错误： 在Vmware/virtualbox上新建一个拷贝的Red Hat Enterprise Linux虚拟机，启动时发现找不到网卡（上不去网）：

[root[@primary](https://my.oschina.net/primary) ~]# service network restartShutting down loopback interface:                          [  OK  ]Bringing up loopback interface:                               [  OK  ]Bringing up interface eth0:  Device eth1 does not seem to be present, delaying initialization.                                                                                [FAILED]

错误原因： 克隆的Linux系统在新的机器上运行，新服务器网卡物理地址已经改变。而/etc/udev/rules.d/70-persistent-net.rules这个文件确定了网卡和MAC地址的信息之间的绑定，克隆后的网卡的MAC已经发生了变化，所以导致系统认为网络设备不存在，网络不能正常启动。另外一个就是/etc/sysconfig/network-scripts/ifcfg-eth0里面MAC地址也是以前的旧信息。 关于/etc/udev/rules.d/70-persistent-net.rules这个文件，系统在启动时会自动监测变化，然后由/lib/udev/write_net_rules写入到/etc/udev/rules.d/70-persistent-net.rules中一个新的配置节，网卡的的序号依次递增（如原来为eth0,则修改第一后生成一个eth1,再次修改后生成一个eth2...）,且其ATTR{address}的值为当前网卡对应的mac地址。

[root[@primary](https://my.oschina.net/primary) ~]# vi /etc/udev/rules.d/70-persistent-net.rules # This file was automatically generated by the /lib/udev/write_net_rules# program, run by the persistent-net-generator.rules rules file.## You can modify it, as long as you keep each rule on a single# line, and change only the value of the NAME= key.# PCI device 0x8086:0x100e (e1000)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:2a:c4:f0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"# PCI device 0x8086:0x100e (e1000)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:1d:6d:0e", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"# PCI device 0x8086:0x100e (e1000)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:8e:51:f6", ATTR{type}=="1", KERNEL=="eth*", NAME="eth2"~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          "/etc/udev/rules.d/70-persistent-net.rules" 14L, 750C

[root ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0 看到里面配置的的确是eth1的旧信息，实际是需要配置为最新的eth2的信息。

解决方法： 1.编辑/etc/sysconfig/network-scripts/ifcfg-eth0配置文件，修改为eth2的配置信息并设置为静态：DEVICE=eth2, BOOTPROTO=static, HWADDR=08:00:27:8e:51:f6 2.重启网卡服务成功即可。

[root[@primary](https://my.oschina.net/primary) ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE=eth2TYPE=EthernetONBOOT=yesNM_CONTROLLED=yesBOOTPROTO=staticDNS1=114.114.114.114IPADDR=192.168.100.238NETMASK=255.255.255.0GATEWAY=192.168.100.254PREFIX=24DEFROUTE=yesIPV4_FAILURE_FATAL=yesIPV6INIT=noNAME="System eth2"UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03HWADDR=08:00:27:8e:51:f6LAST_CONNECT=1464664485USERCTL=no~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          ~                                                                                          "/etc/sysconfig/network-scripts/ifcfg-eth0" 18L, 341C

[root[@primary](https://my.oschina.net/primary) ~]# service network restart （或者/etc/init.d/network restart）Shutting down loopback interface:                          [  OK  ]Bringing up loopback interface:                               [  OK  ]Bringing up interface eth0:  Determining if ip address 192.168.100.238 is already in use for device eth2...                                                                                 [  OK  ][root[@primary](https://my.oschina.net/primary) ~]# ifconfigeth2      Link encap:Ethernet  HWaddr 08:00:27:8E:51:F6            inet addr:192.168.100.238  Bcast:192.168.100.255  Mask:255.255.255.0          inet6 addr: fe80::a00:27ff:fe8e:51f6/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:3378 errors:0 dropped:0 overruns:0 frame:0          TX packets:14 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:234683 (229.1 KiB)  TX bytes:776 (776.0 b)lo        Link encap:Local Loopback            inet addr:127.0.0.1  Mask:255.0.0.0          inet6 addr: ::1/128 Scope:Host          UP LOOPBACK RUNNING  MTU:16436  Metric:1          RX packets:15 errors:0 dropped:0 overruns:0 frame:0          TX packets:15 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:901 (901.0 b)  TX bytes:901 (901.0 b)