下载地址:
​​​ https://centos.pkgs.org/6/centos-x86_64/telnet-0.17-48.el6.x86_64.rpm.html​​

查看一下安装包

yum list | grep telnet

安装:
yum install telnet.x86_64
或
rpm -ivh telnet-0.17-48.el6.x86_64.rpm