CentOS 7 无法yum安装解决方法

问题描述：云主机可以ping通外网，iptables及安全组关闭，但是无法yum安装软件

服务器测试如下：

# wget -d http://mirrors.aliyun.com/repo/Centos-7.repo

DEBUG output created by Wget 1.14 on linux-gnu.

URI encoding = “UTF-8”

Converted file name 'Centos-7.repo' (UTF-8) -> 'Centos-7.repo' (UTF-8)

--2017-06-13 11:30:43-- http://mirrors.aliyun.com/repo/Centos-7.repo

正在连接 182.61.111.208:3128... Closed fd 3

失败：拒绝连接。

Releasing 0x000000000112fb60 (new refcount 0).

Deleting unused 0x000000000112fb60.

# yum install -y httpd

已加载插件：langpacks, versionlock

http://repo.bcm.baidubce.com/yum/repodata/repomd.xml: [Errno 14] curl#7 - "Failed connect to 182.61.111.208:3128; 拒绝连接"

正在尝试其它镜像。

# ping mirrors.aliyun.com -c 2

PING mirrors.aliyun.com (115.28.122.210) 56(84) bytes of data.

64 bytes from 115.28.122.210 (115.28.122.210): icmp_seq=1 ttl=48 time=34.8 ms

64 bytes from 115.28.122.210 (115.28.122.210): icmp_seq=2 ttl=48 time=34.5 ms

--- mirrors.aliyun.com ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 1001ms

rtt min/avg/max/mdev = 34.593/34.744/34.896/0.240 ms

# ping 182.61.111.208 -c 2PING 182.61.111.208 (182.61.111.208) 56(84) bytes of data.

64 bytes from 182.61.111.208: icmp_seq=1 ttl=48 time=42.3 ms

64 bytes from 182.61.111.208: icmp_seq=2 ttl=48 time=41.4 ms

--- 182.61.111.208 ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 1001ms

rtt min/avg/max/mdev = 41.436/41.882/42.328/0.446 ms

# telnet 182.61.111.208 3128Trying 182.61.111.208...

telnet: connect to address 182.61.111.208: Connection refused

排查思路：

1.检查防火墙设置，先关闭

# systemctl stop firewalld.service #停止firewall

# systemctl disable firewalld.service #禁止firewall开机启动

# systemctl restart iptables.service #重启防火墙使配置生效

# systemctl enable iptables.service #设置防火墙开机启动

2.telnet一个已知IP及端口，确定是服务端问题还是client问题

# curl -I http://180.76.148.122:80

curl: (7) Failed connect to 182.61.111.208:3128; 拒绝连接

发现拒绝的连接不是目标IP，被转发了，应该是使用了代理

3.查找可能的配置文件

# find /etc -type f | xargs grep -i '182.61.111.208'

/etc/profile:export http_proxy=http://182.61.111.208:3128/

4.编辑profile并重载

# vim /etc/profile

# tail -n 2 /etc/profile

#export LC_ALL=zh_CN.UTF-8

#export http_proxy=http://182.61.111.208:3128/

# source /etc/profile

5.重新ssh后下载查看

# wget http://mirrors.aliyun.com/repo/Centos-7.repo

--2017-06-13 12:01:47-- http://mirrors.aliyun.com/repo/Centos-7.repo

正在解析主机 mirrors.aliyun.com (mirrors.aliyun.com)... 112.124.140.210, 115.28.122.210

正在连接 mirrors.aliyun.com (mirrors.aliyun.com)|112.124.140.210|:80... 已连接。

已发出 HTTP 请求，正在等待回应... 200 OK

长度：2573 (2.5K) [application/octet-stream]

正在保存至: “Centos-7.repo”

100%[==================================================================================================================================================================>] 2,573 --.-K/s 用时 0s

2017-06-13 12:01:47 (99.1 MB/s) - 已保存 “Centos-7.repo” [2573/2573])

分享一个好用的yum源（aliyun）：

1）下载repo文件

wget http://mirrors.aliyun.com/repo/Centos-7.repo

2）备份并替换系统的repo文件

cp Centos-7.repo /etc/yum.repos.d/

cd /etc/yum.repos.d/

mv CentOS-Base.repo CentOS-Base.repo.bak

mv Centos-7.repo CentOS-Base.repo

3）执行yum源更新命令

yum clean all

yum makecache

yum update

配置完毕。

CentOS 7 无法yum安装解决方法

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