Ubuntu虚拟机通过libvirt/QEMU获取非预期DHCP地址（10.0.2.15）的问题求助
2026-4-21
Ubuntu虚拟机通过libvirt/QEMU获取非预期DHCP地址（10.0.2.15）的问题求助
我在RedHat主机上配置了libvirt的默认网络，virbr0网桥已经启动，网络设置为NAT模式，DHCP地址池是192.168.122.2-254，还专门加了规则给名为fw-core的Ubuntu虚拟机分配固定IP192.168.122.2。但奇怪的是，虚拟机里的dhclient拿到的却是10.0.2.15，完全不是我配置的网段。
主机端验证信息
网桥状态
brctl show
输出：
bridge name bridge id STP enabled interfaces virbr0 8000.52540024cafa yes virbr0-nic
virbr0的IP配置
ip addr show virbr0|grep inet
输出：
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
虚拟机列表
virsh list --all
输出：
Id Name State --------------------------------------------------- 2 fw-core running
默认网络XML配置
sudo virsh net-dumpxml default
输出：
<network> <name>default</name> <uuid>b270007c-ada2-4c16-9b34-3abecc1c4b94</uuid> <forward mode='nat'> <nat> <port start='1024' end='65535'/> </nat> </forward> <bridge name='virbr0' stp='on' delay='0'/> <mac address='52:54:00:24:ca:fa'/> <ip address='192.168.122.1' netmask='255.255.255.0'> <dhcp> <range start='192.168.122.2' end='192.168.122.254'/> <host mac='52:54:00:6d:e4:ae' name='fw-core' ip='192.168.122.2'/> </dhcp> </ip> </network>
虚拟机端异常表现
我能通过virsh console fw-core连接到虚拟机，但无法用SSH连接10.0.2.15。看起来虚拟机完全跳过了virbr0网桥，从企业网络拿到了IP？dhclient是从10.0.2.2获取的地址，而不是我配置的192.168.122.1，而且我也没法从主机用分配的固定IP连接虚拟机。
虚拟机执行dhclient的输出
sudo dhclient -v ens3
输出：
Listening on LPF/ens3/52:54:00:6d:e4:ae Sending on LPF/ens3/52:54:00:6d:e4:ae Sending on Socket/fallback DHCPDISCOVER on ens3 to 255.255.255.255 port 67 interval 3 (xid=0xf27cb27a) DHCPOFFER of 10.0.2.15 from 10.0.2.2 DHCPREQUEST for 10.0.2.15 on ens3 to 255.255.255.255 port 67 (xid=0x7ab27cf2) DHCPACK of 10.0.2.15 from 10.0.2.2 (xid=0xf27cb27a) bound to 10.0.2.15 -- renewal in 32873 seconds.
强制指定DHCP服务器的尝试（失败）
sudo dhclient -v ens3 -s 192.168.122.1
输出：
Internet Systems Consortium DHCP Client 4.4.1 Copyright 2004-2018 Internet Systems Consortium. All rights reserved. Listening on LPF/ens3/52:54:00:6d:e4:ae Sending on LPF/ens3/52:54:00:6d:e4:ae Sending on Socket/fallback DHCPREQUEST for 10.0.2.15 on ens3 to 192.168.122.1 port 67 (xid=0x1557fbe4) DHCPREQU
其他奇怪的现象
虚拟机可以正常访问外网，也能连接主机的SSH服务：
curl -s google.com|sed 1q
输出：
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
sleep 1 | telnet 192.168.122.1 22
输出：
Trying 192.168.122.1... Connected to 192.168.122.1. Escape character is '^]'. SSH-2.0-OpenSSH_7.4 Connection closed by foreign host
虚拟机内部的SSH服务也正常运行：
sleep 1|telnet localhost 22
输出：
Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.4 Connection closed by foreign host.
防火墙排查情况
我怀疑是主机防火墙的问题，已经把virbr0加到了internal区域：
sudo firewall-cmd --zone=internal --list-all
输出：
internal (active) target: default icmp-block-inversion: no interfaces: virbr0 sources: services: dhcp dhcpv6-client mdns samba-client ssh ports: 67/tcp 67/udp protocols: masquerade: no forward-ports: source-ports: icmp-blocks: rich rules:
主机所有网卡信息
ip addr
输出：
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: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000 link/ether 0a:6c:8e:88:52:62 brd ff:ff:ff:ff:ff:ff 3: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 3c:ec:ef:d1:18:54 brd ff:ff:ff:ff:ff:ff inet 10.48.86.33/24 brd 10.48.86.255 scope global noprefixroute eno1 valid_lft forever preferred_lft forever inet6 fe80::310c:bed0:9e4f:f53d/64 scope link noprefixroute valid_lft forever preferred_lft forever 4: eno2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000 link/ether 3c:ec:ef:d1:18:55 brd ff:ff:ff:ff:ff:ff 13: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000 link/ether 52:54:00:24:ca:fa 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 14: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000 link/ether 52:54:00:24:ca:fa brd ff:ff:ff:ff:ff:ff
再次确认网桥状态
brctl show
输出：
bridge name bridge id STP enabled interfaces virbr0 8000.52540024cafa yes virbr0-nic
虚拟机创建命令
我是用这条命令创建的虚拟机：
virt-install --name core --ram $((1024*4)) --file=fw-core.img --file=ubuntu-22.04.3-live-server-amd64.iso
备注：内容来源于stack exchange，提问作者Will
