查看/更新DHCP租约到期时间（Linux系统）

1. 在控制台修改子网DHCP租约时间后，登录待刷新租约的云服务器。
2. 执行以下命令，确认提供DHCP服务的客户端为dhclient。

   ps -ef | grep dhclient

   • 回显类似如下信息，表示存在dhclient对应进程，说明客户端是dhclient。其中-lf参数后，类型为lease的文件中存有租约信息。

     [root@ecs-A ~]# ps -ef | grep dhclient
     root       580   526  0 18:49 ?        00:00:00 /sbin/dhclient -d -q -sf /usr/libexec/nm-dhcp-helper -pf /var/run/dhclient-eth0.pid -lf /var/lib/NetworkManager/dhclient-5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03-eth0.lease -cf /var/lib/NetworkManager/dhclient-eth0.conf eth0
     root      1512  1470  0 18:50 pts/0    00:00:00 grep --color=auto dhclient

   • 如果不存在dhclient进程，则本文档可能不适用，请您查找对应DHCP客户端的操作指令。
3. 执行以下命令，查看2的lease文件中当前DHCP租约信息。

   cat lease文件名称

   命令示例：

   cat /var/lib/NetworkManager/dhclient-5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03-eth0.lease

   回显类似如下信息，lease文件中会保存历史DHCP租约信息，最后一个是最新的DHCP租约信息。

   [root@ecs-A ~]# cat /var/lib/NetworkManager/dhclient-5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03-eth0.lease
   lease {
     interface "eth0";
     fixed-address 172.16.0.54;
     option subnet-mask 255.255.255.0;
     option dhcp-lease-time 108000000;
     option routers 172.16.0.1;
     option dhcp-message-type 5;
     option dhcp-server-identifier 172.16.0.254;
     option domain-name-servers 100.125.1.250,100.125.64.250;
     option interface-mtu 1500;
     option dhcp-renewal-time 54000000;
     option dhcp-rebinding-time 94500000;
     option rfc3442-classless-static-routes 0,172,16,0,1,32,169,254,169,254,172,16,0,1;
     option broadcast-address 172.16.0.255;
     option host-name "host-172-16-0-54";
     option domain-name "openstacklocal";
     renew 3 2025/06/18 21:46:42;
     rebind 3 2027/01/20 04:46:44;
     expire 5 2027/06/25 10:46:44;
   }
   lease {
     interface "eth0";
     fixed-address 172.16.0.54;
     option subnet-mask 255.255.255.0;
     option routers 172.16.0.1;
     option dhcp-lease-time 108000000;
     option dhcp-message-type 5;
     option domain-name-servers 100.125.1.250,100.125.64.250;
     option dhcp-server-identifier 172.16.0.254;
     option interface-mtu 1500;
     option dhcp-renewal-time 54000000;
     option broadcast-address 172.16.0.255;
     option rfc3442-classless-static-routes 0,172,16,0,1,32,169,254,169,254,172,16,0,1;
     option dhcp-rebinding-time 94500000;
     option host-name "host-172-16-0-54";
     option domain-name "openstacklocal";
     renew 3 2025/08/20 23:57:15;
     rebind 3 2027/01/20 04:50:00;
     expire 5 2027/06/25 10:50:00;
   }

4. 执行以下命令，释放当前云服务器的IP地址。

   dhclient -r

5. 执行以下命令，获取新的DHCP租约。

   killall dhclient && systemctl restart NetworkManager

6. 执行以下命令，查看2的lease文件中最新的DHCP租约信息。

   cat lease文件名称

   命令示例：

   cat /var/lib/NetworkManager/dhclient-5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03-eth0.lease

   回显类似如下信息，lease文件中会保存历史DHCP租约信息，最后一个是更新后的DHCP租约信息。

   [root@ecs-A ~]# cat /var/lib/NetworkManager/dhclient-5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03-eth0.lease
   lease {
     interface "eth0";
     fixed-address 172.16.0.54;
     option subnet-mask 255.255.255.0;
     option dhcp-lease-time 108000000;
     option routers 172.16.0.1;
     option dhcp-message-type 5;
     option dhcp-server-identifier 172.16.0.254;
     option domain-name-servers 100.125.1.250,100.125.64.250;
     option interface-mtu 1500;
     option dhcp-renewal-time 54000000;
     option dhcp-rebinding-time 94500000;
     option rfc3442-classless-static-routes 0,172,16,0,1,32,169,254,169,254,172,16,0,1;
     option broadcast-address 172.16.0.255;
     option host-name "host-172-16-0-54";
     option domain-name "openstacklocal";
     renew 3 2025/08/20 23:57:15;
     rebind 3 2027/01/20 04:50:00;
     expire 5 2027/06/25 10:50:00;
   }
   lease {
     interface "eth0";
     fixed-address 172.16.0.54;
     option subnet-mask 255.255.255.0;
     option routers 172.16.0.1;
     option dhcp-lease-time 108000000;
     option dhcp-message-type 5;
     option domain-name-servers 100.125.1.250,100.125.64.250;
     option dhcp-server-identifier 172.16.0.254;
     option interface-mtu 1500;
     option dhcp-renewal-time 54000000;
     option broadcast-address 172.16.0.255;
     option rfc3442-classless-static-routes 0,172,16,0,1,32,169,254,169,254,172,16,0,1;
     option dhcp-rebinding-time 94500000;
     option host-name "host-172-16-0-54";
     option domain-name "openstacklocal";
     renew 4 2025/07/03 00:34:04;
     rebind 3 2027/01/20 04:52:43;
     expire 5 2027/06/25 10:52:43;
   }Sub-eni