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

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125
votes
8answers
48k views

Are PPA's safe to add to my system and what are some “red flags” to watch out for?

I see a lot of interesting programs out there that can only be obtained by adding a "PPA" to the system but, if I'm understanding correctly, we should stay within the official "repositories" for ...
52
votes
8answers
24k views

What is the difference between “gksudo nautilus” and “sudo nautilus”?

I've been using gksudo nautilus and sudo nautilus through Alt+F2. What's the difference? They look very similar!
80
votes
18answers
17k views

Why is it bad to login as root?

I've often come across posts on forums or other websites where you see people joking in such a manner about running/logging in as root as if it's something awful and everyone ought to know about it. ...
134
votes
6answers
98k views

How to patch the Heartbleed bug (CVE-2014-0160) in OpenSSL?

As of today, a bug in OpenSSL has been found affecting versions 1.0.1 through 1.0.1f (inclusive) and 1.0.2-beta. Since Ubuntu 12.04, we are all vulnerable to this bug. In order to patch this ...
76
votes
8answers
39k views

How to delete file(s) in secure manner?

Is there a way to make sure that a deleted file can not be recovered? As you know, deleting a file by pressing shift-del or using trash doesn't mean that file is gone forever. It resides somewhere ...
11
votes
4answers
21k views

What antivirus programs are available?

What antivirus programs are available for Ubuntu? We previously used Symantec Endpoint Protection but it does not work in Ubuntu.
125
votes
5answers
86k views

What is the CVE-2014-6271 bash vulnerability (Shellshock) and how do I fix it?

Recently, there have been news going around regarding "CVE-2014-6271" (See USN-2362-1), which is a vulnerability in Bash. How do I know if I am affected by this, how can I fix it, and why should I ...
39
votes
2answers
17k views

Why shouldn't /var/www have chmod 777

When developing a page on a localhost, I sometimes get a "Permission denied" error which I can solve by running chmod -R 777 /var/www. However, people are telling me that this is a bad idea for ...
27
votes
14answers
9k views

Why is there no option to login as root?

Why does Ubuntu not allow the GUI users to login as root at the time of system start up like administrator in Windows? Why they are restricting us to login only through the terminal?
42
votes
6answers
16k views

What is the best way to restrict access to adult content?

I bought my kids a PC and installed 12.04 (Unity) on it. The bottom line is, I want my children to use the computer unsupervised while I have confidence they cannot access anything inappropriate. ...
18
votes
1answer
57k views

How do I scan for viruses with ClamAV?

I installed ClamAV via Terminal (Ctrl+Alt+T) with: sudo apt-get install clamav but how can I scan for viruses?
33
votes
5answers
10k views

Why is the firewall disabled by default?

Why is ufw firewall included in Ubuntu, when it is not enabled and pre-configured by default? Most users don't even know it is there, because no GUI frontend is provided.
15
votes
3answers
2k views

Risks/Disadvantages associated with Wine

Can wine as a whole or the windows applications installed via wine pose some kind of risk to an Ubuntu installation? This question arose in my mind when I read this answer to my earlier question ...
38
votes
6answers
50k views

Is there a way to password protect individual folders?

Let's say that I have a folder, within my Documents folder, that has files I want no one to access without a password. Is there a way to lock down that folder so that it's password protected / ...
43
votes
3answers
8k views

When to use pkexec vs. gksu/gksudo?

There are two general ways to run applications graphically as root (or, more generally, as another user). Programs like gksu, gksudo, and kdesudo are graphical frontends for sudo. In contrast, pkexec ...
97
votes
6answers
65k views

How can I install just security updates from the command line?

sudo apt-get upgrade installs all updates, not just security updates. I know that I can use Update Manager to select only important security updates, but is there a way to do this from the command ...
42
votes
10answers
26k views

How to harden an SSH server?

What measures can/should I take to make sure that security around my SSH server is absolutely impermeable? This will be community wiki from the start, so lets see what people does to secure their ...
17
votes
5answers
5k views

Is there a preinstalled or automatic firewall?

Does Ubuntu come with a preinstalled or automatic firewall? If not, do I need one? I've read some articles about the advantages of linux over other operating systems about security (no need to have ...
37
votes
7answers
14k views

Why is Ubuntu more secure than Windows or Mac OS X?

Please give some solid reasons. Linked Question How safe is Ubuntu?
122
votes
3answers
89k views

How do I patch/workaround SSLv3 POODLE vulnerability (CVE­-2014­-3566)?

After the BEAST attack and Heartbleed bug, now I've heard about a new vulnerability in SSL/TLS called POODLE. How do I protect myself against being exploited? Are only servers or also clients ...
29
votes
8answers
12k views

How can I encrypt data in Ubuntu One or Dropbox?

I'd love to use Ubuntu One or Dropbox features, like file storage and so on, but I don't want anyone else to access my data, USA Patriot act etc.. I want things to be encrypted so that the only place ...
22
votes
3answers
34k views

How do I setup OpenVPN so I can securely use the internet from an unsecured hotspot?

Goal: I want to be able to securely use the internet via my home PC while my notebook is connected to an open hotspot/access point. I do know that I can use a SSH tunnel/SOCKS proxy, but I don't want ...
10
votes
6answers
3k views

Why can't non-admin users install software?

This is probably something I don't understand since I am used to Windows and am only starting out with Ubuntu. I know that software in linux comes in packages what I don't understand is why can't ...
19
votes
2answers
4k views

How safe is Ubuntu?

Last week I started desktop sharing using krfb. Continuing from my last session, it appears that the process restarts itself. Two days ago I noticed messages popping up saying something like ...
59
votes
3answers
7k views

What is apparmor?

I hear a lot of talk about apparmor, I want to know the following: What is apparmor? How does apparmor work?
31
votes
2answers
32k views

How to create a restricted SSH user for port forwarding?

ændrük suggested a reverse connection for getting an easy SSH connection with someone else (for remote help). For that to work, an additional user is needed to accept the connection. This user needs ...
39
votes
7answers
11k views

What is the Ubuntu “built in virus protection”?

At ubuntu.com there is this "only in ubuntu" that says "Built in virus protection": What is the Ubuntu built it protection? What is the program in charge of this and how does it work?
38
votes
5answers
4k views

How can I prevent someone from resetting my password with a Live CD?

Recently one of my friends came over to my place, within 15 minutes he hacked my account using a Live CD and reset the password in front of me. I was baffled to see such a thing. Please guide me to ...
10
votes
3answers
5k views

How to prevent system applications (like the Software Center) from asking for password?

I'd like Software Center, Update Manager and some other system management applications to work without asking for password (like sudo does if configured with NOPASSWD) but only asking for a ...
30
votes
3answers
769 views

Is there any guarantee that software from Launchpad PPAs is free from viruses and backdoor threats?

As Linux continues to grow and develop, and the more we use Linux, the greater the threat from viruses. We also know that a virus/threat in Linux (if any) would have difficulty running or spreading ...
27
votes
4answers
2k views

How do I configure Ubuntu for a public computer?

How would you set up Ubuntu on a computer that will be used as public computer in a library? I need the following features and user restrictions: On boot, a guest user should automatically be ...
19
votes
2answers
1k views

How is the system kept secure?

I understand that if any malware made it's way into a Linux system, it will, at most, gain a user-level privilege and ruin anything within the particular user's reach, i.e. the user's own files. But ...
14
votes
6answers
11k views

Ubuntu One behind a proxy, how to make it work?

I am behind a web proxy server at work (no authentication) and I have set it up in Gnome (configuration applied system-wide). It works fine for accessing internet with a browser, but numerous ...
10
votes
3answers
20k views

How to change LUKS passphrase?

Having installed Ubuntu 11.10 with whole disk encryption and LVM, I need to provide a way for users to easily change LUKS passphrase. Preferably, this should be done using GUI tools, thus, enabling ...
20
votes
6answers
15k views

What Can Be Done To Secure Ubuntu Server?

I have a project to secure Ubuntu Server as much as I can. The server is a web hosting server. The server will be running LAMP , Mail , and DNS.
26
votes
5answers
7k views

What if I run a virus/trojan Windows EXE on Ubuntu with Wine?

I've got a file said to contain information I was looking for. Unfortunately it is an executable instead of DOC (as it was meant to be) and the site I've download it from looks suspicious for me. If I ...
22
votes
4answers
16k views

How can I detect a keylogger on my system?

How could I know if there's a keylogger in my system, or at least if one is active right now?
4
votes
5answers
4k views

How can I lock down ubuntu?

I am working on a small project. I have about 20 computers with Ubuntu 10.04 on them, which will be used in a computer lab for elementary, middle, high school and college kids. Some seniors and new ...
19
votes
2answers
1k views

Why should I trust the “System program problem detected” dialog?

This always shows up a few minutes after I log in: I have no idea what it is. If I click Report problem, it asks for my password: This is exactly what I would do if I wanted to steal someone's ...
4
votes
1answer
2k views

Wireless with WEP extremely slow on an Acer Timeline 4810T with a Centrino Wireless-N 1000

I've upgraded an Acer Timeline 4810T to Ubuntu 11.10. Everything works fine except for the darn wireless interface (network manager). I just tested the wireless interface over a non-encrypted signal ...
53
votes
1answer
5k views

Can I make the webcam take a picture when an incorrect password is entered?

I am using a laptop . I was thinking to have a support in my Ubuntu machine. When an incorrect password is entered, a picture is taken later revealing who has been trying to gain access. I have ...
48
votes
2answers
49k views

How do I keep track of failed SSH log-in attempts?

I'd like to see if somebody has been trying to log-in by brute-force into my Ubuntu 12.04 server over SSH. How can I see if such activities have been taking place?
25
votes
7answers
13k views

Basic Ubuntu FTP Server

I would like to setup a basic FTP server on my Ubuntu Server install. I have been playing with VSFTPD, but am having issues getting the server to allow me to create directories and copy files. I ...
17
votes
1answer
3k views

Update Manager does not ask for password anymore [duplicate]

I have realized this behaviour recently. Before that each time the update manager poped up to tell me there are updates and I tell it to install them it will ask me for a password. But since recently ...
28
votes
2answers
2k views

Should security updates always be installed?

We are a small shop, with no real sysadmin. So developers (Java EE) also try to maintain Ubuntu server 12.04. When I login a terminal and I see messages like: 6 packages can be updated. 6 updates ...
8
votes
3answers
12k views

How to disable cryptswap?

How can I disable cryptswap? I would like an unencrypted swap like before. This is on an ubuntu 9.10 system.
6
votes
2answers
1k views

How to secure grub recovery mode

When I boot system in to recovery mode from GRUB menu, I can get in to all powerful root without entering any password, thus insecure. How I can secure this and ensure that a password is asked every ...
5
votes
1answer
219 views

What security policies exist in place for packages and scripts?

I did have used Microsoft Windows since Windows 98 to Windows 7. I have found lots of security vulnerabilities by myself about how viruses, worms, spyware etc. compromises the system. Microsoft ...
0
votes
2answers
642 views

Best Practice for Installing Java on Ubuntu / is it secure?

Much has been said about the security risks associated with Java. However the burp suite (pen test) depends on Java. Is it secure to install Java? if so, how to properly do it? My Ubuntu is a web ...
7
votes
2answers
1k views

What is a security update?

Why are some updates called Important security updates? How are they different from other updates? Is my system insecure, If I don't install them? How can there be very frequent security updates? ...