Unusual or hidden files
It is important to not forget to look everywhere on the system for unusual or hidden files (files that start with a period and are normally not shown by the “Is” command), as these can be used to hide tools and information (password cracking programs, password files from other systems, etc.). A common technique on UNIX systems is to put a hidden directory or file in a user’s account with an unusual name, something like ‘…’ or’..’ (dot dot space) or ‘..AG’ (dot dot control-G). The “find” program can be used to look for hidden files. (Далее…)
The kernel tunable parameters
With the new version of Red Hat Linux 6.2 all kernel parameters available under the 7proc/sys” subdirectory of Linux can be configured at runtime. You can now use the new “/etc/sysctl.conf file under Red Hat Linux 6.2 to modify and set kernel parameters at runtime. The “sysctl.conf” file is read and loaded each time the system reboots. All settings are now stored in the “/etc/sysctl.conf file. All modifications to 7proc/sys” should be made through “/etc/sysctl.conf, because they are better for control, and are executed before “rc.local” or any other “users” scripts. Below, we show you the networking security options that you must configure on your server for Red Hat Linux version 6.1 and 6.2. (Далее…)
Fix the permissions under “/etc/rc.d/init.d” directory for script files
Fix the permissions of the script files that are responsible for starting and stopping all your normal processes that need to run at boot time.
[root@deep /]# chmod -R 700 /etc/rc.d/init.d/* (Далее…)
Disable the Control-Alt-Delete keyboard shutdown command
Commenting out the line (with a “#”) listed below in your 7etc/inittab” file will disable the possibility of using the Control-Alt-Delete command to shutdown your computer. This is pretty important if you don’t have the best physical security on the box. (Далее…)
Shell logging
To make it easy for you to repeat long commands, the bash shell stores up to 500 old commands in the “~/.bash_history” file (where”-/” is your home directory). Each user that has an account on the system will have this file “.bashjiistory” in their home directory. Reducing the number of old commands the “.bashjiistory” files can hold may protect users on the server who enter by mistake their password on the screen in plain text and have their password stored for a long time in the “.bash_history” file. (Далее…)