我在 qemu 上设置网络时遇到了一些问题。我正在尝试简单选项（用户）。我运行的 qemu 命令如下：
./qemu-xilinx/arm-softmmu/qemu-system-arm \
-M xilinx-zynq-a9 -m 1024 -serial null -serial mon:stdio \
-dtb /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources/devicetree.dtb \
-kernel /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources/zImage \
-initrd /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources.qemu/ramdisk.img \
-nographic -s -net dump,file=/tmp/dhcpdump.pcap -net nic \
-net user,net=192.168.1.0/24
该命令最有趣的部分在最后。我基本上将所有 TCP/UDP 流量转储到/tmp/dhcpdump.pcap。
然后从 qemu 我执行以下操作：
$ udhcpc -t 1 -T 10 -n
udhcpc (v1.22.0.git) started
Sending discover...
No lease, failing
我从主机使用 thcpdump 读取了转储信息：
(host) $ tcpdump -e -v -s 0 -nr /tmp/dhcpdump.pca
[*other very similar requests done by the kernel at startup*]
15:00:48.874298 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: (tos 0x10, ttl 64, id 20, offset 0, flags [none], proto UDP (17), length 576)
192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548, xid 0x7a5d3455, Flags [none]
Your-IP 192.168.1.15
Server-IP 192.168.1.2
Client-Ethernet-Address 4a:3d:06:fb:d3:52
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Offer
Server-ID Option 54, length 4: 192.168.1.2
Subnet-Mask Option 1, length 4: 255.255.255.0
Default-Gateway Option 3, length 4: 192.168.1.2
Domain-Name-Server Option 6, length 4: 192.168.1.3
Lease-Time Option 51, length 4: 86400
15:00:48.874348 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 312)
0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284, xid 0x7a5d3455, Flags [none]
Client-Ethernet-Address 4a:3d:06:fb:d3:52
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether 4a:3d:06:fb:d3:52
MSZ Option 57, length 2: 576
Parameter-Request Option 55, length 7:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
Domain-Name, BR, NTP
Vendor-Class Option 60, length 16: "udhcp 1.22.0.git"
问题是我无法获得租约，但从学术角度来看，我最感兴趣的是为什么我在客户问题发现之前就得到了报价。
编辑：这里也是完整的转储：
(host) $ tcpdump -e -s 0 -nr /tmp/dhcpdump.pcap
reading from file /tmp/dhcpdump.pcap, link-type EN10MB (Ethernet)
14:34:12.400162 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:12.400203 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:34:14.518984 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:14.519023 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:34:18.227926 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:18.227976 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:34:24.718934 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:24.719064 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:34:36.072184 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:36.072301 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:34:55.938462 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:34:55.938583 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:21.051476 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:21.051526 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:22.872058 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:22.872175 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:26.055294 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:26.055339 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:31.619870 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:31.619966 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:41.351737 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:41.351798 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:35:58.377559 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:35:58.377601 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 548
14:51:15.522553 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:51:15.522601 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
14:51:18.060428 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:51:18.060460 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
14:52:22.487889 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:52:22.487939 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
14:52:30.883654 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:52:30.883691 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
14:52:39.279423 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:52:39.279462 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
14:59:42.818215 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
14:59:42.818263 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
15:00:07.938782 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
15:00:07.938829 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
15:00:28.348337 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
15:00:28.348378 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284
15:00:48.874298 52:55:c0:a8:01:02 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590: 192.168.1.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 548
15:00:48.874348 4a:3d:06:fb:d3:52 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 326: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 4a:3d:06:fb:d3:52, length 284