Chapter 9. SSH Protocol

135

9.6. Require SSH for Remote Connections

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 he logs in again using

telnet

.

To disable insecure connection methods to your system, use the command line program

chkcon 

fig

, the ncurses based program ntsysv, or the graphical application Services Configuration Tool

(

redhat config services

). 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 Services

Configuration Tool, refer to the chapter titled Controlling Access to Services in the Official Red Hat

Linux Customization Guide.