Security covers a wide-ranging set of topics including Users, Permissions, Authentication, Authorisation, Upgrades, Firewalling, Hardening, etc.
68
votes
7answers
16k 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 ...
55
votes
17answers
6k views
Why is it bad to run 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. ...
46
votes
2answers
4k views
How can I use a passcode generator for authentication for remote logins?
I would like to strengthen the authentication of my SSH logins by adding another factor: a passcode generator device, or a passcode generation application on my mobile phone. The only obvious options ...
44
votes
5answers
22k 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 ...
43
votes
3answers
1k 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?
42
votes
8answers
2k views
What are the risks of NOT using a firewall (home computer)?
Since a password is required to be a superuser (to install and modify programs), what are the risks to not use a firewall under Ubuntu ? More particularly if I am using a NAT router ?
41
votes
2answers
3k views
How to protect Ubuntu from fork bomb
I heard someone talking about a fork bomb, I did some research and found some dreadful information about some strange looking characters people can have you type at the command line and as a result do ...
38
votes
1answer
2k 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 ...
36
votes
5answers
2k 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 ...
35
votes
7answers
7k 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?
33
votes
6answers
6k 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.
...
31
votes
7answers
6k views
Why is Ubuntu more secure than Windows or Mac OS X?
Please give some solid reasons.
Linked Question
How safe is Ubuntu?
31
votes
9answers
12k 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!
29
votes
4answers
906 views
Does Ubuntu generally post timely security updates?
Concrete issue: The Oneiric nginx package is at version 1.0.5-1, released in July 2011 according to the changelog.
The recent memory-disclosure vulnerability (advisory page, CVE-2012-1180, ...
29
votes
2answers
8k views
Why should /var/www not have chmod 777
When opening a page from my server, 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 security ...
28
votes
6answers
20k views
Easiest way to copy ssh keys to another machine?
I am lazy at home and use password authentication for my home machines. I am ready to move to key based authentication. There are many options on the web on how to do this, including catting then ...
27
votes
10answers
13k views
How can I securely erase a hard drive?
I'm planning on selling a USB external hard drive that currently contains an old Ubuntu installation with stored passwords and banking information.
How can I securely erase the drive before selling ...
27
votes
6answers
20k 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 / ...
26
votes
2answers
708 views
What precautions should I take with .debs I find on the internet?
So I was browsing the web the other day, and I came across a few places that wanted me to download .deb files - and since those are installed by root (and as such have the "powers" and capabilities of ...
26
votes
7answers
1k views
What precautions should I take when exposing my desktop directly to the internet?
I've always used my Ubuntu desktop behind the security of a router with NAT, but there have been a few times when I've had to plug it directly into an active cable modem.
In general, what precautions ...
26
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 ...
25
votes
7answers
6k 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 ...
25
votes
3answers
516 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 ...
24
votes
2answers
5k 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?
24
votes
3answers
3k 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 ...
23
votes
8answers
2k views
What do I have to do before giving away my Ubuntu machine?
I have an old laptop that is running Ubuntu. Now I want to give away this laptop, but I want to remove all private data. So what should I remove? I don't want to format the whole system, because the ...
23
votes
4answers
3k 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 ...
23
votes
8answers
4k views
What is the best way to set up a headless server?
I have a ubuntu development server at work. It is an old rack server that is located somewhere in the company's dungeon, where nobody ever goes :)The only way it can work is as a so-called headless ...
22
votes
14answers
5k 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?
22
votes
7answers
1k views
22
votes
1answer
1k views
Is Ubuntu vulnerable to recent exploits using USB sticks and automount?
I read recently that someone demonstrated a security attack on a PC via the use of automount and a USB stick.
How vulnerable am I to this attack and what steps are developers doing to be proactive ...
21
votes
4answers
4k 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.
21
votes
2answers
1k 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 ...
21
votes
6answers
7k 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 ...
20
votes
18answers
4k views
Can you recommend a password generator?
I was hoping someone could recommend a good password generator.
Extra props to the person who can name one that gives you a mnemonic to remember it as well.
20
votes
3answers
2k views
Difference between PGP and GPG
What are the main differences between PGP (Pretty Good Privacy) and GPG (GNU Privacy Guard) in relationship with security in Ubuntu and Launchpad?
20
votes
8answers
7k views
How can I encrypt data in Ubuntu One?
I'd love to use Ubuntu One features, like file storage and so on, but I don't want anyone else to access my data, USA Patriot act etc.. Things shall be encrypted so that the only place where info is ...
19
votes
3answers
362 views
What automated intrusion notification/detection setup is good for home desktop use?
I've been using Linux for quite a while now and I always feel the need to have a passive software / script setup which can alert me of any suspicious network activities like scans, failed login ...
17
votes
7answers
944 views
How should a server be secured?
Talking towards Ubuntu 10.04, server edition, what tools/practices would you recommend to secure the server?
17
votes
2answers
2k 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 ...
17
votes
3answers
16k 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 ...
16
votes
4answers
1k views
Is this command to remove old kernels safe to use?
While browsing the internet for Ubuntu articles, I came across this command:
sudo dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ...
16
votes
6answers
2k views
Where can I look for malware that may have been installed on my machine?
I want to analyze my ubuntu box to detect if it was been hacked. My question is: what are all the place where to look to discover if some malicious software are started ? The following is some kind of ...
16
votes
2answers
958 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 ...
16
votes
4answers
1k views
How to sandbox applications?
I want to run small untrusted programs, but restrict them from accessing any files outside of their folder, network access, and everything else that they don't really need. What is the simplest way to ...
16
votes
2answers
469 views
Accidentally typed password in username input, any logs to clear?
I have accidentally typed my password in SSH's interactive username prompt. Are there any log files that I should clear?
15
votes
5answers
3k 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 ...
15
votes
1answer
2k views
Update Manager does not ask for password anymore
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 ...
15
votes
2answers
11k 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 ...
15
votes
2answers
866 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 ...
