dhclient应该通过租约声明支持回退，请参见
dhclient.conf手册页。
将类似的内容添加到您的
dhclient.conf
timeout 10;lease {interface "eth0";fixed-address 10.0.0.10;option subnet-mask 255.255.255.0;renew 2 2022/1/1 00:00:01;rebind 2 2022/1/1 00:00:01;expire 2 2022/1/1 0:00:01;}或者您可以为接口分配第二个IP，例如
/etc/network/interfaces
auto loiface lo inet loopbackiface eth0 inet dhcpauto eth0:1iface eth0:1 inet staticaddress 10.10.10.2netmask 255.255.255.0
