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

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28
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8answers
9k views

How 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 ...
1
vote
1answer
60 views

Confused about the security of ubuntu (Linux)

Assume I have a laptop with ubuntu installed and two users abc and root. Both users are password protected. It is possible to reset root password using live CD or USB using chroot which would mean ...
1
vote
0answers
507 views

SSH connection failing since I changed server port number

Yesterday I changed the default ports on the server from 22 to 1993 then restarted but now I can't connect at all. I used ssh -i keyname.pem ubuntu@remotehost to connect then sudo vi ...
1
vote
1answer
43 views

Is it possible to setup a root like user for global read only access?

I'm hoping to give a security scanner a user that can read everything but not change or execute anything. Is this possible and if so how?
1
vote
0answers
17 views

How are security updates classified into low/med/high?

When an update becomes available for a particular piece of software, if I run aptitude changelog <name> I will see urgency as either low, medium or high. How is it decided which ...
4
votes
1answer
2k views

Did these log entries record an intrusion to the server?

Here are log entries I found in auth.log. What does + ??? mean? And was there an unauthorized access? Feb 11 07:48:32 tts-server su[31265]: Successful su for www-data by root Feb 11 07:48:32 ...
0
votes
0answers
26 views

How do you set up a systemwide read only user for a security scanner

I'm hoping to play with STEALTH https://apps.ubuntu.com/cat/applications/precise/stealth/ It suggests the creation of a read only access user that the integrity scanner can use to access its target ...
-2
votes
3answers
791 views

Is this a viable legitimate way to circumvent NSA spying on me? [closed]

If I set up my own email server in my basement using Ubuntu along with my own domain, own SMTP server, hosted the emails in my machine, ran a pretty wicked good firewall, would that circumvent spying ...
19
votes
3answers
1k views

What is the “Free software only” option when installing Ubuntu?

When installing Ubuntu, you get a Free software only option. Does that Free software only option mean Free as in beer or Free as in freedom? When I say free as in freedom, I mean FSF type of ...
0
votes
1answer
40 views

Limit privileges for download folder

In Windows, I was able to use the ICACLS utility to set files/folders with a lower integrity, in order to keep them from modifying higher-integrity locations. I'd like to do something like that with ...
1
vote
2answers
423 views

How to protect from cloning?

I have no experience using Ubuntu before I'm doing a point of sale project for a restaurant which will run in local Lan (offline not online). I will setup one mini PC as an Ubuntu web server. and my ...
0
votes
1answer
528 views

Alternative Open Source software to GFI end point security

What are the GUI open source alternatives To GFI end point security for Windows? knowing that i'm using Ubuntu 12.04 64bit Thanks in advance...
1
vote
1answer
34 views

How to clean data when wiping/reinstalling a compromised server?

I have a server that has been compromised, where the logs have been blown out and I have neither the ability nor the time to discover what actual pieces of the system were modified. The server was ...
0
votes
0answers
27 views

Is this a bug or normal (mis) behavior?

When I sudo-rebooted from the top-right menu, after Unity closed I was taken to an open tty, where I saw my login password in plaintext where I had typed it in earlier. In Ubuntu-bug, a specific ...
2
votes
0answers
28 views

What is the difference between security.ubuntu.com and archive.ubuntu.com? [duplicate]

The various releases have a -security channel in archive.ubuntu.com. How does that channel differ from the security.ubuntu.com? If I have to set up a local mirror, how does security.ubuntu.com come ...
60
votes
3answers
8k 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?
14
votes
6answers
4k views

Does spyware exist for ubuntu?

Someone I know said he had put spyware on my computer. Is he talking crap? I've been using Ubuntu 12.04 for nearly 3 years now and I've never seen any type of spyware, remote keyloggers or RATS ...
43
votes
6answers
17k 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. ...
7
votes
1answer
7k views

How to enable auto security update in Ubuntu 12.04 Server [duplicate]

When I installed the Ubuntu 12.04 Server in my VM, I chose to manually update security. My question is how can I enable it again? I know there are other packages that do auto update, but I'm just ...
0
votes
1answer
88 views

How can I make my WiFi hotspot secure?

I just created a wifi hotspot with an adaptor, and it says that it uses WEP security. I may be mistaken, but isn't WEP security not really secure? How can I make it more secure, such as WPA or ...
0
votes
0answers
91 views

Help recovering from a hack and a malware warning

On Thursday (2014/7/24) morning I discovered that one of my Ubuntu systems was hacked. I believe it may have been the malware NetWire. I was able to see some traffic from the internet directed at ...
2
votes
1answer
376 views

Why is root the owner of my Desktop in Ubuntu 14.04?

When I am in my home folder there is a padlock on my Desktop icon. In properties there is written that root is the owner of Desktop and consequently I can't put anything on my Desktop. I have ...
8
votes
2answers
5k views

Google Authenticator for Desktop (lightdm or gdm plugin)

There has a been a similar question, but that's not exactly what I want. I'd like to know if there is a plugin, or add-on, for lightdm or gdm that allows me to authenticate using my password AND ...
-1
votes
2answers
53 views

Security updates for old-releases

I know that I should upgrade to a newer supported Ubuntu version if possible, but: if you have no possibility to upgrade (for reasons not important here) you have to use the old-releases archive from ...
0
votes
1answer
37 views

Ubuntu 13.10 end of support

13.10 ends support today, I want to do a clean install of 14.04.1,but it arrives next week,is it highly risk to wait fot 14.04.1 one week with 13.10 no supported? Thanks.
2
votes
6answers
6k views

How do I encrypt/decrypt file within gedit?

In the previous version of Ubuntu (eg: maverick, natty), I used to do a: sudo apt-get install gedit-plugins seahorse to have the ability to encrypt/decrypt file within Gedit after enabling the ...
0
votes
1answer
39 views

Possibility that ubuntu machine infected by FTP malware

I know that this question might be duplicated but here is what happened. Our web server got attack by injecting the spam links into server script file (Web server running ...
0
votes
1answer
155 views

Setting up a secure mail server?

I am looking all over for a guide to setting up a secure mail server to be used with PHP and Apache. Can someone point me to a guide to do just that. I would like to have my own email ...
1
vote
0answers
35 views

How to prevent accidental unlocking?

I have a machine at work running tmux and xmonad that I lock with slock. I frequently need to ssh into it from a remote location, and, based on testing this in person, accidentally killing the slock ...
13
votes
3answers
35k 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 ...
1
vote
1answer
28 views

Moving away from ROOT user

I've recently been asked to help out a friend with some server and website issues they have been having, nothing major really. However I found out that since the day they got their VPS everything, ...
5
votes
2answers
3k views

Disable interactive SSH at user-level

I connect to a server I don't control via SSH. I use public key access and don't need to be able to connect with a keyboard-interactive password. I would like to disable keyboard-interactive access ...
1
vote
2answers
1k views

Should I be worried about a possible threat?

I recently installed Ubuntu 12.10. I use Clamav and have scanned my system regularly for infections. Today it picked up a potential threat ...
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 ...
23
votes
6answers
2k views

How can I confirm that the binaries in my Ubuntu are from the source code it should be from?

Like 99% of users, I install Ubuntu from ready-made binaries. How can I verify myself that those binaries are in fact from the original source code from Ubuntu? It would be good to verify that ...
1
vote
1answer
57 views

Security bug when switching user account

I face the following security issue on Ubuntu 12.04, Classic desktop. There we have 6 user accounts on the machine. One user logs on. Ok. Then a second user is using the User switcher logs in as well. ...
3
votes
2answers
45 views

is there some sort of all-purpose logging tool I can download as a package?

As in, a tool that will give me easy to read logging information all in one convenient place, divvied up into categories. Logs for say, ssh daemon, user logins/logouts and other activity, installed ...
15
votes
2answers
24k 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 ...
1
vote
0answers
49 views

install ubuntu on a hardware AES encrypted flash drive

I couldn't find the answer to my question after hours of search. I hope someone can help me out. I would like to install ubuntu on a flash drive. I followed to standard instructions for installing ...
0
votes
4answers
3k views

fail2ban or denyhosts to block invalid username login attempts

Is there a way to automatically block IP address when a user tries to login as any invalid username? I already have: [ssh] enabled = true port = ssh filter = sshd logpath = /var/log/auth.log ...
0
votes
1answer
137 views

Restrict user access to /proc and /sys

I have one big problem: setfacl does not seem to work for /proc and /sys, but I would like to restrict one specific users rights and I do not find it acceptable for that user to read stuff like ...
9
votes
2answers
6k views

What does “pts/” in the output of w mean?

When I run w - to see who is logged on and what they are doing, i see this: USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT user tty7 :0 08:14 10:32m ...
78
votes
8answers
43k 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 ...
2
votes
1answer
107 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? ...
0
votes
0answers
16 views

Are Ubuntu upgrades signed or encrypted?

When you download updates from the standard Software Updater (which I'm assuming is just a graphical front-end for apt), are these updates signed or encrypted between the server and the user, or are ...
0
votes
0answers
20 views

Want to know how how secure my system is with current settings

My system is at kernel 3.15.2 Mainline. I have Enabled the firewall with all ports closed. I have very strong passwords set for BIOS, Drive Encryption, and login SSH is Disabled. I have installed ...
2
votes
1answer
4k views

How to use rsync via ssh with rsa key passphrases?

How can I use rsync with passphrases? All googled "solutions" i found use passphrase-less keys which seems no real option. i am runnning 2 ubuntu servers 12.04.2 LTS.
0
votes
2answers
127 views

How to store network-manager settings in home

I'm using Ubuntu 14.04 with the network-manager. It stores all Information about wireless networks, VPNs, ... in /etc/NetworkManager/system-connections and I was just wondering why... I thought the ...
82
votes
18answers
19k 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. ...
0
votes
0answers
17 views

are ubuntu software center mirrors safe? [duplicate]

Could the admin of a mirror server/ isp attach a trojan into or fake a package? It's all my question. This sentence is just spam. You don't need to read. Why it is difficult to post a question here. ...