wget

rpm -ivh epel-release-latest-6.noarch.rpm

yum -y install iftop

报错：Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

是因为/etc/yum.repos.d/epel.repo配置文件中源地址没有生效

vim /etc/yum.repos.d/epel.repo

[epel]

name=Extra Packages for Enterprise Linux 6 - $basearch

#baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch

mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch

failovermethod=priority

enabled=1

gpgcheck=1

gpgkey=

修改成：

[epel]

..

baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch

#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch

...

保存退出后，清理源

yum clean all

yum -y install iftop    既可以成功安装。