1.查看當前的系統版本和openssh，openssl版本 2.安裝telnet rpm -ivh xinetd-2.3.15-14.el7.x86_64.rpm rpm -ivh telnet-0.17-66.el7.x86_64.rpm rpm -ivh telnet-server-0.17-66.el7.x86_64.rpm systemctl start telnet.socket s
