Questions tagged [security]

Security covers a wide-ranging set of topics including Users, Permissions, Authentication, Authorisation, Upgrades, Firewalling, Hardening, etc.

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How to check who opened files on UBUNTU 18.4

I use Ubuntu 18.04 Today, I left the computer on and no one used it. And when I came back home, I saw a lot of directories, files, and images opened. I wonder if anyone hacked into my computer?
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My private ssh key suddenly requires a passphrase (which I don't have)

I have always used my ssh key without a passphrase. The last time I used it was yesterday. But now, it suddenly requires a passphrase: > ssh-keygen -y Enter file in which the key is (/home/...
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2answers
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Is it safe to write sensitive data to terminal?

I have a program to store passwords protected, however, interface is the terminal and passwords are all written visibly. I have very limited knowledge on the security, so couldn't be sure if it is ...
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Does Chromium web browser store passwords more securely than Firefox?

As far as I know Chromium uses some keyring, so if you for example make Ubuntu not ask password on login, Chromium will ask you for password when it is launched. Is it different when comparing to ...
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Cannot save files in Kdenlive snap, why not?

For some reason, Kdenlive (snap version) is not saving files. The program things it is saving, but nothing is actually written to the disk. I've enabled removable drive access permissions, but that ...
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How one can prevent NIS from exporting users to client machines? [closed]

How one can prevent NIS from exporting root users and other system users on server to the client machine while setting up the NIS?
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Why can I access any linux /home/user files booting from a live distro? [duplicate]

Is it not a security risk, that someone could access all the documents of a user just by booting a distro live cd?
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How can I better secure my Samba server?

So I was checking out my bandwidth on my server because it was quite higher than usual. Well I have found out that there's been thousands of people from different IP's trying to brute force their way ...
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2answers
391 views

20.04, /etc/securetty: No such file or directory [closed]

Just updated to 20.04 final release, and I'm seeing these messages in /var/log/auth.log... May 14 06:29:52 Satellite-E55 gdm-password]: pam_unix(gdm-password:auth): Couldn't open /etc/securetty: No ...
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How to get a USB to access to specific partition only. Having no read\write on others [closed]

(Skip to question) About me Hey guys, new to linux. Looking to stay part of this community and parrotsec. A little about me and may understand what I'm going through and looking for. I have been ...
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Each update or upgrade show following comments i dont know if its harmful or not…can someone guide me about it [duplicate]

Each update or upgrade show following comments i dont know if its harmful or not...can someone guide me about it E: The repository 'http://download.opensuse.org/repositories/home:/strycore/...
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Disabling Webcam by blacklisting driver - what are the consequences?

I am a new Ubuntu user, and for security reasons I would like to disable my webcam unless I need it. The most appealing solution to do so seems to blacklist the webcam driver, as outlined here. ...
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How do I force apt to use HTTPS only?

How do I force apt to use HTTPS only? This question aims to provide a comprehensive actionable answer to questions 1, 2, and 3, but is worded in a manner that better fits with the guidelines and ...
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Two Factor Authentification enabled - No login possible

I followed this tutorial to enable 2FA on my server. I followed the tutorial on the root user, as I wanted the root user only to get secures via 2FA. As I wanted to relogin and try out if everything ...
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Ubuntu 20.04 Automatic Login Not Working Consistently

I installed 20.04 on new hardware and configured Users to use automatic login since the machine will be used by multiple users in the household and will not store valuable data. Settings -> Users ...
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Resources for 800-171 compliance with Ubuntu 18.04?

Coming from the Red Hat world, automating SCAP benchmarks for 800-171 compliance is a snap because the profile is baked into the SSG. NIST 800-171 is a very common control set in the US, and will ...
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How much security is provided by secure boot?

When booting the OS, when we press F2 on start up, the bios screen comes up. Here, we have the option of enabling secure boot. I am given to understand that now the firmware verifies the signature of ...
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How to verify genuineness of live bootable USB ubuntu drive?

I downloaded the Ubuntu iso and did a shasum on it as per the instructions on the website and it matched with the value of the website. Now, the ISO needs to be mounted on a USB drive. There is an ...
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Ubuntu 18.04LTS reboots suddenly once update app pressed?

Ubuntu 18.04LTS, rebooted suddenly once update app pressed? It’s a AMD Ryzen 5 2600 cpu, with Gigabyte AB350M- Gaming 3 motherboard with latest bios installed. I did try to upgrade it to 20.04LTS, ...
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Can we set ON a device which is OFF in the BIOS

I use Ubuntu Studio 19.10 (I'm still waiting for the 20.04 upgrade, it seems to be not available in my country, yet). In the BIOS system of my Laptop, I set OFF the internal Webcam and Microphone (...
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question on password security - resetting admin password with grub menu root shell prompt

I recently forgot my admin account password on my laptop. I managed to enter the grub menu at boot, getting on to root shell (recovery mode --> drop into root shell prompt). From there all I had to do ...
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Why does my website get redirected to another

I have a Apache2 web server in Ubuntu. Usually my domain name works, but sometimes it gets redirected to some other spam website that pretends like it’s mine. If I type in my IP then it always ...
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How to upgrade from a possibly compromised ubuntu system to a new system?

I have Ubuntu 14.04 on my machine. Since I could have installed applications from some untrusted sources, I suspect that my system could be compromised and could contain malware. Now, if I want to ...
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How to make Evolution overwrite email message before expudning it?

Is there any way to make Evolution overwrite an email message before the message is expunged? I can go to $HOME/.local/share/evolution/mail, use grep to find the file in question, then use shred on ...
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1answer
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Ubuntu 20.04 - how to set lower SSL security level?

I'd like to ask if there's a way to lower SSL security level to 1 on Ubuntu 20.04, since I'm receiving: 141A318A:SSL routines:tls_process_ske_dhe:dh key too small when trying to curl the website. ...
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Can evolution skip QR security?

For my work e-mail I currently use Evolution and this was not a problem for the Exchange server at one place, whose web-mail has additional QR-based authorisation, and the Outlook 365 server that did ...
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How to keep the tor browser updated?

To follow up on a few tor questions, how is the tor browser kept up-to-date? Surely, surely, manually downloading it periodically isn't the norm. see also: Tor Browser doesnt launch how to launch ...
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What security best practices should be followed while downloading and installing software?

Is it necessary to check that the software we are downloading comes from a trustworthy source? Or can software in the official Ubuntu repositories be automatically trusted to be safe? I am especially ...
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Ubuntu security updates and bug fixes solution for multiple machines

Good morning, I am new to Linux and looking at switching to Linux OS from Windows possibly Ubuntu. And I am trying to find out if there are any easier wayS to manage updates for multiple laptops like ...
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Where and how do I report security concerns regarding Ubuntu 20.04 LTS and Fingerprint reader login access? [duplicate]

So I installed Ubuntu 20.04 LTS on my Lenovo ThinkPad T510. I set up my laptop nicely and enable fingerprint login. This evening, my wife was messing my my laptop that was on the login screen and she ...
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15 views

Shut down the computer after 3 failed login attempts

I would like to set up the PAM module such that the system is shut down after 3 failed login attempts. I know pam_exec can be used to run a script with one failure. With more than one failure, I ...
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At login screen, a progress bar logs me in without asking for password

first time here for asking a question :) Everything is in the title : the issue happens when I'm at the login screen after booting my laptop, at the screen where I have to choose the account I want ...
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Can’t keep activated Let’s Encrypt setting?

My environment : a remote VPS running distro Ubuntu 18.04 LTS (up to date) For the first time since 4 years and more..., I received an alert message from my hosting provider, saying that because of ...
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2answers
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MITM-attack? I have an untrusted certificate dns.hinet.net

Since a few weeks a pop-up window appears (sometimes) after start-up of my Ubuntu 16.4 system, see this picture: The title in the window bar says: "Untrusted certificate". The 1st line in the window ...
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How to find out security code in kyan in which Ubuntu 16.04 is installed

Unexpectedly I pressed menu key in which security code key got activated ,I don't know security code so please help me with the answer
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What steps must be taken to secure my Ubuntu installation from keyloggers and screen capture software? [duplicate]

I have a Ubuntu desktop. I want to protect my installation from software which can steal passwords I enter by logging keystokes or capturing the screen in case of a graphical on screen keyboard. I am ...
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23 views

Aliasing with reserved keyword or command alias? (Overwriting)

Is it possible to make an alias with a name that is already reserved as a keyword/command in Linux and Ubuntu? If I alias passwd or chpasswd with the same name but use additional parameters so that ...
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1answer
118 views

Microsoft Teams Ubuntu/Debian package secretly adds APT source and APT key

After installing Microsoft Teams, I noticed that the following files were created on my system: /etc/apt/sources.list.d/teams.list /etc/apt/trusted.gpg.d/microsoft.gpg There was no request / ...
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2answers
38 views

Location for SSL certificates, how to secure them?

I have a nodeStatic app on an ubuntu server. A domain links to the server. Now I need to add SSL certificates: var fs = require('fs'); var options = { key: fs.readFileSync('ssl/privatekey.pem')....
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Hosting an Ubuntu virtual machine online and its security

So I'm working on a project where I need to host a Ubuntu machine online on a remote server which a user will be able to access through the internet, by logging in using SSH. The main thing that we ...
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1answer
28 views

TCP SACK PANIC - Kernel vulnerabilities FIXED into Ubuntu 16.04.6 LTS (GNU/Linux 4.4.0-176-generic x86_64)?

I read Ubuntu updates for TCP SACK Panic vulnerabilities article so I updated my Ubuntu server 16.04.6 LTS getting GNU/Linux 4.4.0-176-generic x86_64. Then i rebooted the server. Is this security ...
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22 views

Paid disk encryption software for Ubuntu 18xx and above

Please suggest a paid disc encryption software for Ubuntu 18xx and above, need a paid software so that i can rely on the support when needed.
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2answers
74 views

Should Ubuntu be installed in UEFI mode?

Ubuntu supports UEFI and Secure Boot, but it's unclear if they should be used. From my reading, it seems that using UEFI improves security, but the Ubuntu UEFI documentation says: If you're ...
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49 views

Virtual Machine Host and Guest Nic Share Security Concern

I suppose I should start by describing desired end goal of this project... I'd like to set up my desktop to run as a guest on top of a host OS. It might be a vm or container, or whatever, I haven't ...
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64 views

Linux security(?) issue Ctrl+Alt+F7/F8

Ubuntu Desktop 18.04 LTS amd64. User A logs into Ubuntu. Then he switches to user B. Now user B can access user A's GUI by pressing Ctrl+Alt+F7. User A can also access user B's GUI by pressing Ctrl+...
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1answer
49 views

Error: bad port during put port range

I try to allow port using ufw like below but error:bad port appears test:~# sudo ufw allow 45000:65536/tcp ERROR: Bad port
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1answer
38 views

Adding negation to the time match of iptables. What does it mean?

I want to allow access to traffic only from 07:00 to 15:00. I want to use negation since I have other iptables rules. Does using negation in the following exemple meet my requirements about time slot?...
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1answer
247 views

LightDM: How can I trigger a bash command everytime someone fail to login?

I'd like to take and save a picture from the webcam, every time someone tries to login into the system and fails. I know I can do that with: mplayer -vo png -frames 1 tv:// The question is: How can ...
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39 views

Possible to clone the encrypted disk of a computer that's logged into but locked in sleep mode?

My entire disk is encrypted with luks. If someone steals my laptop while it's on and I've already logged into the system by decrypting the disk with the luks password but my system locked in sleep ...
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2answers
72 views

My username, password and i.p. were public. Was I hacked?

Through a series of poor choices, the username, root password, and i.p. address to my Ubuntu machine were pushed to a public repository. Now, I've changed my password and purged the repo of the ...

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