我正在使用 Ubuntu 16.04.2 和 KVM QEMU。
我将虚拟机配置为桥接（即，它们应该从 DHCP 服务器获取自己的 IP 并在网络上显示为单独的主机。）
但是，他们没有获得任何连接。我无法从他们那里 ping 通，也无法 ping 通他们。如果他们无法获得 DHCP 租约，我本以为他们会获得 169.xxx IP，但他们根本没有获得任何 IP。
我不知道为什么，而且我也无法修复它。如果无法让它工作，我会格式化机器并重新安装所有内容，但我更愿意了解问题所在并修复它。
以下是在主机上运行的相关命令及其输出：
$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
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: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br0 state UP group default qlen 1000
link/ether 00:1d:09:0b:87:6d brd ff:ff:ff:ff:ff:ff
inet6 fe80::21d:9ff:fe0b:876d/64 scope link
valid_lft forever preferred_lft forever
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:1d:09:0b:87:6d brd ff:ff:ff:ff:ff:ff
inet 192.168.1.129/24 brd 192.168.1.255 scope global br0
valid_lft forever preferred_lft forever
inet6 fe80::21d:9ff:fe0b:876d/64 scope link
valid_lft forever preferred_lft forever
4: br-0e57a29cd0f7: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:2b:9a:39:d6 brd ff:ff:ff:ff:ff:ff
inet 172.18.0.1/16 scope global br-0e57a29cd0f7
valid_lft forever preferred_lft forever
5: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:ed:8f:cb:c1 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 scope global docker0
valid_lft forever preferred_lft forever
inet6 fe80::42:edff:fe8f:cbc1/64 scope link
valid_lft forever preferred_lft forever
8: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 52:54:00:41:79:0f brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
valid_lft forever preferred_lft forever
9: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000
link/ether 52:54:00:41:79:0f brd ff:ff:ff:ff:ff:ff
16: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:81:08:d0 brd ff:ff:ff:ff:ff:ff
inet6 fe80::fc54:ff:fe81:8d0/64 scope link
valid_lft forever preferred_lft forever
32: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:72:c2:db brd ff:ff:ff:ff:ff:ff
inet6 fe80::fc54:ff:fe72:c2db/64 scope link
valid_lft forever preferred_lft forever
34: vethbae4bfe@if33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default
link/ether 72:a8:cd:d9:9c:fe brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::70a8:cdff:fed9:9cfe/64 scope link
valid_lft forever preferred_lft forever
$ ip l
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br0 state UP mode DEFAULT group default qlen 1000
link/ether 00:1d:09:0b:87:6d brd ff:ff:ff:ff:ff:ff
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether 00:1d:09:0b:87:6d brd ff:ff:ff:ff:ff:ff
4: br-0e57a29cd0f7: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default
link/ether 02:42:2b:9a:39:d6 brd ff:ff:ff:ff:ff:ff
5: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default
link/ether 02:42:ed:8f:cb:c1 brd ff:ff:ff:ff:ff:ff
8: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
link/ether 52:54:00:41:79:0f brd ff:ff:ff:ff:ff:ff
9: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN mode DEFAULT group default qlen 1000
link/ether 52:54:00:41:79:0f brd ff:ff:ff:ff:ff:ff
16: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UNKNOWN mode DEFAULT group default qlen 1000
link/ether fe:54:00:81:08:d0 brd ff:ff:ff:ff:ff:ff
32: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UNKNOWN mode DEFAULT group default qlen 1000
link/ether fe:54:00:72:c2:db brd ff:ff:ff:ff:ff:ff
34: vethbae4bfe@if33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP mode DEFAULT group default
link/ether 72:a8:cd:d9:9c:fe brd ff:ff:ff:ff:ff:ff link-netnsid 0
$ brctl show
bridge name bridge id STP enabled interfaces
br-0e57a29cd0f7 8000.02422b9a39d6 no
br0 8000.001d090b876d no enp4s0
vnet0
vnet1
docker0 8000.0242ed8fcbc1 no vethbae4bfe
virbr0 8000.52540041790f yes virbr0-nic
$ virsh net-list --all
Name State Autostart Persistent
----------------------------------------------------------
default active yes yes
$ virsh net-dumpxml default
<network>
<name>default</name>
<uuid>42aa6628-f6c8-4169-9b38-1f6f5cbb7a04</uuid>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<bridge name='virbr0' stp='on' delay='0'/>
<mac address='52:54:00:41:79:0f'/>
<ip address='192.168.122.1' netmask='255.255.255.0'>
<dhcp>
<range start='192.168.122.2' end='192.168.122.254'/>
</dhcp>
</ip>
</network>
$ virsh dumpxml downloader
<domain type='kvm' id='9'>
<name>downloader</name>
<uuid>9241d93d-b403-4347-bdda-002b5ee8f344</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>524288</currentMemory>
<vcpu placement='static'>2</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-i440fx-xenial'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
</features>
<cpu mode='custom' match='exact'>
<model fallback='allow'>core2duo</model>
</cpu>
<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-spice</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/media/storage/vm_disks/downloader.img'/>
<backingStore/>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<alias name='usb'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<alias name='usb'/>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<alias name='usb'/>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<alias name='usb'/>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pci-root'>
<alias name='pci.0'/>
</controller>
<controller type='virtio-serial' index='0'>
<alias name='virtio-serial0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:72:c2:db'/>
<source bridge='br0'/>
<target dev='vnet1'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/2'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/2'>
<source path='/dev/pts/2'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<channel type='spicevmc'>
<target type='virtio' name='com.redhat.spice.0' state='disconnected'/>
<alias name='channel0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='spice' port='5901' autoport='yes' listen='127.0.0.1'>
<listen type='address' address='127.0.0.1'/>
<image compression='off'/>
</graphics>
<sound model='ich6'>
<alias name='sound0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</sound>
<video>
<model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
<redirdev bus='usb' type='spicevmc'>
<alias name='redir0'/>
</redirdev>
<redirdev bus='usb' type='spicevmc'>
<alias name='redir1'/>
</redirdev>
<memballoon model='virtio'>
<stats period='5'/>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</memballoon>
</devices>
<seclabel type='dynamic' model='apparmor' relabel='yes'>
<label>libvirt-9241d93d-b403-4347-bdda-002b5ee8f344</label>
<imagelabel>libvirt-9241d93d-b403-4347-bdda-002b5ee8f344</imagelabel>
</seclabel>
</domain>
$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
# auto enp4s0
# iface enp4s0 inet manual
# VMs bridge
auto br0
iface br0 inet dhcp
bridge_ports enp4s0
bridge_stp off
bridge_fd 0
bridge_maxwait 0
`$ virsh net-start 默认
error: Failed to start network default
error: Requested operation is not valid: network is already active
$ ip route
default via 192.168.1.1 dev br0
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1
172.18.0.0/16 dev br-0e57a29cd0f7 proto kernel scope link src 172.18.0.1 linkdown
192.168.1.0/24 dev br0 proto kernel scope link src 192.168.1.129
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
$ iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
DROP all -- 221.7.38.200 anywhere
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:bootps
ACCEPT tcp -- anywhere anywhere tcp dpt:bootps
f2b-sshd tcp -- anywhere anywhere multiport dports ssh
Chain FORWARD (policy DROP)
target prot opt source destination
ACCEPT all -- anywhere 192.168.122.0/24 ctstate RELATED,ESTABLISHED
ACCEPT all -- 192.168.122.0/24 anywhere
ACCEPT all -- anywhere anywhere
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
DOCKER-ISOLATION all -- anywhere anywhere
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:bootpc
Chain DOCKER (2 references)
target prot opt source destination
ACCEPT tcp -- anywhere 172.17.0.2 tcp dpt:http
Chain DOCKER-ISOLATION (1 references)
target prot opt source destination
DROP all -- anywhere anywhere
DROP all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain f2b-sshd (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere