Ubuntu16 - useradd or adduser
Hey guys, recently been trying to work on labs 28.1 and 28.2. I am able to complete 28.1 but 28.2 just does not work.
For 28.2 we are supposed to get a restricted shell. Doing rbash -r in the shell works and I cannot change dirs or PATH. However copying "sudo ln /bin/bash /bin/rbash" then creating a "useradd -s /bin/rbash fool" does not work once I "sudo su - fool" then I test changing directories and changing PATH cariable and I am still able to do it.
Using the "useradd" command was not working when trying to create a new home directory. I noticed in ubuntu 16 it is telling me to use "adduser." With "addsuer" I can easily create the home dirs I want, change shell path (but rbash still not working), and remove the user with "deluser" command.
Either way, using "useradd" or "adduser" I cannot get a restricted shell to work once I "sudo su - user."
Thanks!
Comments
-
Hi,
I was able to reproduce the issue on Ubuntu 16. We are checking on this and we will contact you as soon as we have news.
Thanks,
Luis.
0 -
Hello Luis,
any news on the above.
I am having exactly the same issue and I cannot track any solution for that.
OS: Ubuntu 18.040 -
It's clearly a bug in Ubuntu -- I verified that you get the same behaviour in 18.02. If you do "man rbash" on ubuntu you will find the behaviour is a direct contradiction to what is supposed to happen. And the symbolic link is already set up on ubuntu by default. I think "rbash" is rarely used so I would not worry much. But it is a bug. We could put a note in the next course version
(if we haven't already, I forget). Thanks0 -
Actually, in the lab I have on my machine, it says right after the lab:
Please Note
• On some distributions, notably some Ubuntu-based versions, there is a bug which prevents this lab from behaving
properly. On RedHat-based distributions, the above correct behaviour is observed.Don't you have this in your lab? right after the solution.
1 -
Yeap. Now I can see the note on the next page
Many thanks though for your reply.1 -
Hello hello,
I have asked about this issue on the askubuntu forum.One of the advice was to reload the shell.
I can confirm that after reboot, rbash behaves as expected, the all restrictions are on in place.https://askubuntu.com/questions/1244253/rbash-does-not-work-when-set-as-the-default-shell-for-a-user
1 -
After consulting with smarter people than myself, I became convinced using "rbash" is obsolete and there are much better ways of controlling people today, such as the use of linux security modules such as LSM.
THe rbash discussion is a relic and will be removed in future versions. This is why such a buggy behaviour can persist in Ubuntu (no one caresprobably ). So don't worry about this detail
1
Categories
- 8.9K All Categories
- 13 LFX Mentorship
- 66 LFX Mentorship: Linux Kernel
- 363 Linux Foundation Boot Camps
- 230 Cloud Engineer Boot Camp
- 70 Advanced Cloud Engineer Boot Camp
- 25 DevOps Engineer Boot Camp
- 5 Cloud Native Developer Boot Camp
- 845 Training Courses
- 15 LFC110 Class Forum
- 16 LFD102 Class Forum
- 102 LFD103 Class Forum
- 3 LFD121 Class Forum
- 55 LFD201 Class Forum
- 1 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum
- 19 LFD254 Class Forum
- 431 LFD259 Class Forum
- 85 LFD272 Class Forum
- 1 LFD272-JP クラス フォーラム
- 16 LFS200 Class Forum
- 692 LFS201 Class Forum
- LFS201-JP クラス フォーラム
- 271 LFS211 Class Forum
- 50 LFS216 Class Forum
- 26 LFS241 Class Forum
- 27 LFS242 Class Forum
- 19 LFS243 Class Forum
- 6 LFS244 Class Forum
- 9 LFS250 Class Forum
- LFS250-JP クラス フォーラム
- 107 LFS253 Class Forum
- 789 LFS258 Class Forum
- 7 LFS258-JP クラス フォーラム
- 51 LFS260 Class Forum
- 78 LFS261 Class Forum
- 13 LFS262 Class Forum
- 76 LFS263 Class Forum
- 14 LFS264 Class Forum
- 10 LFS266 Class Forum
- 8 LFS267 Class Forum
- 9 LFS268 Class Forum
- 6 LFS269 Class Forum
- 180 LFS272 Class Forum
- 1 LFS272-JP クラス フォーラム
- 187 LFW211 Class Forum
- 103 LFW212 Class Forum
- 878 Hardware
- 207 Drivers
- 74 I/O Devices
- 43 Monitors
- 115 Multimedia
- 204 Networking
- 98 Printers & Scanners
- 82 Storage
- 723 Linux Distributions
- 81 Debian
- 64 Fedora
- 12 Linux Mint
- 13 Mageia
- 22 openSUSE
- 126 Red Hat Enterprise
- 33 Slackware
- 13 SUSE Enterprise
- 347 Ubuntu
- 447 Linux System Administration
- 33 Cloud Computing
- 64 Command Line/Scripting
- Github systems admin projects
- 89 Linux Security
- 73 Network Management
- 105 System Management
- 45 Web Management
- 50 Mobile Computing
- 18 Android
- 19 Development
- 1.2K New to Linux
- 1.1K Getting Started with Linux
- 499 Off Topic
- 119 Introductions
- 193 Small Talk
- 19 Study Material
- 747 Programming and Development
- 240 Kernel Development
- 473 Software Development
- 902 Software
- 247 Applications
- 178 Command Line
- 2 Compiling/Installing
- 72 Games
- 314 Installation
- 20 All In Program
- 20 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)