For SSH to be truly effective in protecting your network connections,
you must stop using all insecure connection protocols, such as
telnet and rsh. Otherwise, a
user's password may be protected using ssh for one
log in only to be captured when they log in again using
telnet.
To disable insecure connection methods to your system, use the
command line program chkconfig, the ncurses-based
program ntsysv, or the graphical application
serviceconf. All of these tools require root
access.
Some services to disable include:
telnet
rsh
ftp
rlogin
wu-ftpd
vsftpd
For more information on runlevels and configuring services with
chkconfig, ntsysv, and
serviceconf, refer to the chapter titled
Controlling Access to Services in the
Official Red Hat Linux Customization Guide.
