirt/qemu/networks/host-bridge.xml<network><name>host-bridge</name><uuid>0ae7be62-9f9e-4346-9309-88985dd0f5ad</uuid><forward mode='bridge'/><bridge name='br0'/></network>virsh net-list --all Name          State    Autostart   Persistent------------------------------------------------ host-bridge   active   yes         yes

Results of ip a and ip r on the host machine:

ip a1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00    inet 127.0.0.1/8 scope host lo       valid_lft forever preferred_lft forever2: enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000    link/ether e0:69:95:4d:7c:9c brd ff:ff:ff:ff:ff:ff    inet 192.168.1.106/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s25       valid_lft 599784sec preferred_lft 599784sec    inet 192.168.1.104/24 brd 192.168.1.255 scope global secondary noprefixroute enp0s25       valid_lft forever preferred_lft forever3: wlxd0374547816a: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000    link/ether d0:37:45:47:81:6a brd ff:ff:ff:ff:ff:ff4: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000    link/ether 96:d5:ab:3c:a7:e8 brd ff:ff:ff:ff:ff:ff7: macvtap2@enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 500    link/ether 52:54:00:1f:6a:cd brd ff:ff:ff:ff:ff:ff    inet 192.168.1.140/24 brd 192.168.1.255 scope global noprefixroute macvtap2       valid_lft forever preferred_lft foreverip r       default via 192.168.1.1 dev enp0s25 proto dhcp src 192.168.1.104 metric 202 default via 192.168.1.1 dev macvtap2 proto dhcp src 192.168.1.140 metric 207 169.254.0.0/16 dev macvtap2 scope link metric 1000 192.168.1.0/24 dev enp0s25 proto dhcp scope link src 192.168.1.104 metric 202 192.168.1.0/24 dev macvtap2 proto dhcp scope link src 192.168.1.140 metric 207 

Results of ip a and ip r on the guest machine:

ip a1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00    inet 127.0.0.1/8 scope host lo       valid_lft forever preferred_lft forever    inet6 ::1/128 scope host        valid_lft forever preferred_lft forever2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000    link/ether 52:54:00:1f:6a:cd brd ff:ff:ff:ff:ff:ff    inet 192.168.1.139/24 brd 192.168.1.255 scope global dynamic noprefixroute enp2s0       valid_lft 603989sec preferred_lft 603989sec    inet6 fe80::d316:3db7:9af5:8d0c/64 scope link noprefixroute        valid_lft forever preferred_lft foreverip rdefault via 192.168.1.1 dev enp2s0 proto dhcp metric 100 169.254.0.0/16 dev enp2s0 scope link metric 1000 192.168.1.0/24 dev enp2s0 proto kernel scope link src 192.168.1.139 metric 100 

NIC details (from Virtual machine manager) of the guest machine:

Virtual Network Interface:Network source: Macvtap deviceDevice name: enp0s25Device model: virtioXML:<interface type="direct"><mac address="52:54:00:1f:6a:cd"/><source dev="enp0s25" mode="bridge"/><target dev="macvtap2"/><model type="virtio"/><alias name="net0"/><address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/></interface>

OS: Ubuntu MATE 21.04

qemu: 1:5.2+dfsg-9ubuntu3

bridge-utils: 1.6-5ubuntu1

virt-manager: 1:3.2.0-3

libvirt-daemon: 7.0.0-2ubuntu2

Thanks alot in advance.

Edit-1:

brctl show br0bridge name bridge id       STP enabled interfacesbr0     8000.96d5ab3ca7e8   no