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  1. 2014.12.12 How to Disable Your Bash_History or Log Users
2014.12.12 19:32

How to Disable Your Bash_History or Log Users

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   ██                                                                       ██
  █▌      -   DISABLING BASH_HISTORY AND/OR LOGGING ALL USER'S CMDS   -      █▌
 █▌                                                                           █▌
 █                                                                            ▐▌
 █ Once you have logged out of your shell by default bash will store the last ▐▌
 █ 500 previous cmds (commands), and/or 500 lines, you executed to your       ▐▌
 █ .bash_history file for easy recall on future sessions (Ctrl+R or ! or !!). ▐▌
 █ Even passwords that were entered as plain text, such as:                   ▐▌
 █ mysqladmin -u root password 'new-password'                                 ▐▌
 █ If you take a look at hack logs, many have "cat .bash_history". HERE is a  ▐▌
 █ an infamous example, search for: cat .bash_history                         ▐▌
 █                                                                            ▐▌
 █ I've listed a number of different methods to disable it, limit it, or stop ▐▌
 █ users from altering their own .bash_history for auditing needs. Depending  ▐▌
 █ on your own needs select a method/s.                                       ▐▌
 █                                                                            ▐▌
 █ QUICK METHOD:                                                              ▐▌
 █ TO VIEW YOUR .BASH_HISTORY:                                                ▐▌
 █ SOME COMMON BASH VARIABLES:                                                ▐▌
 █ VARIABLE NOTES:                                                            ▐▌
 █ DISABLE .BASH_HISTORY - INCLUDING CURRENT SESSION'S KEYSTROKES:            ▐▌
 █ DISABLE .BASH_HISTORY - WHILE RETAINING CURRENT SESSION'S KEYSTROKE:       ▐▌
 █ TEMPORARILY DISABLE YOUR .BASH_HISTORY:                                    ▐▌
 █ LIMIT (not disable) .BASH_HISTORY FOR ALL USERS:                           ▐▌
 █ PREVENT USERS MODIFYING THEIR .BASH_HISTORY:                               ▐▌
 █                                                                            ▐▌
 █ QUICK METHOD:                                                              ▐▌
 █ `````````````                                                              ▐▌
 █ Quick method to completely disable your own .bash_history, without reading ▐▌
 █ any further:                                                               ▐▌
 █ Remove the file:                                                           ▐▌
 █ rm ~/.bash_history -rf                                                     ▐▌
 █ Clear your current history stored in RAM:                                  ▐▌
 █ history -c                                                                 ▐▌
 █ Change your settings:                                                      ▐▌
 █ export HISTFILESIZE=0                                                      ▐▌
 █ export HISTSIZE=0                                                          ▐▌
 █ unset HISTFILE                                                             ▐▌
 █ Logout, login, done.                                                       ▐▌
 █                                                                            ▐▌
 █ Or even faster method to send .bash_history to a black hole:               ▐▌
 █ rm ~/.bash_history                                                         ▐▌
 █ ln /dev/null ~/.bash_history -sf                                           ▐▌
 █ Logout, login, done.                                                       ▐▌
 █                                                                            ▐▌
 █ TO VIEW YOUR .BASH_HISTORY:                                                ▐▌
 █ ```````````````````````````                                                ▐▌
 █ history                                                                    ▐▌
 █ or                                                                         ▐▌
 █ ls -al .bash_history                                                       ▐▌
 █ cat ~/.bash_history                                                        ▐▌
 █ The number of cmds that history will show (cmd number on left column)      ▐▌
 █ might be larger than the default 500 as it includes your current session's ▐▌
 █ cmds and what is in .bash_history.                                         ▐▌
 █ To view your top 10 bash cmds in your present history:                     ▐▌
 █ history | awk '{print $2}' | awk 'BEGIN {FS="|"}{print $1}' | sort | uniq -c | sort -n | tail | sort -nr
 █ You can re-execute any cmd on the list by entering the item number         ▐▌
 █ preceded with !                                                            ▐▌
 █ For example if on the list is the cmd above as 502, to re-execute it:      ▐▌
 █ !502                                                                       ▐▌
 █ Or to re-execute the previous cmd:                                         ▐▌
 █ !!                                                                         ▐▌
 █                                                                            ▐▌
 █ SOME COMMON BASH VARIABLES:                                                ▐▌
 █ ```````````````````````````                                                ▐▌
 █ Can skip this section; not needed to read/do:                              ▐▌
 █ Here is a list of some of the variables, with a brief description. Don't   ▐▌
 █ worry if these don't make sense now, you'll see how to use them below.     ▐▌
 █ Bash man page is HERE or in your shell prompt: man bash                    ▐▌
 █                                                                            ▐▌
 █ HISTFILE                                                                   ▐▌
 █   Set the name/path of bash history. Default is ~/.bash_history. If        ▐▌
 █   'unset' bash history is not saved after exiting.                         ▐▌
 █ HISTFILESIZE                                                               ▐▌
 █   Set the maximum number of lines to be saved in .bash_history             ▐▌
 █ HISTSIZE                                                                   ▐▌
 █   Set the number of commands to remember/store in .bash_history            ▐▌
 █ HISTTIMEFORMAT                                                             ▐▌
 █   Time stamp the commands. Example: export HISTTIMEFORMAT='%Y-%m-%d %H:%M' ▐▌
 █ HISTCONTROL                                                                ▐▌
 █   Here you can have a colon separated list of 'values' controlling what is ▐▌
 █   stored in .bash_history. Here are a few of them:                         ▐▌
 █   ignorespace - cmds that begin with a space will not be saved.            ▐▌
 █   ignoredups - cmds matching previous entries will not be saved.           ▐▌
 █   ignoreboth -  ignoredups and ignorespace combined.                       ▐▌
 █   erasedups - erases previous duplicate cmds in history before the new cmd ▐▌
 █   is saved. I prefer using this line over ignoredups with HISTTIMEFORMAT   ▐▌
 █   as the latest occurance of the cmd is saved.                             ▐▌
 █   Here is an example using the above:                                      ▐▌
 █   export HISTCONTROL=ignorespace:erasedups                                 ▐▌
 █ HISTIGNORE                                                                 ▐▌
 █   Here you can have a colon separated list of 'patterns' controlling what  ▐▌
 █   is stored in .bash_history.                                              ▐▌
 █   "[ ]*" - cmds that begin with a space will not be saved.                 ▐▌
 █   "&" - cmds matching previous entries will not be saved.                  ▐▌
 █   Here is an example that will ignore duplicate cmds, cmds that begin with ▐▌
 █   a space, and the exit cmd:                                               ▐▌
 █   export HISTIGNORE='&:[ ]*:exit'                                          ▐▌
 █ PROMPT_COMMAND                                                             ▐▌
 █   To execute a set command prior to each of your primary commands. For     ▐▌
 █   example if open multiple shell sessions and do not want each one         ▐▌
 █   overwriting your .bash_history on exit you could do this:                ▐▌
 █   export PROMPT_COMMAND=history -a; history -n                             ▐▌
 █   Or to save, append and reload history after each cmd executes:           ▐▌
 █   export PROMPT_COMMAND='history -a; history -r; $PROMPT_COMMAND'          ▐▌
 █   shopt -s histappend                                                      ▐▌
 █ TMOUT                                                                      ▐▌
 █   The number of seconds until the shell session automatically terminates   ▐▌
 █   if it doesn't receive input. A 0 value means the shell will not          ▐▌
 █   automatically terminate.                                                 ▐▌
 █                                                                            ▐▌
 █ VARIABLE NOTES:                                                            ▐▌
 █ ```````````````                                                            ▐▌
 █ 1) To activate the changes to a user's variables, the user will need to    ▐▌
 █ logout then back in (or open a new session or run the altered file).       ▐▌
 █                                                                            ▐▌
 █ 2) To list your own environment variables:                                 ▐▌
 █ env                                                                        ▐▌
 █                                                                            ▐▌
 █ If for example you have previously entered the cmd:                        ▐▌
 █ export HISTCONTROL=ignorespace                                             ▐▌
 █ You'll see 'HISTCONTROL=ignorespace' in the output of env.                 ▐▌
 █                                                                            ▐▌
 █ To view a specific variable, precede that variable with: echo $            ▐▌
 █ If there is no reply, it hasn't been manually set, and is at the default.  ▐▌
 █ For example:                                                               ▐▌
 █ echo $HISTFILESIZE                                                         ▐▌
 █ echo $HISTSIZE                                                             ▐▌
 █ echo $TMOUT                                                                ▐▌
 █                                                                            ▐▌
 █ 3) To remove a variable that you have set use 'unset'.                     ▐▌
 █ For example if you have done:                                              ▐▌
 █ export HISTSIZE=500                                                        ▐▌
 █ then remove that with:                                                     ▐▌
 █ unset HISTSIZE                                                             ▐▌
 █                                                                            ▐▌
 █ 4) Keep in mind that if you change a user's bash environment variable,     ▐▌
 █ they can change it back if the correct permissions are not set. I'll go    ▐▌
 █ over that in the section 'PREVENT USERS MODIFYING THEIR .BASH_HISTORY'.    ▐▌
 █                                                                            ▐▌
 █ 5) You might need to replace the double quotes " with single quotes ' in   ▐▌
 █ the variables below if you receive an error.                               ▐▌
 █                                                                            ▐▌
 █                                                                            ▐▌
 █ DISABLE .BASH_HISTORY - INCLUDING CURRENT SESSION'S KEYSTROKES:            ▐▌
 █ ```````````````````````````````````````````````````````````````            ▐▌
 █ With this method you will not be able to recall previous cmds (Ctrl+r).    ▐▌
 █                                                                            ▐▌
 █ FOR YOURSELF:                                                              ▐▌
 █ Clear your current history:                                                ▐▌
 █ history -c                                                                 ▐▌
 █ Remove the file:                                                           ▐▌
 █ rm ~/.bash_history -rf                                                     ▐▌
 █ Change your settings:                                                      ▐▌
 █ export HISTFILESIZE=0                                                      ▐▌
 █ export HISTSIZE=0                                                          ▐▌
 █ unset HISTFILE                                                             ▐▌
 █                                                                            ▐▌
 █ (or you could add those settings to your ~/.bash_profile)                  ▐▌
 █                                                                            ▐▌
 █ FOR A SPECIFIED USER (replace 'user' with user's name):                    ▐▌
 █ su                                                                         ▐▌
 █ Clear their history:                                                       ▐▌
 █ history -c /home/user/.bash_history                                        ▐▌
 █ Remove the file:                                                           ▐▌
 █ rm /home/user/.bash_history -rf                                            ▐▌
 █ Change their settings:                                                     ▐▌
 █ echo "export HISTFILESIZE=0" >> /home/user/.bash_profile                   ▐▌
 █ echo "export HISTSIZE=0" >> /home/user/.bash_profile                       ▐▌
 █ echo "unset HISTFILE" >> /home/user/.bash_profile                          ▐▌
 █                                                                            ▐▌
 █ FOR ALL USERS:                                                             ▐▌
 █ su                                                                         ▐▌
 █ pico /etc/profile                                                          ▐▌
 █ Add these lines at the end of the file:                                    ▐▌
 █ export HISTFILESIZE=0                                                      ▐▌
 █ export HISTSIZE=0                                                          ▐▌
 █ unset HISTFILE                                                             ▐▌
 █ ln /dev/null ~/.bash_history -sf                                           ▐▌
 █                                                                            ▐▌
 █ You'll need to remove all users .bash_history files. Find them first to be ▐▌
 █ sure these are the files you want to remove:                               ▐▌
 █ find /home -type f -name .bash_history                                     ▐▌
 █                                                                            ▐▌
 █ If your output above is correct, then to remove all of those files:        ▐▌
 █ find /home -type f -name .bash_history \                                   ▐▌
 █ -exec rm -f {} \;                                                          ▐▌
 █                                                                            ▐▌
 █ Or:                                                                        ▐▌
 █ pico /etc/bash.bashrc                                                      ▐▌
 █ Add these lines at the end:                                                ▐▌
 █ export HISTFILE=                                                           ▐▌
 █ ln /dev/null ~/.bash_history -sf                                           ▐▌
 █                                                                            ▐▌
 █ Or you could add these lines instead:                                      ▐▌
 █ export HISTSIZE=0                                                          ▐▌
 █ ln /dev/null ~/.bash_history -sf                                           ▐▌
 █                                                                            ▐▌
 █ Or you could:                                                              ▐▌
 █ echo "unset HISTFILE" >> /etc/profile                                      ▐▌
 █                                                                            ▐▌
 █ As you can see there are a number of methods that can be applied to all    ▐▌
 █ users including root.                                                      ▐▌
 █                                                                            ▐▌
 █ FOR ROOT:                                                                  ▐▌
 █ su                                                                         ▐▌
 █ Clear root history:                                                        ▐▌
 █ history -c /root/.bash_history                                             ▐▌
 █ Or:                                                                        ▐▌
 █ cat /dev/null > /root/.bash_history                                        ▐▌
 █ Send bash history to a black hole:                                         ▐▌
 █ ln /dev/null /root/.bash_history -sf                                       ▐▌
 █ rm /root/.bash_history -f                                                  ▐▌
 █                                                                            ▐▌
 █ Or you can add the settings:                                               ▐▌
 █ pico /root/.bash_profile                                                   ▐▌
 █ If that file doesn't exist then:                                           ▐▌
 █ pico /root/.bashrc                                                         ▐▌
 █ or                                                                         ▐▌
 █ pico /root/.profile                                                        ▐▌
 █ Paste these lines at the bottom:                                           ▐▌
 █ export HISTFILESIZE=0                                                      ▐▌
 █ export HISTSIZE=0                                                          ▐▌
 █ unset HISTFILE                                                             ▐▌
 █                                                                            ▐▌
 █ If you choose to do this for root you should consider a logging program    ▐▌
 █ to monitor root actions and if possible have the logs sent live to another ▐▌
 █ server.                                                                    ▐▌
 █                                                                            ▐▌
 █ DISABLE .BASH_HISTORY - WHILE RETAINING CURRENT SESSION'S KEYSTROKE:       ▐▌
 █ ````````````````````````````````````````````````````````````````````       ▐▌
 █ To be able to recall the current session's recent cmds (Ctrl+r) for        ▐▌
 █ example to 30 lines, in all the statements above for 'export HISTSIZE=0'   ▐▌
 █ change to:                                                                 ▐▌
 █ export HISTSIZE=30                                                         ▐▌
 █                                                                            ▐▌
 █ Or you could:                                                              ▐▌
 █ export HISTFILE=/dev/null                                                  ▐▌
 █                                                                            ▐▌
 █ Or you could:                                                              ▐▌
 █ pico ~/.bashrc                                                             ▐▌
 █ Add this line:                                                             ▐▌
 █ HISTFILE=/dev/null                                                         ▐▌
 █                                                                            ▐▌
 █ TEMPORARILY DISABLE YOUR .BASH_HISTORY:                                    ▐▌
 █ ```````````````````````````````````````                                    ▐▌
 █ If you want to temporarily disable the logging of your commands, first:    ▐▌
 █ unset HISTFILE                                                             ▐▌
 █ Or you could:                                                              ▐▌
 █ export HISTFILE=/dev/null                                                  ▐▌
 █ Run your cmds, then reset it:                                              ▐▌
 █ export HISTFILE=~/.bash_history                                            ▐▌
 █ Or if you didn't care to save the .previous .bash_history and kill         ▐▌
 █ everything without a wait, after you are finished (not recommended) log    ▐▌
 █ out with this cmd:                                                         ▐▌
 █ rm ~/.bash_history -f && kill -9 $$                                        ▐▌
 █                                                                            ▐▌
 █ LIMIT (not disable) .BASH_HISTORY FOR ALL USERS:                           ▐▌
 █ ````````````````````````````````````````````````                           ▐▌
 █ pico /etc/profile                                                          ▐▌
 █ Add these lines at the end, or adjust if already there to limit users to   ▐▌
 █ 20 previous cmds:                                                          ▐▌
 █ HISTFILESIZE=30                                                            ▐▌
 █ HISTSIZE=30                                                                ▐▌
 █                                                                            ▐▌
 █ PREVENT USERS MODIFYING THEIR .BASH_HISTORY:                               ▐▌
 █ ````````````````````````````````````````````                               ▐▌
 █ Keep in mind that the methods below for bash are not impossible to bypass, ▐▌
 █ as clever users can find ways around this such as few methods that I have  ▐▌
 █ read about and listed below.                                               ▐▌
 █                                                                            ▐▌
 █ 1) To not allow users (or even root) to modify, move, or delete their      ▐▌
 █ .bash_history you need to set an attribute to append only (replace user    ▐▌
 █ with the user's name):                                                     ▐▌
 █ su                                                                         ▐▌
 █ chattr +a /home/user/.bash_history                                         ▐▌
 █ FreeBSD it would be: sappnd /home/user/.bash_history                       ▐▌
 █                                                                            ▐▌
 █ You should also set append only to all the other bash configuration files. ▐▌
 █ When users logs in, bash reads first from /etc/profile, then the first     ▐▌
 █ three in this order:                                                       ▐▌
 █ chattr +a /home/user/.bash_profile                                         ▐▌
 █ chattr +a /home/user/.bash_login                                           ▐▌
 █ chattr +a /home/user/.profile                                              ▐▌
 █ chattr +a /home/user/.bashrc                                               ▐▌
 █ chattr +a /home/user/.bash_logout                                          ▐▌
 █                                                                            ▐▌
 █ .bashrc is read when                                                       ▐▌
 █ A. another interactive shell is started, for example by entering: bash and ▐▌
 █ B. When it is referred to from the other .bash files containing .bashrc in ▐▌
 █ their body - so that means in every case.                                  ▐▌
 █                                                                            ▐▌
 █ Here is an example to change the perms to +a on all the files listed       ▐▌
 █ above, in all the users /home directory, in mass:                          ▐▌
 █ You might want to search files first to know you have all/only the correct ▐▌
 █ files:                                                                     ▐▌
 █ find /home -type f -name .bash\*                                           ▐▌
 █ find /home -type f -name .profile                                          ▐▌
 █                                                                            ▐▌
 █ Then to change to the perms:                                               ▐▌
 █ find /home -type f -name .bash\* \                                         ▐▌
 █ -exec chattr +a {} \;                                                      ▐▌
 █ find /home -type f -name .profile \                                        ▐▌
 █ -exec chattr +a {} \;                                                      ▐▌
 █                                                                            ▐▌
 █ Even for root to edit files that are set to chattr +a that attribute must  ▐▌
 █ be removed first.                                                          ▐▌
 █ To view chattr attributes on the file:                                     ▐▌
 █ lsattr .bash_history                                                       ▐▌
 █ Output would be: -----a-------------                                       ▐▌
 █ To remove an 'a' attribute:                                                ▐▌
 █ chattr -a .bash_history                                                    ▐▌
 █ Or if lsattr replied with an 'i' then -i. The i attribute is immutable- no ▐▌
 █ append ability.                                                            ▐▌
 █ To know more about chattr view HERE, or man chattr                         ▐▌
 █                                                                            ▐▌
 █ 2) Then you need to set the variables so that each cmd a user executes is  ▐▌
 █ logged immediately, and variables are set to read only so that users can't ▐▌
 █ change them such as the size, location, and log all cmds. To do this:      ▐▌
 █ pico /etc/profile                                                          ▐▌
 █ Add the following lines to the bottom of the file:                         ▐▌
if [ "$BASH" ]; then
	PROMPT_COMMAND="history -a;$PROMPT_COMMAND";
	readonly PROMPT_COMMAND
	readonly HISTSIZE
	readonly HISTFILE
    readonly HISTFILESIZE
    readonly HISTCMD
	readonly HOME
	readonly HISTIGNORE
	readonly HISTCONTROL
fi
 █                                                                            ▐▌
 █ 3) Disable access to other shells programs on the system so the users must ▐▌
 █ use bash. Some of the more common ones are csh, tcsh and ksh.              ▐▌
 █ To find location of program; which [program], for example:                 ▐▌
 █ which csh                                                                  ▐▌
 █ which tcsh                                                                 ▐▌
 █                                                                            ▐▌
 █ chmod 750 /bin/csh                                                         ▐▌
 █ chmod 750 /usr/bin/tcsh                                                    ▐▌
 █                                                                            ▐▌
 █ On standard Debian install there is csh (/bin/csh) and tcsh                ▐▌
 █ (/usr/bin/tcsh). Find out what other shells are installed on your own      ▐▌
 █ system.                                                                    ▐▌
 █                                                                            ▐▌
 █ 4) Doing this tho will still not prevent a way out of the above settings   ▐▌
 █ for bash.                                                                  ▐▌
 █ Here are a few examples a user could type in to bypass the steps above:    ▐▌
 █ Bash will mimic sh, not using the configurations files related to bash:    ▐▌
 █ /bin/sh                                                                    ▐▌
 █ Or if it exist:                                                            ▐▌
 █ /bin/rbash                                                                 ▐▌
 █ Then user is able to bypass logging for current session by:                ▐▌
 █ unset HISTFILE                                                             ▐▌
 █                                                                            ▐▌
 █ Or a user can launch bash with variables to not read the .bashrc file:     ▐▌
 █ /bin/bash --norc                                                           ▐▌
 █ HISTFILE=                                                                  ▐▌
 █                                                                            ▐▌
 █ //----------------------------------------------------------------------   ▐▌
 █                                                                            ▐▌
 █ If you find mistakes, have suggestions, and or questions please post at    ▐▌
 █ mewbies forum HERE - thank you.                                            ▐▌
 █                                                                            ▐▌
 █ Last update on 20 Jul '10                                                  ▐▌
 █                                                                            ▐▌
 █▌                                                                           █▌
  █▌                          -   mewbies.com   -                            █▌
   █▌                                                                       █▌
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