yum -y install ftp
源出现错误时可以使用一下镜像文件直接安装
wget https://mirrors.tuna.tsinghua.edu.cn/centos-vault/6.9/os/x86_64/Packages/ftp-0.17-54.el6.x86_64.rpm
rpm -ivh ftp-0.17-54.el6.x86_64.rpm
https://mirrors.tuna.tsinghua.edu.cn/centos-vault/6.9/os/x86_64/Packages/
rpm -ivh gnutls-2.12.23-21.el6.x86_64.rpm
rpm -ivh lftp-4.0.9-14.el6.x86_64.rpm