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.

To disable these services, type the following commands at a shell prompt:

~]# chkconfig telnet off
~]# chkconfig rsh off
~]# chkconfig rlogin off
~]# chkconfig vsftpd off

For more information on runlevels and configuring services in general, refer to Chapter 7, Controlling Access to Services.