DHCP 和只读根文件系统

Question

在安装为只读（嵌入式计算机）ifup wlan0的系统上执行操作时，出现/此错误：

Failed to connect to non-global ctrl_ifname: wlan0  error: Read-only file system
Internet Systems Consortium DHCP Client 4.3.1
Copyright 2004-2014 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

can't create /var/lib/dhcp/dhclient.wlan0.leases: Read-only file system
Listening on LPF/wlan0/80:1f:02:d3:42:b8
Sending on   LPF/wlan0/80:1f:02:d3:42:b8
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 13
...
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

另一方面，当ifup wlan0以/读写方式挂载时，没问题，成功归因于IP。

如何使 DHCP 在只读根文件系统上工作？

---

# /etc/network/interfaces

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-ssid "<myssid>"
wpa-psk "<mypasswd>"

Answer 1

在 RAM 中创建一个 tmpfs 分区，然后将 /var/lib/dh​​cp 符号链接到其中的目录。

编辑：我假设您可以在将根文件系统更改为只读之前对其进行编辑。所以：

1. 设置一个 tmpfs 挂载点 mkdir /mnt/ramdisk && mkdir /mnt/ramdisk/var-lib-dhcp
2. 将 tmpfs 添加到您的 fstab 中 tmpfs /mnt/ramdisk/var-lib-dhcp tmpfs size=10M 0 0
3. 添加一个符号链接从/var/lib/dhcp到/mnt/ramdisk/var-lib-dhcp
4. 在文件系统读/写时测试
5. 将文件系统设为只读，再次测试