For SSH to be truly effective, using insecure connection protocols, such
as Telnet and FTP, 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:
To disable insecure connection methods to the system, use the command
line program chkconfig, the ncurses-based program
ntsysv, or the
Services Configuration Tool
(redhat-config-services) graphical application. All
of these tools require root level access.
For more information on runlevels and configuring services with
chkconfig, ntsysv, and the
Services Configuration Tool, refer to the chapter titled
Controlling Access to Services in the
Red Hat Enterprise Linux System Administration Guide.
