原文地址：https://www.biaodianfu.com/centos-7-network-problem.html

CentOS 发布已经很久了，由于本次版本变动比较大，特别是systemd的加入，所以先前一直使用的是centos 6.7版本。今天抽空在虚拟机上安装了CentOS 7，在安装完成后使用 yum update -y 进行系统更新，返回了错误信息：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Loaded plugins : fastestmirror , priorities , security
Setting up Update Process
Determining fastest mirrors
Could not retrieve mirrorlist http : //mirrorlist.centos.org/?release=6&arch=x86_64&repo=os&infra=stock error was
14 : PYCURL ERROR 6 - "Couldn't resolve host 'mirrorlist.centos.org'"
Error : Cannot find a valid baseurl for repo : base
 
One of the configured repositories failed ( Unknown ) ,    and yum doesn 't
have enough cached data to continue. At this point the only  safe
thing yum can do is fail. There are a few ways to work "fix" this:
 
      1. Contact the upstream for the repository and get them to fix the problem.
 
      2. Reconfigure the baseurl/etc. for the repository, to point to a working
         upstream. This is most often useful if you are using a newer
         distribution release than is supported by the repository (and the
         packages for the previous distribution release still work).
 
      3. Disable the repository, so yum won' t use it by default . Yum will then
         just ignore the repository until you permanently enable it again or use
         -- enablerepo for temporary usage :
 
             yum - config - manager -- disable < repoid >
 
       4. Configure the failing repository to be skipped , if it is unavailable .
         Note that yum will try to contact the repo . when it runs most commands ,
         so will have to try and fail each time ( and thus . yum will be be much
         slower ) . If it is a very temporary problem though , this is often a nice
         compromise :
 
             yum - config - manager -- save -- setopt = < repoid > . skip_if_unavailable = true
 
Cannot find a valid baseurl for repo : base / 7 / x86_64 `

初步判断是网络问题，使用ifconfig查看下网络信息，但是发现：

1
- bash : ifconfig : command not found

ifconfig也不能使用了，Google了下发现ifconfig命令已经被ip命令给取代了。具体ip命令的使用方法如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
ip    [选项 ]   操作对象 { link | addr | route . . . }
 
# ip link show                # 显示网络接口信息
# ip link set eth0 upi           # 开启网卡
# ip link set eth0 down          # 关闭网卡
# ip link set eth0 promisc on      # 开启网卡的混合模式
# ip link set eth0 promisc offi     # 关闭网卡的混个模式
# ip link set eth0 txqueuelen 1200   # 设置网卡队列长度
# ip link set eth0 mtu 1400        # 设置网卡最大传输单元
# ip addr show                # 显示网卡IP信息
# ip addr add 192.168.0.1/24 dev eth0 # 设置eth0网卡IP地址192.168.0.1
# ip addr del 192.168.0.1/24 dev eth0 # 删除eth0网卡IP地址
 
# ip route list                 # 查看路由信息
# ip route add 192.168.4.0/24  via  192.168.0.254 dev eth0 # 设置192.168.4.0网段的网关为192.168.0.254,数据走eth0接口
# ip route add default via  192.168.0.254  dev eth0    # 设置默认网关为192.168.0.254
# ip route del 192.168.4.0/24      # 删除192.168.4.0网段的网关
# ip route del default          # 删除默认路由

按照方法，输入了 ip addr ，发现网卡eno16777736并没有IP地址。既然没有ip地址，那直接去/etc/sysconfig/network-scripts目录中看一下的网卡ip信息的配置文件。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
[ root @ localhost ~ ] # cd /etc/sysconfig/network-scripts
[ root @ localhost network - scripts ] # ll
total 196
- rw - r -- r -- . 1 root root    288 Aug 18 22 : 36 ifcfg - eno16777736
- rw - r -- r -- . 1 root root    254 Sep 16    2015 ifcfg - lo
lrwxrwxrwx . 1 root root      24 Aug 18 22 : 48 ifdown -> . . / . . / . . / usr / sbin / ifdown
- rwxr - xr - x . 1 root root    627 Sep 16    2015 ifdown - bnep
- rwxr - xr - x . 1 root root    5817 Sep 16    2015 ifdown - eth
- rwxr - xr - x . 1 root root    781 Sep 16    2015 ifdown - ippp
- rwxr - xr - x . 1 root root    4201 Sep 16    2015 ifdown - ipv6
lrwxrwxrwx . 1 root root      11 Aug 18 22 : 48 ifdown - isdn -> ifdown - ippp
- rwxr - xr - x . 1 root root    1642 Sep 16    2015 ifdown - post
- rwxr - xr - x . 1 root root    1068 Sep 16    2015 ifdown - ppp
- rwxr - xr - x . 1 root root    837 Sep 16    2015 ifdown - routes
- rwxr - xr - x . 1 root root    1444 Sep 16    2015 ifdown - sit
- rwxr - xr - x . 1 root root    1462 Sep 16    2015 ifdown - tunnel
lrwxrwxrwx . 1 root root      22 Aug 18 22 : 48 ifup -> . . / . . / . . / usr / sbin / ifup
- rwxr - xr - x . 1 root root 12631 Sep 16    2015 ifup - aliases
- rwxr - xr - x . 1 root root    859 Sep 16    2015 ifup - bnep
- rwxr - xr - x . 1 root root 11721 Sep 16    2015 ifup - eth
- rwxr - xr - x . 1 root root 12039 Sep 16    2015 ifup - ippp
- rwxr - xr - x . 1 root root 10430 Sep 16    2015 ifup - ipv6
lrwxrwxrwx . 1 root root      9 Aug 18 22 : 48 ifup - isdn -> ifup - ippp
- rwxr - xr - x . 1 root root    642 Sep 16    2015 ifup - plip
- rwxr - xr - x . 1 root root    1043 Sep 16    2015 ifup - plusb
- rwxr - xr - x . 1 root root    2609 Sep 16    2015 ifup - post
- rwxr - xr - x . 1 root root    4154 Sep 16    2015 ifup - ppp
- rwxr - xr - x . 1 root root    1925 Sep 16    2015 ifup - routes
- rwxr - xr - x . 1 root root    3263 Sep 16    2015 ifup - sit
- rwxr - xr - x . 1 root root    2682 Sep 16    2015 ifup - tunnel
- rwxr - xr - x . 1 root root    1740 Sep 16    2015 ifup - wireless
- rwxr - xr - x . 1 root root    4623 Sep 16    2015 init . ipv6 - global
- rw - r -- r -- . 1 root root 15376 Aug    3 00 : 15 network - functions
- rw - r -- r -- . 1 root root 26134 Sep 16    2015 network - functions - ipv6

可以看到network-scripts目录下面的ifcfg-eth0变成了ifcfg-eno16777736。使用cat命令查看下ifcfg-eno16777736的内容：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
[ root @ localhost network - scripts ] # cat ifcfg-eno16777736
TYPE = Ethernet
BOOTPROTO = dhcp
DEFROUTE = yes
PEERDNS = yes
PEERROUTES = yes
IPV4_FAILURE_FATAL = no
IPV6INIT = yes
IPV6_AUTOCONF = yes
IPV6_DEFROUTE = yes
IPV6_PEERDNS = yes
IPV6_PEERROUTES = yes
IPV6_FAILURE_FATAL = no
NAME = eno16777736
UUID = ba6856dc - abf2 - 45e4 - 91d6 - 581eddab8d61
DEVICE = eno16777736
ONBOOT = no

从上面的配置中有看到虽然BOOTPROTO=dhcp，但是ONBOOT=no，这里用vi将ONBOOT=no改成ONBOOT=yes，然后重新系统或者重启网络即可：

1
systemctl restart network . service


原文地址：https://www.biaodianfu.com/centos-7-network-problem.html

Logo
华为开发者空间

华为开发者空间，是为全球开发者打造的专属开发空间，汇聚了华为优质开发资源及工具，致力于让每一位开发者拥有一台云主机，基于华为根生态开发、创新。

更多推荐

cover

一文解读GaussDB(DWS)监控运维诊断优化能力

avatar 华为开发者空间
cover

GaussDB技术解读——GaussDB架构介绍（四）

avatar 华为开发者空间
cover

华为云数据仓库专业级开发者认证重磅发布

avatar 华为开发者空间