linux开机本来非常快的，可是不知道什么原因，突然变慢了，通过开机的观察，发现了这段
Listining on LPF/eth0/00:1c:33:33:a7:c0
Sending on LPF/eth0/00:1c:33:33:a7:c0
Sending on Sachet/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 3
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 6
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 11
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 15
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 7
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 18
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 internal 1
NO DHCPOFFERS recieved
No working leases in persistant databases - sleepeng
大概会持续30s的样子
google了一下，找到了一种解决方法，
首先
vi /etc/network/interfaces
如下
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet dhcp
~
你只需把最后两行删掉就可以了，变成
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
好，现在重新开机，是不是速度非常快了啊，
我的直接加快了30s啊 30s！！！！！！！！！！！！！！
（说明：如果你是在wifi或校园网下上网，那么非常建议你这样改，ASDL下没实验）
解决debian下开机慢（DHCPDISCOVER on eth0）,布布扣,bubuko.com
解决debian下开机慢（DHCPDISCOVER on eth0）
原文：http://blog.csdn.net/pyufftj/article/details/21462525