自定義dhclient配置文件步驟如下：
sudo cp /etc/dhcp/dhclient.conf /etc/dhcp/dhclient.conf.bak
nano或vim）打開配置文件：sudo nano /etc/dhcp/dhclient.conf
request subnet-mask, domain-name-servers, routers;
supersede domain-name-servers 8.8.8.8, 8.8.4.4;
interface "eth0" {
fixed-address 192.168.1.100;
option routers 192.168.1.1;
}
timeout 30;
retry 5;
sudo systemctl restart network # Debian/Ubuntu
sudo systemctl restart isc-dhcp-client # CentOS/RHEL
說明：不同發行版配置文件路徑可能略有差異（如CentOS部分版本需修改/etc/sysconfig/network-scripts/ifcfg-<接口>），具體可通過man dhclient.conf查看詳細語法。
