device does not seem;RTNETLINK answers:File exists

前言：Centos 7服務器出現網絡異常的問題
排查步驟：
1.確認是否有IP地址
2.重啓網卡是否成功
3.是否有衝突的網絡管理工具（network&NetworkManger）
4.檢查網卡的配置文件是否正常
Warning：主要看日誌，默認Log存放位置（/var/log/messages)
（1）檢測是否有IP地址
(這裏就不上圖了，能夠看到網卡信息，可是沒有IP地址)
咱們看一下日誌

Apr  8 10:35:20 localhost network: Bringing up interface eth0:  ERROR     : [/etc/sysconfig/network-scripts/ifup-eth] Device  has different MAC address than expected, ignoring.
Apr  8 10:35:20 localhost /etc/sysconfig/network-scripts/ifup-eth: Device  has different MAC address than expected, ignoring.
Apr  8 10:35:20 localhost network: [FAILED]
Apr  8 10:35:20 localhost systemd: network.service: control process exited, code=exited status=1
Apr  8 10:35:20 localhost systemd: Failed to start LSB: Bring up/down networking.
Apr  8 10:35:20 localhost systemd: Unit network.service entered failed state.
Apr  8 10:35:20 localhost systemd: network.service failed.

這裏明顯說明MAC地址問題咱們就看一下MAC地址是否正確

[root@localhost ~]# grep HAW /etc/sysconfig/network-scripts/ifcfg-eth0 
HAWDDR="打碼不給你看"

而後確認一下eth0網卡的MAC地址是否正確

[root@localhost ~]# cat /sys/class/net/eth0/address 
打碼打碼

如今確認MAC地址不一致，咱們修改網卡配置文件

[root@localhost ~]sed -i 's'/原配置文件的MAC/如今配置文件的MAC/g' /etc/sysconfig/network-scripts/ifcfg-eth0

再次重啓網卡

[root@localhost ~]# systemctl restart network

不出意外又報錯了，咱們再看一下日誌信息

Apr  8 10:43:47 localhost /etc/sysconfig/network-scripts/ifup-eth: Device  does not seem to be present, delaying initialization.
Apr  8 10:43:47 localhost network: [FAILED]
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists
Apr  8 10:43:47 localhost network: RTNETLINK answers: File exists

此次的報錯不同了，告訴咱們找不到文件（這種類型的報錯範圍廣，不容易排查，咱們從一下幾點排查）
1.首先排查配置文件是否指定網卡名稱
對象：文件名
網卡配置：NAME、DEVICE
2.檢查70-persistent-net.rules自定義網卡信息配置文件
3.網卡信息是否刷新
(1)檢查配置文件名稱

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 
# Generated by dracut initrd
NAME="eth0"
HWADDR="打碼"
ONBOOT=yes
NETBOOT=yes
UUID="打碼"
IPV6INIT=yes
BOOTPROTO=dhcp
TYPE=Ethernet

這裏缺乏DEVICE名稱咱們加上

[root@localhost ~]# sed -i '3a/DEVICE=eth0' /etc/sysconfig/network-scripts/ifcfg-eth0

重啓服務嘗試

[root@localhost ~]# systemctl restart network

服務正常了
（2）檢查70-persistent-net.rules自定義網卡信息配置文件

[root@localhost ~]# cat /etc/udev/rules.d/70-persistent-net.rules

若是沒有這個文件這一步能夠跳過，有的話比對信息
（3）刷新網卡

[root@localhost ~]# ip addr flush dev eth0

通常這些作完就能夠排除網卡配置問題若是還有問題請檢查route、dns、到DHCP服務器是否正常、若是是虛擬機的話查看虛擬機網卡配置是否正常等