During installation of the system, a number of potential security risks are eliminated by disabling services that are not needed for the operation of the system. This is mainly achieved by:
Changing all system passwords from their default values (on operating system, database, and Web server accounts).
Verifying that no passwords are stored in clear text.
Turning off services provided via the Internet daemon (inetd), such as telnet, ftp, rlogin, rsh, rcp, finger, etc.
Preventing startup of other services that normally launch after a system boot, such as CDE (includes X11 server), uucp, NFS, sendmail, etc.
Restricting root account login to the console. To allow system maintenance and service, these utilities are installed and configured:
Secure Shell (OpenSSH) as replacement for telnet, ftp, and rlogin
rcp sudo, a utility that enables named users or users belonging to certain groups to execute a configurable and limited subset of commands that require root privilege (e.g., mounting/unmounting, reboot, addition/removal of packages, etc.)
This places the system in Safe Mode.
NOTE: A system operating in Safe Mode still might have vulnerabilities. The purpose of this mode is to balance a reasonable balance of security, functionality, and serviceability. If stricter security is needed, contact Customer Service.
If any of the disabled services are re-enabled, the system is considered to be operating in Unsafe Mode. Examples:
If a software upgrade is installed locally, an X11 server, such as openwin or CDE, might need to run (since some installers use a GUI).
When service must remotely access the system, but cannot use SSH, telnet and ftp must be re-enabled.
If a system has seriously malfunctioned and must be brought into Unsafe Mode, the details should be recorded (time, reason, by whom, and which services were re-enabled). When operation in Unsafe Mode is no longer valid, the system should be returned to Safe Mode (this action should also be recorded).
See these topics: