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

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24
votes
3answers
47k 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 ...
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 ...
15
votes
6answers
12k 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 ...
9
votes
3answers
20k 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.
10
votes
2answers
2k 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? ...
5
votes
1answer
272 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 ...
7
votes
4answers
6k views

Why is X11 a security risk in servers?

I remember reading that servers do not have a GUI because X11 is a security risk. Why?
5
votes
3answers
6k views

ClamAV: PUA.Win.Exploit.CVE_2012_0110 FOUND (/usr/share/mime/mime.cache)

I recently scanned my system with (I am running the latest version of ClamAV and my definitions are up-to-date): sudo clamscan -r --detect-pua --infected --bell / And this one was of the results: /...
2
votes
2answers
1k views

verifiying ubuntu iso with repository gpg-keys

I want to verify that a downloaded ISO is not being poisoned by the NSA or any other immoral agent. To do this I would very much use a signing-checking way. I am aware of VerifyIsoHowto. Still I am ...
25
votes
6answers
25k 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.
62
votes
6answers
9k views

How to secure my laptop so that hacking by physical access is not possible?

I messed up my system earlier, I was greeted with a black screen, when booting in to Ubuntu. When I started up my laptop, I selected the recovery option from the grub menu, and chose fallback at root ...
29
votes
8answers
6k 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
2answers
17k views

What is the 'ptrace_scope' workaround for Wine programs and are there any risks?

To run certain Windows programs in WINE you need to this workaround: echo 0|sudo tee /proc/sys/kernel/yama/ptrace_scope According to the support websites, this is due to a bug in the Ubuntu kernel ...
52
votes
2answers
63k views

How can I allow SSH password authentication from only certain IP addresses?

I'd like to allow SSH password authentication from only a certain subnet. I see the option to disallow it globally in /etc/ssh/sshd_config: # Change to no to disable tunnelled clear text passwords #...
9
votes
2answers
22k views

Driver for Validity Sensors Fingerprint scanner

prakhar@pr3d4tOr:~$ lsusb -s 001:003 -v Bus 001 Device 003: ID 138a:0018 Validity Sensors, Inc. Fingerprint scanner Couldn't open device, some information will be missing Device Descriptor: bLength ...
32
votes
4answers
30k 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?
29
votes
2answers
803 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 ...
16
votes
6answers
30k views

How to secure ubuntu server from bruteforce ssh attacks?

I have my passwords secure, but I heard people complaining about perfomance of a server going down drastically when a bruteforce attack is taking place. How can I secure my ubuntu 10.10 server from ...
24
votes
2answers
9k views

Disable password access through SSH?

I'm setting up a server for backing up my desktop box remotely. I want to prevent remote password access to the server, permitting only users with private keys (AKA my desktop box) to access it. How ...
18
votes
2answers
2k views

Is it a bad idea to run SELinux and AppArmor at the same time?

My corporate policy says that Linux boxes must be secured with SELinux (so that a security auditor can check the 'yes, we're extremely secure!' checkbox for each server). I had hoped to take ...
18
votes
6answers
29k views

How can I audit users and access attempts to SSH on my server?

I've had a few security problems with a server of mine, a few SSH users have been setting up fires aka giving problems. I would like to: Track user logins and logouts Track activity of these SSH, ...
33
votes
2answers
4k views

Why is everybody so concerned about etc/passwd?

Here is the content of my vagrant machine of this particular file: root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin bin:x:2:2:bin:/bin:/usr/sbin/nologin sys:x:3:3:sys:/...
21
votes
2answers
26k views

chkrootkit says /sbin/init is infected, what does that mean?

I recently ran chkrootkit and got the following line: Searching for Suckit rootkit... Warning: /sbin/init INFECTED What does this mean exactly? I heard this was a false positive, ...
21
votes
2answers
17k views

Untrusted application launcher?

Some time ago, Ubuntu introduced a Security "feature", that would only allow trusted .desktop apps to be run, on other apps it would pop up a message. Nothing new so far, However, said Message used ...
11
votes
2answers
4k views

What is the least insecure way to store a password that is used by a script?

I have a Bash script that automatically authenticates with a service using my username and password. The credentials are currently stored as plain text within the script. What precautions should I ...
5
votes
2answers
2k views

How to truly secure a hard-drive?

When I boot from an USB stick into my laptop I am able to mount and connect through chroot to the my hard drive and browse my files without a problem, while this has been something very very useful in ...
8
votes
1answer
2k views

Why should I use gksudo for Gtk apps instead of sudo? [duplicate]

I read somewhere that people should use gksudo for applications that use the Gtk GUI instead of sudo? What's the reasoning for this?
4
votes
2answers
12k views

How do I check if someone accessed my computer?

I need to check the list of files accessed in my computer (ex: yesterday on particular time). Is it possible? Or I need to check whether anybody accessed my computer (when I left it unlocked) or ...
0
votes
2answers
2k 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 ...
19
votes
2answers
2k 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 ...
3
votes
1answer
2k views

Sudo is also user login password - why? how to change?

When installing Ubuntu I can create a user with an encrypted folder, what I always do. Now after the installation the login password for this user is also the sudo password. Is that how it should be? ...
61
votes
2answers
9k 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 ...
24
votes
3answers
2k 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 ...
35
votes
6answers
6k views

What's wrong with using sudo?

In a comment here I've been told that unnecessarily using sudo should be avoided. While it wasn't needed in that particular case, I don't see any harm in using it. I think that when executing trivial ...
24
votes
4answers
72k views

How to disable IPv6 permanently?

How can we disable IPv6 system wide via terminal commands? I've read editing /etc/modprobe.d/aliases and replacing: alias net-pf-10 ipv6 with: alias net-pf-10 off alias ipv6 off Is this safe ...
20
votes
3answers
7k 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/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/...
15
votes
2answers
3k views

How can I tell that apparmor is working?

Some questions I want answered in the answer: How do I know if apparmor is running? How can I tell if it's working well?
10
votes
5answers
86k views

Get root access for copying files to /usr/share/…?

To be short, I want to copy a folder to a location /usr/share/screenlets/.... in Ubuntu 10.04 system. I tried by logging in as root from terminal giving su. I even changed my user account type to ...
32
votes
4answers
1k 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, DSA-2434-1)...
12
votes
4answers
26k views

How can I block ping requests with IPTables?

and stealth specific ports?
10
votes
2answers
11k views

Patch OpenSSL CVE-2014-0160 on ubuntu 12.04?

NO, this is not a duplicate of How to patch the Heartbleed bug (CVE-2014-0160) in OpenSSL?. So, read on. I am seeing conflicting information with respect to Ubuntu 12.04: The Heartbleed page claims ...
5
votes
2answers
2k views

Is Chromium in Ubuntu's repository safe to use since it's so out of date?

Is Ubuntu Chromium still safe to use since its so out of date?
14
votes
2answers
22k views

How do you set requirements (such as minimum length) on passwords?

Is there any way to set up minimum passcode requirements, such as a minimum length, requirement of mixed case alphanumerics and at least 1 symbol in the passcode, and enforce that at passcode changes?
6
votes
4answers
7k views

Is installing wine in Ubuntu safe? [duplicate]

Possible Duplicate: Risks/Disadvantages associated with Wine According to many articles like this one, it says that windows is more vulnerable to virus. I recently installed wine on my Ubuntu ...
5
votes
2answers
937 views

Precautions during SSH [duplicate]

Possible Duplicate: How can I audit users and access attempts to SSH on my server? I recently had to give away my Ubuntu 12.10 root password to one of my friends so that he could SSH into my ...
3
votes
3answers
4k views

Packet Sniffer found, what next?

After a download yesterday my computer crashed. I updated today and checked for rootkits. I found a packet sniffer eth0: PACKET SNIFFER(/sbin/dhclient[3966]) How can I remove this?
14
votes
3answers
3k views

Ubuntu vulnerable to malware sites?

I just browsed a site a while ago that was flagged as an "attack site" or has malware, but Firefox didn't warn before I went into it. Only when I opened a new tab with another page from the site did ...
13
votes
3answers
3k views

How do I call a dialog for authentication?

I am writing a gui program using wx module in python. In program whenever I am accessing a folder which requires root privilege then it asks password at terminal but I want to display the dialog to ...
3
votes
1answer
961 views

Security and Ubuntu [closed]

I have used Linux before (Ubuntu 13.04), but I have moved back to Windows after having compatibility issues with Windows programs ex. AutoCAD and ProEngineer Wildfire. However, I tried using Linux ...
13
votes
4answers
2k views

What is default password?

What is the difference between default and login? And what does Default Keyring mean? When I run some applications(Emphaty etc), Unlock Keyring window launched first, then it requires me password. ...