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8.2.3. Requiring SSH for Remote Connections

For SSH to be truly effective, using insecure connection protocols should be prohibited. Otherwise, a user's password may be protected using SSH for one session, only to be captured later while logging in using Telnet. Some services to disable include telnet, rsh, rlogin, and vsftpd.
These services are not installed by default in Fedora. If required, to make sure these services are not running, type the following commands at a shell prompt:
systemctl stop telnet.service
systemctl stop rsh.service
systemctl stop rlogin.service
systemctl stop vsftpd.service
To disable running these services at startup, type:
systemctl disable telnet.service
systemctl disable rsh.service
systemctl disable rlogin.service
systemctl disable vsftpd.service
See Chapter 7, Services and Daemons for more information on how to configure services in Fedora.