编辑：由于macvtap无法用于主机和客户机之间的通信，我尝试使用bridge，但主机上没有互联网，并且ping仍然ssh不起作用。
这就是我创建的方式bridge：
nmcli connection add type bridge ifname br0
Output:
Connection 'bridge-br0' (bf1406b0-4ea8-4338-9edc-0f58fd019bec) successfully added.
nmcli con add type ethernet con-name br-slave-1 ifname enp0s25 master br0
nmcli con add type ethernet con-name br-slave-1 ifname enp0s25 master br0
nmcli con modify bridge-br0 bridge.stp no
nmcli connection add type ethernet ifname bridge-br0 ipv4.method auto
Output:
Connection 'ethernet-bridge-br0' (6c2c5495-6e43-4cd5-a574-014042987781) successfully added.
After reboot:
nmcli con show
NAME 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 --
现在如果我断开连接br-slave-1：
nmcli con down br-slave-1
我恢复了主机上的互联网连接，但客户机上却没有互联网连接，并且 ping 仍然不工作：
那么在使用 qemu 和 kvm 时，有没有办法ssh在主机和客户机之间使用，使用nmcli或NetworkManager GUI？非常感谢。
笔记：由于我需要断断续续地使用几个不同的无线网络，我喜欢远离netplan或network interfaces，因此我尝试使用或来设置nmcli桥接NetworkManager GUI。
原始帖子：
我正在尝试从主机通过 SSH 进入客户机。主机和客户机都是 Ubuntu MATE 21.04。
互联网在主机和客户机上均可正常运行。
IP 地址：
(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
防火墙已在所有三个设备上被禁用/停止：
(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
当我尝试时ssh-copy-id，出现此错误：No route to host
ssh-copy-id [email protected]
/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
所以我尝试了ping（无论哪种方式都不起作用；“主人对客人”或“客人对主人”）：
ping 192.168.1.139
PING 192.168.1.139 (192.168.1.139) 56(84) bytes of data.
From 192.168.1.106 icmp_seq=1 Destination Host Unreachable
From 192.168.1.106 icmp_seq=2 Destination Host Unreachable
但是，ping无论是从“主机到路由器”还是“访客到路由器”都可以工作：
ping从主机到路由器：
ping 192.168.1.1
PING 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 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.339 ms
ping从客户机到路由器：
ping 192.168.1.1
PING 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 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.625 ms
主机和客户机通过网络桥接器连接br0，这是我使用 Netwrok Manager GUI 创建的。网桥br0有两个“桥接连接”，br0 slave 1和br0 slave 2。
Enable STP (spanning Tree Protocol是“未选中”的。尽管我“选中”了它，但并没有什么不同。
我认为其他详细信息可能会有帮助：
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
主机上ip a的结果：ip r
ip a
1: 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
2: 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 forever
3: 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:ff
4: 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:ff
7: 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 forever
ip 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
客户机上ip a的结果：ip r
ip a
1: 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 forever
2: 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 forever
ip r
default 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
客户机的 NIC 详细信息（来自虚拟机管理器）：
Virtual Network Interface:
Network source: Macvtap device
Device name: enp0s25
Device model: virtio
XML:
<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>
操作系统：Ubuntu MATE 21.04
qemu：1：5.2+dfsg-9ubuntu3
桥接实用程序：1.6-5ubuntu1
virt-manager：1：3.2.0-3
libvirt 守护进程：7.0.0-2ubuntu2
提前致谢。
編輯-1：
brctl show br0
bridge name bridge id STP enabled interfaces
br0 8000.96d5ab3ca7e8 no
答案1
我原本希望您的虚拟机使用您的网桥 br0 作为所需的通信方法。我正在运行 3 个虚拟机并得到：
doug@s19:~$ brctl show br0
bridge name bridge id STP enabled interfaces
br0 8000.3c7c3f0d9983 no enp3s0
vnet0
vnet1
vnet2
在主机上：
doug@s19:~$ ip addr
1: 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
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br0 state UP group default qlen 1000
link/ether 3c:7c:3f:0d:99:83 brd ff:ff:ff:ff:ff:ff
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 3c:7c:3f:0d:99:83 brd ff:ff:ff:ff:ff:ff
inet 192.168.111.136/24 brd 192.168.111.255 scope global dynamic br0
valid_lft 45219sec preferred_lft 45219sec
4: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:22:2f:dc brd ff:ff:ff:ff:ff:ff
5: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:60:ea:3e brd ff:ff:ff:ff:ff:ff
6: vnet2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:60:ea:5e brd ff:ff:ff:ff:ff:ff
使用我的 netplan 网络文件/etc/netplan/01-netcfg.yaml：
# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
version: 2
renderer: networkd
ethernets:
enp3s0:
dhcp4: no
bridges:
br0:
interfaces: [ enp3s0 ]
dhcp4: yes
以及虚拟机的.xml 定义文件之一的相关部分：
<interface type='bridge'>
<mac address='52:54:00:22:2f:dc'/>
<source bridge='br0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>