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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1answer
624 views

Best practices for secure, separated virtualhost LAMP environment

What are the best practices for a Debian Squeeze + Grsecurity/PAX based system when multiple, and therefore insecure, websites must run on the same server? I mean how can I mitigate an attack, so that ...
3
votes
1answer
156 views

mounting volume protected against user access

I need to mount a directory in a way that prevents user accessing it. However I need to have access to all attributes (including permission) from root. Is following method safe or is there a way ...
12
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2answers
2k views

How to safely pass variables to root-enabled scripts?

This question is totally general and not only applicable to my situation, but... I have a small busybox appliance where I want a non-root user to be able to execute a particular script with root ...
8
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1answer
172 views

Does ssh-agent store my passphrase?

Is it possible to determine the passphrases of private keys added to ssh-agent? I'm thinking along the lines of someone with root privileges trying to find out my passphrase after I have added the ...
5
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4answers
1k views

How sudo/root-ness detection works

Programs that make changes system-wide require sudo unless I am already the root user. Now, the question is: how exactly does the system figure out that I am (not) root? Does it: Check to see if ...
5
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2answers
1k views

Can KWallet manage my ssh passwords?

I need a way to store some SSH passwords. Note that these are login passwords which I need to pass to ssh; key authentication is unfortunately not an option. I'd like to be able to have KWallet fill ...
2
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1answer
376 views

Debian unstable chroot security issues

This page describes how you can use the debootstrap utility to install a base Debian unstable/sid system on an existing Linux machine. The new install is accessible using chroot. When doing this, ...
2
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0answers
807 views

Security of xhost (local) and sudo xauthority forwarding

Context: launch a GUI application as a linux service. I considered making a headless daemon with a GUI front-end but there is too much code involved to do it now. This service must start on user ...
2
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1answer
759 views

root password changed automatically

I have my system on dual boot (win7 and RHEL 6). I have 2 user account on RHEL 6. A normal user and a root user. I put passwords of both accounts same. It was working fine from 5 6 days. Yesterday I ...
3
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4answers
3k views

File permission execute only

How can I set file to be executable only to other users but not readable/writable, the reason for this I'm executing something with my username but I don't want to give out the password. I tried : ...
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1answer
9k views

Why are the first 1024 ports restricted to the root user only?

This is more idle curiosity than anything else. A friend of mine asked me 'which port range is it that only root can use under Linux?' I told him 0-1024 were restricted. Then he asked my why it was so ...
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2answers
2k views

Is it safe to give out my SSH public key for work?

I currently work remotely for a number of organizations which need me to access their servers regularly for maintenance and upgrades. Is it safe for me to add my RSA public SSH key to the ...
11
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6answers
643 views

Which linux distro's package repositories are secure and which are not?

Most distro's I know have some kind of repository functionality where new packages could be downloaded after installation. Which distros do this in a secure way and which doesn't do this in a secure ...
4
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1answer
183 views

How do I know which files will be included in a linux kernel before I build it?

I am working on a project that includes building an old kernel version of linux. This is fine, but I still need to patch the kernel of all previously found security vulnerabilities based on CVEs. I ...
3
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3answers
2k views

How secure is Ubuntu in Virtualbox on Windows host?

I have the most recent version of Ubuntu in Virtualbox on Windows 7 host. How secure will that be? I mean if I get malware on windows how will that affect the Ubuntu system I am working on?
9
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2answers
1k views

How do I hide/anonymise/defend a computer when on hostile networks?

I connect to a lot of open networks when I'm pootling around. I'm fairly careful to VPN home for anything important but that's not really my boggle. The laptop runs several services (nfs, dev http ...
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2answers
311 views

Can I get infected in this case if I run a live cd?

I recently got rid of a nasty trojan on Windows and want to migrate to Linux(Ubuntu). I want to run a Live CD so that I can format an SD card to put my brand new firmware on my router and format the ...
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1answer
1k views

How to secure CentOS and FreeBSD by disabling USB ports and VGA output on-site?

Is it possible to disable USB ports and CDRom and VGA output in the Dell R310 from CentOS or FreeBSD (without BIOS)? A demo server is running in a customer test laboratory, where they can simply get ...
4
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6answers
458 views

Any program like `sudo` to gain root by having two users enter a password?

I run a server which is used by a group of individuals for e-mail, mailing lists, personal web homes etc. I thought about ways to provide root access for other members to allow them handling problems ...
8
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2answers
4k views

How come no core dump is create when an application has SUID set?

I setup my environment to create a core dump of everything that crashes, however when I run an program with SUID set on a different user than the executing user it doesn't create a core dump. Any ...
5
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1answer
617 views

Custom PAM modules and security considerations

I am writing my own PAM module that will be part of an application that I am developing, but I'm not sure exactly where to put it. My module basically does network-level authentication (with other ...
13
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2answers
2k views

How to avoid escape sequence attacks in terminals?

Reading the details of CVE-2009-4487 (which is about the danger of escape sequences in log files) I am a bit surprised. To quote CVE-2009-4487: nginx 0.7.64 writes data to a log file without ...
2
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2answers
152 views

How to create a new user without his own FS but with access to write to only one folder of user that creates him?

What are the command(s) to create a new user (not from su), give him the ability to write to only one folder which is some directory owned by an already existing user (the one that created him)? ...
7
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5answers
708 views

how do I wipe a server that I don't have physical access to?

I have a Godaddy dedicated server that I would like to cancel. Before I do that I'd like to do a clean format on the server to make sure that the next person who gets the server isn't able to undelete ...
6
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4answers
7k views

Fail2ban block with IPtables doesn't work on Debian Lenny. [moved ssh port]

I've recently decided to do some security maintenance. I saw my logs, and there were some tries against my SSH server. At first, I moved away the SSH port from the default 22. After it, I read ...
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3answers
2k views

How can I set that only root + a given user can shut down my pc?

If I'm using Ubuntu 11.04, how can I configure it such that that only two users can shut down/suspend/hibernate my PC: the root user and one regular user?
5
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4answers
2k views

Are there any GUI's for Linux that doesn't use X11?

Are there any GUI's for Linux that doesn't use X11? Since X has very poor security :O e.g.: Ubuntu, Fedora - what else are there? Goal: having a Desktop Environment without X. - what are the ...
2
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1answer
722 views

How to create a “jailed” environment for an application under Linux?

Using Ubuntu 11.04 as a Desktop OS, I want to reach "bigger security" with a "jailing" processes: VirtualBox, Google Chrome, Firefox, VLC, PDF/djvu reader, MP3 player, wine, pidgin, transmission, ...
7
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1answer
964 views

Is /dev/random data a psuedo-random AES cypher, and where does the entropy come from?

My current understanding of an entropy pool is that it gathers truly random bits of data at a slow rate. I'd like to know how Unix & Linux collect entropy, and how that entropy is used by ...
9
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4answers
6k views

Can someone sniff NFS over internet?

I want to connect to my home server from work using NFS. I tried sshfs but some people say it's not as reliable as NFS. I know sshfs traffic is encrypted. But what about NFS? Can someone sniff my ...
6
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2answers
977 views

Should I be backing up my SSH host keys?

In my automated backups, I'm not sure if I should be doing this. If the hard drive fails or if I wipe the hard disk and start over, what will be the effect of starting with a new SSH host key to my ...
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2answers
486 views

DNSSEC in the root zone? How to use it?

I'm using Fedora for desktop use and I: yum -y install caching-nameserver service named restart chkconfig --level 5 named on on it, and set the nameserver to 127.0.0.1. If I: dig google.com | grep ...
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1answer
4k views

What are the most secure cryptsetup parameters to create an Encrypted filesystem? [closed]

According to http://16s.us/Linux/dm-crypt.txt, it's better to use only dm-crypt, because LUKS leaves a trace. That's OK. But, what are the most secure cryptsetup parameters to use? E.g.: ...
2
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1answer
235 views

What flags are used to compile debian stable packages?

Ubuntu wiki states that its packages are compiled with secure flags and secure kernel options. I cannot find this information about debian. See https://wiki.ubuntu.com/CompilerFlags
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3answers
105 views

Does PGPDesktop supports OpenBSD or e.g. Fedora?

Does PGPDesktop support OpenBSD or e.g. Fedora, or can I only encrypt my whole hard drive when I use Windows?
2
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2answers
639 views

nmap output: what does “uptime” mean?

If I nmap a host, then it outputs an "Uptime" too. What does it mean, is it trustable? Does it gives correct times?
2
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1answer
399 views

A local, centralized, secure way to store FTP login data, including passwords

I want to be able to store the login details all of my remote FTP accounts in one place, securely. Then I'd like clients like autofs/curlftpfs, Filezilla, etc to use this one store of passwords. I'm ...
9
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1answer
681 views

Log every invocation of every SUID program?

I would like to have a log file that contains an entry for every time a user runs any suid program, containing the user name, the program and any command line arguments passed to it. Is there a ...
5
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1answer
385 views

SSH tunnel with VNC?

In theory: I have a low-power consuption machine: eee pc, ok. I need to run a virtualized windows xp on it. (Because of a windows-only program..) I need to reach it from a smartphone (Android). The ...
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1answer
198 views

Linux user security

When a user is created in Linux, their username can be seen publicly in the passwd file. Is there a hash set for that?
1
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1answer
221 views

fully disable the .desktop file function under GNOME?

http://www.geekzone.co.nz/foobar/6229 How can I fully disable the .desktop file function under GNOME?
1
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3answers
155 views

Tool to remove all non-package files on a system

If you want to keep for example a build or server system clean, it is very useful to be able to check that all files are present and accounted for by the package metadata. At work we have a very nice ...
3
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2answers
571 views

How to block outgoing connections from process/user on FreeBSD?

My server executes third party software which processes user submitted files. I want to block outgoing connections from my process. How can I do it in FreeBSD?
12
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7answers
5k views

What's the best way to format a HDD in Linux in order to leave no trace?

I'm running Debian and need a way to format the entire hdd in order to not leave any trace on it because I want to donate it to a friend. So what will be the best way in order to format it? If I ...
11
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4answers
843 views

How exactly do people “crack” Unix/Linux Systems?

No im not looking to become a cracker or something like that, but Im trying to figure out the process (more from a programming perspective). So im assuming (guessing) a cracker's main goal is to gain ...
7
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1answer
561 views

Opening port 80 but remain secure

I have a standard installation of Ubuntu 10.04, and have installed the LAMP stack so I can do some web development locally. On my router I have opened port 80 so I can develop with external services ...
4
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1answer
1k views

Disable random memory address generation in my programs

I'm reading "The art of exploitation" and would like to try some experiments, including reading from and writing to various memory address. I've created some simple programs and trying to overwrite ...
2
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4answers
2k views

Private VLAN's under Linux?

http://blog.ine.com/2008/07/14/private-vlans-revisited/ Has anyone tried private vlan's under Linux? Any experiences with them? My real question is does anybody have howtos regarding this?
4
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5answers
156 views

Hiding work in account with multiple users

I'm currently working on an assignment in a cluster programming class. The class has been given an account on the cluster, so we can ssh in and do our work. The problem is that the one account is ...
2
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1answer
235 views

How do I make a certain command sudo-only on Debian?

What user and group should I chown it to? All admins are in 'admins' group. How do I chmod it?