Knowledge check question editing /etc/passwd
Kc 30.1 has me confused. The one option is the following:
edit /etc/passwd with vipw and add !! to the second field
I selected this because it does work, however this answer is shown to be incorrect.
(The KC question is to select all answers that apply to lock a user account)
Am I missing something, or perhaps it should be marked correct?
Thank you
Best Answers
-
Hi @andre.kit ,
You are right! I just did a small test case, and editing /etc/passwd (second field) with '!!' locks the account. I was researching if there is any difference between 'locking' and 'disabling', and I didn't find anything at the first search. But 'man passws(1)' shows the following:
-l, --lock
Lock the password of the named account. This option disables a password by changing it to a value which matches no possible encrypted value (it adds a ´!´ at the beginning of the password).Note that this does not disable the account. The user may still be able to login using another authentication token (e.g. an SSH key). To disable the account, administrators should use usermod --expiredate 1 (this set the account's expire date to Jan 2, 1970).
Users with a locked password are not allowed to change their password.
So, as far as I understand at the moment, there is a small difference between locking and disabling. I'm gonna double check it and I'll update this thread later, but it seems you are right
Regards,
Luis.1 -
Hello andre.kit , Luis
I did some checking as well, the /etc/passwd file entry #2 (password) needs to be an "x" to function, any other or additional characters are passed along to "crypt(3)" and will cause a failure in authentication. This is the same for the /etc/shadow file, any changes to the password entry will cause a failure.Now the kicker, changing the /etc/passwd, 2nd entry to "xx" will inhibit normal login (including ssh) however, I can still
launch a process as the user and run programs. Consider:$ sudo su - student ## does not check the password for student because su was launched as root and now other programs can be run student as long as additional authentication is not required.
As for the question, yes, it need to be updated.
To "lock" an account I would use "sudo usermod -e 1 -L .
6 -
Hi Andre,
I'm not pretty sure of that, but we are working on this. Look at what 'man usermod(8)' says:
[...]
-L, --lock
Lock a user's password. This puts a '!' in front of the encrypted password, effectively disabling the password. You can't use this option with -p or -U.Note: if you wish to lock the account (not only access with a password), you should also set the EXPIRE_DATE to 1.
[...]
And for locking the account we use the 'chage' command.
Look what the question in KC 30.1 says: "For a system capable of password aging on a per user basis, which of the following are valid ways of locking a user account? Select all answers that apply".
So, I think we should include or select the 'chage' tool. I'm still unsure about usermod and passwd, as these tools can lock the password but not the account (and those are slightly different things).
So, we are still looking at this.
Regards,
Luis.5
Answers
-
Thank you Luis
To be technical, due to the word "lock" being used in the question, the only correct answer, in my opinion, would be passwd -l. Perhaps if the question was phrased something like "... how to prohibit a user account from login with a password ..."; This would include all the
!
hacks, expiry and /bin/nologin shell.Thanks again
Andre
0 -
Hi @lee42x !
I just saw your comment, I was writing when you commented. So, 'sudo usermod -e 1 -L ' looks good to lock the account. But we should add 'sudo chage -E 1 ', as in that case the account will get expired and locked (you won't be able to ssh to it).
Many regards!
Luis.0 -
The "-e1" in usermod will sets the expiry date to "1" , don't set "-e 0" it turns expiry off.
Setting the expiry date to "1" also stops the "sudo su from functioning.1 -
We will rewrite the material for the next edition to say use chage or usermod. vipw and vigr are just too messy and dangerous to use, there are tools designed to avoid having to do this by hand and screw things up.
1
Categories
- All Categories
- 60 LFX Mentorship
- 113 LFX Mentorship: Linux Kernel
- 618 Linux Foundation IT Professional Programs
- 321 Cloud Engineer IT Professional Program
- 142 Advanced Cloud Engineer IT Professional Program
- 55 DevOps Engineer IT Professional Program
- 68 Cloud Native Developer IT Professional Program
- 6 Express Training Courses
- 6 Express Courses - Discussion Forum
- 2.3K Training Courses
- 19 LFC110 Class Forum - Discontinued
- 9 LFC131 Class Forum
- 31 LFD102 Class Forum
- 175 LFD103 Class Forum
- 22 LFD121 Class Forum
- 2 LFD137 Class Forum
- 61 LFD201 Class Forum
- 2 LFD210 Class Forum
- 1 LFD210-CN Class Forum
- 1 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum - Discontinued
- LFD237 Class Forum
- 23 LFD254 Class Forum
- 653 LFD259 Class Forum
- 108 LFD272 Class Forum
- 1 LFD272-JP クラス フォーラム
- 4 LFD273 Class Forum
- 2 LFS145 Class Forum
- 28 LFS200 Class Forum
- 740 LFS201 Class Forum - Discontinued
- 1 LFS201-JP クラス フォーラム
- 12 LFS203 Class Forum
- 92 LFS207 Class Forum
- 301 LFS211 Class Forum
- 54 LFS216 Class Forum
- 47 LFS241 Class Forum
- 41 LFS242 Class Forum
- 37 LFS243 Class Forum
- 12 LFS244 Class Forum
- 41 LFS250 Class Forum
- 1 LFS250-JP クラス フォーラム
- LFS251 Class Forum
- 142 LFS253 Class Forum
- LFS254 Class Forum
- LFS255 Class Forum
- LFS256 Class Forum
- LFS257 Class Forum
- 1.2K LFS258 Class Forum
- 10 LFS258-JP クラス フォーラム
- 106 LFS260 Class Forum
- 145 LFS261 Class Forum
- 39 LFS262 Class Forum
- 83 LFS263 Class Forum - Discontinued
- 15 LFS264 Class Forum - Discontinued
- 11 LFS266 Class Forum - Discontinued
- 20 LFS267 Class Forum
- 18 LFS268 Class Forum
- 26 LFS269 Class Forum
- 204 LFS272 Class Forum
- 1 LFS272-JP クラス フォーラム
- LFS274 Class Forum
- 3 LFS281 Class Forum
- 249 LFW211 Class Forum
- 177 LFW212 Class Forum
- 9 SKF100 Class Forum
- SKF200 Class Forum
- 907 Hardware
- 220 Drivers
- 74 I/O Devices
- 44 Monitors
- 116 Multimedia
- 210 Networking
- 102 Printers & Scanners
- 86 Storage
- 764 Linux Distributions
- 88 Debian
- 66 Fedora
- 15 Linux Mint
- 13 Mageia
- 24 openSUSE
- 143 Red Hat Enterprise
- 33 Slackware
- 13 SUSE Enterprise
- 357 Ubuntu
- 482 Linux System Administration
- 40 Cloud Computing
- 70 Command Line/Scripting
- Github systems admin projects
- 95 Linux Security
- 80 Network Management
- 108 System Management
- 51 Web Management
- 72 Mobile Computing
- 25 Android
- 32 Development
- 1.2K New to Linux
- 1.1K Getting Started with Linux
- 545 Off Topic
- 132 Introductions
- 223 Small Talk
- 22 Study Material
- 831 Programming and Development
- 282 Kernel Development
- 515 Software Development
- 974 Software
- 260 Applications
- 185 Command Line
- 3 Compiling/Installing
- 119 Games
- 318 Installation
- 65 All In Program
- 65 All In Forum
Upcoming Training
-
August 20, 2018
Kubernetes Administration (LFS458)
-
August 20, 2018
Linux System Administration (LFS301)
-
August 27, 2018
Open Source Virtualization (LFS462)
-
August 27, 2018
Linux Kernel Debugging and Security (LFD440)