Linux-for-Sys-Ads/C2/User-Password-Management/English-timed

Time	Narration
00:01	Hello and welcome to the spoken tutorial on User Password Management in Linux.
00:08	In this tutorial we will learn about Changing user password
00:14	Locking and unlocking a password
00:17	Password removal
00:20	Changing the password expiry information
00:24	We will do this through some examples.
00:28	To record this tutorial, I am using Ubuntu Linux 16.04 OS
00:35	To practice this tutorial, you should have gone through earlier Linux System Administration tutorials on this website and
00:46	You must have root access to your computer.
00:51	In this tutorial we will learn about passwd command.
00:56	As the name suggests, passwd command is used to change the password of users.
01:04	Earlier in the series, we had created a user amit.
01:09	Now suppose he forgot his password.
01:13	So as a system administrator, you have to reset his password.
01:19	Let’s learn how to do this.
01:22	Open the Terminal by pressing Ctrl, Alt and T keys simultaneously on the keyboard.
01:31	First, we should login as the superuser or root user.
01:37	To do so type: sudo space su And press Enter.
01:45	Type our password and then press Enter.
01:50	Notice, our login prompt has changed to a hash symbol.
01:55	This indicates that we are in the root user mode.
02:00	Here onwards, please remember to press the Enter key after typing each command.
02:07	On the terminal type passwd space amit
02:13	It will ask you to type a new password.
02:17	Type the new password, say new_pass and press Enter.
02:24	Retype the same password and press Enter again.
02:29	The password has now changed.
02:32	As a system admin, you may need to change the password for the root account itself.
02:38	To do so, you should type passwd and press Enter.
02:43	When prompted, you should type your new password and press Enter.
02:49	It will prompt you to type the password once again.
02:53	So retype the same password and press Enter.
02:58	You will get a message that the password has been updated successfully.
03:04	Password status information related to a user account can be displayed, as well.
03:11	This is done by using hyphen capital S with the passwd command.
03:18	Switch to the terminal.
03:21	Type passwd space hyphen capital S space amit
03:28	The output shows seven space separated fields. Let us understand them one by one.
03:36	Suppose, your output shows this.
03:40	The first field is the username.
03:44	The second field indicates whether the user account: has a locked password (L), has no password (NP), or has a usable password (P).
03:58	The third field gives the date of the last password change.
04:04	Fourth to seventh fields indicate password expiry information.
04:10	The fields are minimum age, maximum age, warning period, and inactivity period for the password.
04:22	These ages are expressed in days.
04:26	We will discuss these in a couple of minutes.
04:30	Notice user amit now has a usable password.
04:35	We have changed our password just now.
04:39	So, the third field is showing today’s date 16th Jan 2019. It may be different in your case.
04:50	As a system admin, you may need to check the password status of all the user accounts.
04:57	For this, we will use the option small a along with capital S.
05:04	Type passwd space hyphen small a capital S
05:12	Notice, the password status of the user accounts are shown here.
05:18	Now, as a system admin you may need to lock a user’s password for some reason.
05:25	To lock the password for user amit, type passwd space hyphen l space amit
05:36	Press the up arrow key thrice to get back the command for showing password status of user amit.
05:44	Notice, the status is now L.
05:48	This means the password is locked now.
05:52	We also know about /etc/shadow file.
05:58	It stores the encrypted values of all users’ passwords.
06:03	Type cat space /etc/shadow
06:12	Notice, you have an exclamation mark added before the encrypted password for the user amit.
06:20	Now, this password field cannot be matched by any possible encrypted value.
06:27	Note that, this will not disable the user account. It will simply lock the password.
06:34	So now the user cannot use this password to login to the system.
06:40	The user cannot change the password.
06:44	But, the user can still login to the user account by any other mechanism.
06:51	It is possible to do so by other ways, which do not refer to the passwd file.
06:58	For example: ssh key authentication.
07:03	Login through ssh key authentication will be covered in subsequent tutorials.
07:09	Now, to unlock the password, type: passwd space hyphen u space amit
07:19	This will restore the password to its original value.
07:24	Recall the command for showing the password status for the user amit
07:30	Notice, the Status is now P.
07:34	Which means that the password is usable now.
07:38	Recall the command to display /etc/shadow file.
07:45	Notice that the exclamation mark is removed now for the user amit.
07:51	It means the password is not locked anymore.
07:56	As system admin, you can delete a user’s password also.
08:02	To delete the password for user amit, type passwd space -d space amit
08:12	So, the password for the user amit has been removed.
08:17	It is a quick way to disable a user’s password.
08:21	Recall the command for showing the password status for the user amit
08:27	Notice that the password status is now NP. So, password is not set for user amit.
08:37	Next, let’s look at password expiry information.
08:42	To display the user’s password expiry information, we had used passwd hyphen capital S option
08:52	We can also use chage command with the option small L
08:59	This gives the output in a more user-friendly format.
09:04	To view the information about user amit, switch to the terminal and type: chage space hyphen l space amit
09:17	Notice that we have a lot of information in the output.
09:22	Let us look at them one by one.
09:25	See, it is showing the minimum number of days between password change as 0
09:32	A value of 0 indicates that the user is allowed to change his or her password anytime.
09:40	The system admin can set minimum number of days between password changes using passwd with -n option.
09:50	Let us set this, so that the user amit can change his password only after 30 days from the previous one.
09:59	To do that, type passwd space -n space 30 space amit
10:09	Recall the chage command for the user amit.
10:13	So now, amit is allowed to change his password only after 30 days.
10:20	Notice, maximum number of days between password change is shown as 99999 days. It is a very long time.
10:32	It practically means that the password will never expire.
10:37	To customize the maximum number of days for which the user password remains valid, use -x option
10:45	So let us change the setting such that user amit’s password is set to a maximum of 180 days.
10:55	Type: passwd space hyphen x space 180 space amit
11:04	Recall the chage command for the user amit.
11:08	This message indicates that amit’s password will be valid for 180 days only.
11:15	After 180 days, user amit will have to change his password.
11:21	Notice, for now, the user will get a warning message 7 days before the password expires.
11:29	You can also set specific number of days for the warning message before the password expires. Let me set it as 10 days.
11:40	Type passwd space hyphen w space 10 space amit
11:49	Let’s recall the chage command for the user amit.
11:54	So, this will give warning message to the user 10 days before password expiry.
12:01	The message will state that his or her password is going to expire.
12:07	How can we force the user to change their password during their next login?
12:13	For that we have to use passwd command with -e option.
12:20	Type passwd space -e space amit
12:26	It will expire the user’s password immediately.
12:31	So, the user will be forced to change their password at their next login attempt.
12:38	Notice, it says password expiry information has changed.
12:44	Recall the chage command for the user amit.
12:49	So, password must be changed.
12:53	Now suppose the user’s password has already expired.
12:58	After password expiry, you can give the user a grace period.
13:04	The user will be able to change the login password within that grace period.
13:10	Otherwise, the user account will be disabled permanently.
13:15	That grace period is called period of inactivity.
13:20	You can set this inactivity period with the help of hyphen i option.
13:26	Let us set the grace period as 20 days for user amit.
13:32	Type passwd space hyphen i space 20 space amit
13:40	Notice, the user password information has now changed.
13:45	Till now, we have executed passwd command with only one option at a time.
13:52	Please note, you can also combine multiple options in a single command.
13:58	For example: This command sets the minimum and maximum days between password change as 10 and 20 respectively.
14:10	To exit from the root user access, Type exit
14:15	This brings us to the end of this tutorial. Let us summarize.
14:22	In this tutorial we learnt about- Changing password
14:27	Locking and unlocking password
14:30	Password removal
14:32	Changing password expiry information
14:36	As an assignment- Change password expiry information of the user amit as follows
14:44	Minimum number of days between password change: 20 days
14:49	Maximum number of days between password change: 100 days
14:54	Period of inactivity: 5 days
14:58	Use a single command to execute all of the above
15:03	Check the password expiry information by using chage command
15:09	Check password status by using the passwd command with the required option
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15:45	The script has been contributed by Antara and this is Praveen from IIT Bombay signing off. Thank you for joining.

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