1. Check whether telnet has been installed:

rpm -qa telnet

2. There is an output indicating that it has been installed. If there is no output, it is not installed. Use yum install telnet to install

3. Check whether telnet-server has been installed:

rpm -qa telnet-server

If there is output, it is installed. If there is no output, it is not installed. Use yum install telnet-server to install

4. If the telnet-server installation operation has been performed and it has been successfully installed, since the telnet service is guarded by xinetd, we need to restart xinetd

service xinetd restart

5. If an error is reported: Redirecting to /bin/systemctl restart xinetd.service , see https://programmerah.com/install-and-start-the-tftp-server-server-and-possible-solutions-to-redirecting-to-bin-systemctl-restart-xinetd-service-problems-27961/

6. If xinetd is started successfully, you can check the running status of xinetd

netstat -tnlp