我有一个 libvirt KVM VM（名为 netstuff）通过网桥（br0）运行，它有两个从属设备：（em2）主机物理接口和（vnet0）虚拟网卡。 dnsmasq-dhcp 位于主机上，为虚拟机和其他物理主机提供 IP 地址。
我可以路由 192.168.1.0/24 上的任何位置，包括虚拟机和硬件之间，但虚拟机无法路由到其他网络或 Internet。当来自访客的流量退出到主机时，它似乎没有从网桥路由到具有默认路由的接口 em1。
帮助？
主机 libvirt XML：
# virsh dumpxml netstuff
... snip ...
<interface type='bridge'>
<mac address='52:54:00:27:c4:22'/>
<source bridge='br0'/>
<target dev='vnet0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
... snip ...
主机IP路由：
# ip r
default via XXX.99.126.1 dev em1
169.254.0.0/16 dev em1 scope link metric 1002
169.254.0.0/16 dev br0 scope link metric 1004
192.168.1.0/24 dev br0 proto kernel scope link src 192.168.1.1
XXX.99.126.0/27 dev em1 proto kernel scope link src XXX.99.126.4
主机网卡：
# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 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: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
link/ether d4:ae:52:9d:73:c2 brd ff:ff:ff:ff:ff:ff
inet XXX.99.126.4/27 brd XXX.99.126.31 scope global em1
valid_lft forever preferred_lft forever
inet6 fe80::d6ae:52ff:fe9d:73c2/64 scope link
valid_lft forever preferred_lft forever
3: em2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br0 state UP qlen 1000
link/ether d4:ae:52:9d:73:c3 brd ff:ff:ff:ff:ff:ff
inet6 fe80::d6ae:52ff:fe9d:73c3/64 scope link
valid_lft forever preferred_lft forever
4: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
link/ether d4:ae:52:9d:73:c3 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.1/24 brd 192.168.1.255 scope global br0
valid_lft forever preferred_lft forever
inet6 fe80::d6ae:52ff:fe9d:73c3/64 scope link
valid_lft forever preferred_lft forever
5: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UNKNOWN qlen 1000
link/ether fe:54:00:27:c4:22 brd ff:ff:ff:ff:ff:ff
inet6 fe80::fc54:ff:fe27:c422/64 scope link
valid_lft forever preferred_lft forever
主机ip表：
# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
INPUT_direct all -- anywhere anywhere
INPUT_ZONES_SOURCE all -- anywhere anywhere
INPUT_ZONES all -- anywhere anywhere
DROP all -- anywhere anywhere ctstate INVALID
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere PHYSDEV match --physdev-is-bridged
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
FORWARD_direct all -- anywhere anywhere
FORWARD_IN_ZONES_SOURCE all -- anywhere anywhere
FORWARD_IN_ZONES all -- anywhere anywhere
FORWARD_OUT_ZONES_SOURCE all -- anywhere anywhere
FORWARD_OUT_ZONES all -- anywhere anywhere
DROP all -- anywhere anywhere ctstate INVALID
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
OUTPUT_direct all -- anywhere anywhere
Chain FORWARD_IN_ZONES (1 references)
target prot opt source destination
FWDI_public all -- anywhere anywhere [goto]
FWDI_public all -- anywhere anywhere [goto]
FWDI_public all -- anywhere anywhere [goto]
Chain FORWARD_IN_ZONES_SOURCE (1 references)
target prot opt source destination
Chain FORWARD_OUT_ZONES (1 references)
target prot opt source destination
FWDO_public all -- anywhere anywhere [goto]
FWDO_public all -- anywhere anywhere [goto]
FWDO_public all -- anywhere anywhere [goto]
Chain FORWARD_OUT_ZONES_SOURCE (1 references)
target prot opt source destination
Chain FORWARD_direct (1 references)
target prot opt source destination
Chain FWDI_public (3 references)
target prot opt source destination
FWDI_public_log all -- anywhere anywhere
FWDI_public_deny all -- anywhere anywhere
FWDI_public_allow all -- anywhere anywhere
ACCEPT icmp -- anywhere anywhere
Chain FWDI_public_allow (1 references)
target prot opt source destination
Chain FWDI_public_deny (1 references)
target prot opt source destination
Chain FWDI_public_log (1 references)
target prot opt source destination
Chain FWDO_public (3 references)
target prot opt source destination
FWDO_public_log all -- anywhere anywhere
FWDO_public_deny all -- anywhere anywhere
FWDO_public_allow all -- anywhere anywhere
Chain FWDO_public_allow (1 references)
target prot opt source destination
Chain FWDO_public_deny (1 references)
target prot opt source destination
Chain FWDO_public_log (1 references)
target prot opt source destination
Chain INPUT_ZONES (1 references)
target prot opt source destination
IN_public all -- anywhere anywhere [goto]
IN_public all -- anywhere anywhere [goto]
IN_public all -- anywhere anywhere [goto]
Chain INPUT_ZONES_SOURCE (1 references)
target prot opt source destination
Chain INPUT_direct (1 references)
target prot opt source destination
REJECT tcp -- anywhere anywhere multiport dports ssh match-set fail2ban-sshd src reject-with icmp-port-unreachable
Chain IN_public (3 references)
target prot opt source destination
IN_public_log all -- anywhere anywhere
IN_public_deny all -- anywhere anywhere
IN_public_allow all -- anywhere anywhere
ACCEPT icmp -- anywhere anywhere
Chain IN_public_allow (1 references)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:bootps ctstate NEW
ACCEPT tcp -- anywhere anywhere tcp dpt:ssh ctstate NEW
Chain IN_public_deny (1 references)
target prot opt source destination
Chain IN_public_log (1 references)
target prot opt source destination
Chain OUTPUT_direct (1 references)
target prot opt source destination
访客ip路由：
ssh [email protected]
Last login: Sat Apr 8 05:29:55 2017 from 192.168.1.1
[centos@netstuff ~]$ ip r
default via 192.168.1.1 dev eth0
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.76
[centos@netstuff ~]$
访客 NIC：
[centos@netstuff ~]$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:27:c4:22 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.76/24 brd 192.168.1.255 scope global dynamic eth0
valid_lft 2978sec preferred_lft 2978sec
inet6 fe80::5054:ff:fe27:c422/64 scope link
valid_lft forever preferred_lft forever
答案1
事实证明，如果没有 NAT，这是不可能的，所以我default使用 重新启用了 NAT 网络virsh net-start default。 libvirt 使用 dnsmasq 时要小心，让 DHCP 服务器仅在它创建的接口上运行。所以我只是确保我在主机上设置的 dnsmasq 不会干扰 libvirt 创建的 dnsmasq。为此，/etc/dnsmasq.conf我将 dnsmasq 设置为bind-interfaces模式，并通过指示我给它的静态 IP 来强制它监听我创建的网桥 (br0)：192.168.1.1
listen-address=192.168.1.1
bind-interfaces
而且当然：
systemctl restart dnsmasq
请参阅此处了解 dnsmasq 常见问题解答以及“绑定接口”和“绑定动态”设置。 http://www.thekelleys.org.uk/dnsmasq/docs/FAQ