Content related to computer security., i.e. content about policies, mechanisms, etc. needed make sure data is not leaked or corrupted and services available in all circumstances.

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3
votes
1answer
145 views

What is the best way to restraint/secure a workstation?

I want to prevent users to copy on usb devices and some others actions. I was thinking of using polkit. Do you think it is a good solution or does someone know some alternatives ? EDIT: I also need ...
8
votes
1answer
3k views

Linux: LUKS and multiple hard drives

I have a Debian Linux system (amd64) installed on a RAID-1 system encrypted device (LVM on LUKS) and will have a RAID-6 of >=4 disks where I'll put my data (LUKS and maybe LVM). I think the basic ...
2
votes
0answers
121 views

Why do I get a different RSA fingerprint when multihopping using ProxyCommand

I'm using the following config to connect to multihop to the target host (gw2 and target have my public key stored in the authorized_keys file ; no netcat on all systems): Host gw1 HostName ...
2
votes
1answer
322 views

Securely Deleting A File In Ram

I'm running a live distro in ram. I need to write a password to a file. Later, I need to delete it securely. I don't know how live file systems work, so I'm unsure if I open the file for writing, ...
7
votes
5answers
1k views

Securing a Debian installation for general home usage

Debian comes with several harden packages, designed to make a computer more secure. My needs are very simple: word processing and Web browsing. I do not run any special servers, do not use SSH, ...
3
votes
1answer
1k views

Disabling Web camera

My Eee PC comes with a Web cam, which I never use. How can I ensure that it is effectively disabled, so that no software can use it?
1
vote
1answer
903 views

Any better alternative to chroot on an OpenVZ VPS?

Are there any better alternative to chroot environment? I'm thinking about running nginx on a jailed environment. BTW, I'm on OpenVZ VPS, so modifying the Kernel is a no-no. (I think that prevents ...
10
votes
1answer
647 views

Why aren't the Fedora GPG keys signed?

Fedora uses GPG-keys for signing RPM packages and ISO checksum files. They list the keys in use (including fingerprints) on a web page. The web page is delivered via https. For example the checksum ...
6
votes
2answers
728 views

Why did SDF switch from NetBSD to Linux?

I personally don't have much experience, but I was reading about SDF, and at one point the article mentions that SDF migrated to Linux in 1997, but due to the large number of malicious attacks it ...
2
votes
1answer
658 views

SELinux outbound access to other sites with restrictions

We have CentOS 6 configured with SELinux to host a number of websites. Unfortunately SELinux is preventing websites from accessing (outbound) sites, such as download.wordpress.com to update ...
13
votes
3answers
3k views

Can SSH passwords be sniffed out over Wi-Fi?

When you ssh, can the password you enter to connect, be intercepted if you're using untrusted public Wi-Fi (coffee shop, library, airport, etc).
3
votes
1answer
449 views

Does using epub2pdf pose a potential security risk? Is there an alternative?

epub2pdf is a fairly platform-independent program. Based on Java, it executes without a hitch on my machine, with no dependencies. However, strangely enough, the program requires an active internet ...
27
votes
2answers
68k views

What user should apache and PHP be running as? What permissions should /var/www files have?

I just spun up an Ubuntu 11.10 box and then ran apt-get install apache2 php5 to install apache2 and PHP 5 on the box. Now it is functioning as a "web server" and it loads the "It Works!" page. Now I'm ...
4
votes
2answers
3k views

Hardening debian?

So I have thought a bit about hardening a Debian squeeze file & VPN server lately. Right now, we've placed the machine behind a firewall only allowing SSH connections from LAN, set a strong root ...
-3
votes
4answers
500 views

Since Android has malware, does it mean no Unix is immune from malware?

Android has virus: Android.Counterclank, Android.Tonclank (seal info, back-door). Does it prove that FreeBSD, Solaris, Fedora, CentOS, ArchLinux, Ubuntu all is running and having similar ...
12
votes
4answers
2k views

Why do we need a firewall if no programs are running on your ports?

When I try to telnet to a port on a server, and if there is no program listening on that port telnet dies with a "Unable to connect ... " error. I understand that. But, why do we need a firewall if ...
5
votes
3answers
346 views

Preventing binary planting attacks in Linux

If a user account on a Linux machine is compromised, clearly, all files owned by that user are compromised. Unfortunately, if the compromised user also has sudo privileges, it seems that binary ...
14
votes
5answers
7k views

Shell Script mktemp, what's the best method to create temporary named pipe?

I'm aware its best to create temporary files with mktemp, but what about named pipes? I have an idea, I'm sure it would work, but I would really like an expert opinion. I prefer things to be as ...
1
vote
1answer
552 views

portsentry and IPTables on constant reboot, but not sure why

I have been doing some hardening on a new server [ centos 5.7 final ] i also have logwatch and seem to be getting these strange logs Commands Run: User root: /sbin/service portsentry restart ...
10
votes
2answers
2k views

Automatic security updates on Debian squeeze server

For a production Debian squeeze server, what are the best practices or recommendations for handling security updates? I have seen various articles on cron-apt, apticron, unattended-updates, apt cron ...
2
votes
1answer
108 views

Fedora15/Gnome3 - Exit elevated priviliges mode

While using Fedora 14 (Gnome2), Each time if I was doing some privileged task (ex - mounting a new hard drive), I would be prompted for password and then there would appear an icon (like keys) on the ...
5
votes
5answers
2k views

Why is it recommended to create a group and user for some applications?

Most of the time, when installing a program from source it is recommended to create a new user and a new group and give /usr/local/<myapp> the recently created user and group ownership. Why is ...
19
votes
3answers
6k views

Why does the 'bin' user need a login shell?

During an audit of /var/log/auth.log on one of my public webservers, I found this: Jan 10 03:38:11 Bucksnort sshd[3571]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 ...
8
votes
9answers
15k views

How do I write a test for system login?

I've written a Python CGI script that invokes bash commands, and it needs to test for a successful login on the host. How do I write a test for that? For example, could I create a bash script that ...
2
votes
1answer
116 views

What commands should be run when retiring a remotely hosted server?

I have a dedicated server from a friendly host located a substantial distance away from me, so the only access to the machine is SSH. It's a month to month deal, so I don't own the hardware. I'm ...
3
votes
1answer
261 views

sandbox tcpdump under OpenBSD?

From FreeBSD 9.0 tcpdump is sandboxed with Capsicum. Are there any solutions for sandboxing tcpdump under OpenBSD? Just want to secure a running: tcpdump -w output.pcap because it can be only used ...
11
votes
3answers
357 views

Prompt user on Linux security denial

Is it possible to make a Linux security module (eg. AppArmor, SELinux etc.) prompt the user, when an application wants to access classified files or folders (digital signatures, SSH keys, credit card ...
2
votes
1answer
600 views

UFW Limit does not appear to work

I have my ssh port changed to XXX. Then I did ufw limit XXX/tcp However, when I try to login, after 5/6 failed attempts I get thrown back to prompt, but I can try again. Is that supposed to be the ...
6
votes
4answers
4k views

SSH authentication: either SSH keys or one time password

I have an Ubuntu 10.04 Linux server that I normally ssh into (from my home machine) using ssh key authentication. However, sometimes I need to ssh remotely from potentially insecure machines (like ...
2
votes
3answers
3k views

Making sense of auth log

I am seeing some log enties that look like hacking attempts Type 1 Dec 26 03:09:01 ... CRON[9271]: pam_unix(cron:session): session closed for user root Dec 26 03:17:01 ... CRON[9308]: ...
10
votes
4answers
675 views

Good practice to use same SSH keypair on multiple machines?

I recently got a new laptop for work, and I was wondering whether it'd be good practice to keep using the same RSA keypair as I'm using on my old work laptop. I'd really like to not have to create ...
4
votes
3answers
353 views

Linux executable sandboxing?

I'm running a service that allows users to submit code which is compiled and executed on the server. At the moment I'm using Moe and while it works fine for C and C++ code, I've been having some ...
19
votes
6answers
22k views

How do I recursively shred an entire directory tree?

I have a directory tree that I would like to shred with the Linux 'shred' utility. Unfortunately, shred has no -R option for recursive shredding. How can I shred an entire directory tree ...
4
votes
2answers
787 views

How can I use Skype with lxc?

Under Scientific-linux? https://en.wikipedia.org/wiki/LXC I just want to separate Skype, because I don't trust it. We are using it only to call/chat with people, no file transfers!
10
votes
3answers
12k views

How can I track who SSH'es into my linux machine?

I'm running Ubuntu 10.04. Is there a way I can get a daily report of who has logged onto the box, what time, and even - this may be asking too much - a report of the commands they used? This is a ...
2
votes
1answer
901 views

Deny external SSH access to a user

Is it possible to deny access to a user (in my case www-data) from outside the network? Or possibly deny this: ssh www-data@example.com But allow this if already logged in: su www-data
3
votes
2answers
670 views

If you SSH into another computer, how to access other X displays?

This is a query based on personal use. A troll in our local network had downloaded Crikey, the key-event simulator. He used it to simulate events on other computers, leading to unwanted things. For ...
1
vote
1answer
199 views

How 'safe' is it to use new distributions of linux? [closed]

I hope this is the right place to ask this. I was looking at some new distros of linux that came out fairy recently and I really like their UI. I want to start using one of these but I'm a bit ...
2
votes
1answer
895 views

Debian + Nginx/Unicorn permissions

Is there a security risk in running a web server like Unicorn as root? The Nginx master process runs as root, the Nginx worker runs as the limited www-data user, but I can't set another user like ...
4
votes
2answers
609 views

Is it possible (and a good idea) to do `pw lock root` on FreeBSD?

I have set up sudo on my FreeBSD server. As I now never want to log in as root anymore, I was wondering whether I should do sudo pw lock root. My questions are: Is this possible, without forever ...
-1
votes
3answers
646 views

no root shell freely available sudoers policies

I want to prevent users who need escalated privileges from obtaining any kind of a root shell. However since there are many ways to attain this, and many non root commands ( like those found in ...
8
votes
2answers
155 views

Signing/Checksumming the kernel to prevent/detect manipulation

All my partitions are encrypted (/ and /home), but the /boot partition has to remain unencrypted and is open for manipulation. I was thinking about hashing the kernel on bootup and checking the result ...
28
votes
4answers
1k views

Execution of possibly harmful program on Linux

I'm writing a program that will test programs written by students. I'm afraid that I can't trust them and I need to make sure that it won't end up badly for the computer running it. I was thinking ...
5
votes
1answer
281 views

How can I find a Ubuntu package to use with Amazon EC2?

I'm looking to set up a new server on Amazon's EC2 and I wanted to use Ubuntu 11.04 is it is fairly new but not too new. I previously used 10.10 which I think is also very stable and time-tested. My ...
3
votes
3answers
356 views

Setting execution right to whole directory - is it good or bad idea?

I have a zip file containing lot of files and directories for a certain application which should be running on Linux. Some files needs to be set as executable, but the zip file format afaik does not ...
2
votes
1answer
2k views

Encrypt files using gpg (and them symetric encrypting the key) - is it a normal thing to do in the *nix world?

I read a lot of articles about using gpg to encrypt email, but I would like to use it to encrypt some files - mainly a bunch of *.isos. I'm going to describe what I thought I would do, so you can ...
1
vote
1answer
555 views

LoJack protection and recovery for Unix/GNU/Linux running systems?

The LoJack theft protection and recovery system looks very impressive, especially that they will find and return your computer for you, but the software is for Windows and OS X only. Is there an ...
3
votes
1answer
162 views

how to disallow user to change process group

Is it possible to restrict a process from changing it's process group? For example, user nobody seems to be able to call setpgid(0, 0) which sets process group of current process to pid of that ...
2
votes
2answers
328 views

How to deny rdesktop access to others?

Someone keeps trying to connect to my Ubuntu machine through remote desktop. Is there any way I can determine who it is, and permanently block access to my machine?
1
vote
1answer
1k views

How to find out that someone is using a Keylogger on the machine I am using?

HW/SW/whatever keyloggers are there. How to find out? E.x.: Regularly check the cable of the keyboard, because there could be HW keyloggers: http://i.imgur.com/TeMwo.jpg But what about other HW ...