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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2answers
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Encrypted FileSystem in VirtualBox

I'm looking for any information regarding how secure an encrypted Linux file system is when contained in a VirtualBox virtual drive on a Windows host? Specifically I'm looking for answers to the ...
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1answer
27 views

Monitoring tool without web interface

I need to monitor a Linux server. I'm searching for a monitoring tool able to store system information (CPU, RAM disks usage, Apache and Postfix status, etc.) throughout the day and send an email ...
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2answers
50 views

Per user tmpfs directories

Using the shared /tmp directory is known to have lead to many security vulnerabilities when predictable filenames have been used. And randomly generated names aren't really nice looking. I am ...
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0answers
13 views

Is user/filesystem access separation of services enough to have well secured data of services?

I'm about to publish some of my projects. So, I'm gonna to re-install my VPS and do it properly. I'll have running on it Apache server(websites are made using Ruby and Python), databases. I'll also ...
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1answer
31 views

How do I run a program without network access? [duplicate]

I am making a program that scrapes information from some web services. I want to test how my program reacts when it can't reach the web service, like if the web service is down or if the local ...
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1answer
37 views

unknown command “vftovp” in linux command history [ Is my linux box compromised? ]

I have Slackware linux system configured with ssh remote access. While observing the command history, I discovered that there is one unknown command executed from my linux box "vftovp". I certainly ...
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0answers
19 views

why do we have same chains in different tables of “iptables firewall” in linux?

why do we have same chains in different tables of "iptables firewall"? Like for example: we have "output" chain in filter table, nat table & mangle table.
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0answers
40 views

Is there a technical reason why ssh-agent lacks a sudo-like inactivity/idle timeout feature?

There are some brief discussions about the existing ssh-agent -t feature at [1], and there was a post as far back as 2001 on debian-devel [2] wishing for an inactivity timeout feature. There's a ...
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0answers
17 views

Are External API's secure? [closed]

I'm new to java. So please someone explain me if we can use external API's in my work? Are they secure to use?
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4answers
45 views

Can administrating task of 'root' be divided to the several of “more powerful” users?

Unlike root (which is able to do everything) is it possible to have multiple administrators assigned to manage only part of a system? For example, one system could have 3 administrators: ...
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1answer
25 views

Compare Linux configuration with default

My system fails to upgrade. I suspect it was breached. Is there a way to compare system configuration to default version that should be at this date and kernel version? My current system is Debian, ...
5
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1answer
34 views

Find out which kernel source files were used when kernel was compiled

I am compiling the Linux kernel for my specific hardware and I only select the drivers/options which I really need. This is in contrast to a typical distribution kernel, where they compile almost ...
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1answer
41 views

How to know su password

You already know my question. I don't have su authority. So I want to know su password. I really(x100) don't know how to find it. I tried change direction(/etc/pam.d/su) and tried to delete auth ...
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2answers
63 views

How to protect against data leak?

We have a few workstations that have access to a network share with all our company files. This is correct, because users may need to use them. However our boss is concerned that someone (upon ...
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4answers
1k views

How to retrieve IP addresses of possible ssh attackers?

I've just cat /var/log/auth.log log and see, that there are many | grep "Failed password for" records. However, there are two possible record types - for valid / invalid user. It complicates my ...
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1answer
26 views

Is it possible to scan a website for repeated images?

Is it possible to determine how many times a website is using an image (specifically one that is hosted on the domain), and on what pages? Is there a command line tool, for example, that scans every ...
2
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1answer
32 views

Where do my keypresses go ?

Scenario (Ubuntu 14.04.2) : I wake Ubuntu from suspend. I know (from past experience) that it only takes 2 or 3 seconds for the lock screen to become available. My monitor, however, takes longer - ...
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1answer
35 views

Firefox in Docker, failed in isolation

While experimenting with docker, I realized I can run a browser in a container for improved security. I managed to start with a clean Docker Fedora, in which I installed the openssh-daemon package. ...
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0answers
51 views

SSH server listening on multiple ports with passwordless access not allowing connections to second port

I have my Synology NAS running an SSH server listening on the default port 22 and I set up passwordless authentication with a public/private key and a passphrase: From sshd_config: ...
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0answers
33 views

Persistent SSH port forward without public keys

Problem I haven't found a solution to run an SSH port forward in a reliable and persistent fashion, when the server you are connecting to does not support public-key authentication. Question What ...
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1answer
37 views

Is it possible to mount a file with different ownership/permissions?

I have been experimenting with privilege escalation using the mount command and would like to know if it is possible to create a suid file owned by root without having access to any external device. ...
0
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1answer
41 views

FreeBSD 10: Do I need jails?

I'm in the process of setting up a FreeBSD 10 server with just some services on a KVM server: NGINX webserver w PHP-FPM 2 domains, 3 subdomains Mailserver 3 Email addresses MySQL (or other) ...
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1answer
19 views

FreeBSD 10 and ZFS: Methods for encrypting files

I'm in the process of setting up a FreeBSD 10 server on a KVM vserver. I'm really new to FreeBSD in general (coming from Debian Linux). I installed the system choosing ZFS with encrypted root volume ...
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0answers
50 views

md5 password hash

I'm looking to create a md5 hash to use in /etc/shadow. Someone suggested using grub-crypt. Every time I put the same password in I get a different hash. [root@endpoint ~]# grub-crypt --md5 Password: ...
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4answers
63 views

can a super user steal passwords from other users with keylogging?

First, before I get answers containing information that I already know, yes, I'm aware that the superuser can reset passwords, and yes, I know that the superuser can log in as other users without ...
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2answers
35 views

Is this an argument that Linux security is not impenetrable?

From what I understand, the biggest and probably only line of defense against unauthorized software (viruses and worms) from being installed on the system is to simply not allow it unless an admin ...
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3answers
54 views

Is linux secure? [duplicate]

Is linux free from almost all security vulnerabilities when compared with windows? If there are so, can i install any patches to fix them? Thanks in advance.
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1answer
386 views

Linux Server Hacked

I received e-mails from Google saying that my websites are hacked. This is the e-mail. Dear site owner or webmaster of domain.com (I received this email for my other domains too), We recently ...
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1answer
17 views

Can I use the sudoers function without enabling the suid bit?

I mounted all my FS with nosuid option and removed the suid/sgid bit from all my files. The question: It looks like I breaked sudo. It doesn't work anymore, no matter what I try to set in ...
2
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1answer
124 views

Why is “nodev” in /etc/fstab so important? How can character devices be used for hacking?

I am learning about linux security and struggling to understand why a USB stick with a character device on it is potentially dangerous. If I have a USB stick with a bash executable that has setuid ...
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3answers
480 views

How do I explicitly and safely force the use of a built-in command in bash

There's a similar question that deals with the 'wrapping' scenario, where you want to replace for example cd with a command that calls the builtin cd. However, in light of shellshock et al and ...
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2answers
36 views

Chroot user exit jail [duplicate]

I am using OpenSSH chrootdirectory feature to give access to a user via ssh. Can this user exit the jail and return to the normal OS environment? Maybe with su?
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1answer
50 views

CRON session entries in logs

I'm having this in my RaspberryPi /var/log file Feb 26 21:17:01 raspberrypi CRON[15182]: pam_unix(cron:session): session opened for user root by (uid=0) Feb 26 21:17:01 raspberrypi CRON[15182]: ...
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2answers
45 views

How to get a grsecurity kernel on Debian Wheezy using the linux-patch-grsecurity2 package?

There is a package linux-patch-grsecurity2. But it seems to be lacking documentation. How to make use of linux-patch-grsecurity2 to get a grsecurity enabled kernel?
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1answer
29 views

Different password for login and sudo - security concerns

I'm planning to follow the steps described in this answer to have a different password to log in and sudo. The reason is that I want a high security password to access my account or unblock the ...
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1answer
46 views

Throttle accounts after failed SSH login attempts

I have to set up a server that will allow remote logins. Obviously security is an issue. In this first pass we are discussing:- Locking a person for 15 minutes if they fail to login correctly three ...
2
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1answer
32 views

How to set up users, ownership and permissions across local and remote servers?

I've been learning the Linux OS over the last year or so and I am still very confused on how permissions vary from different configurations. I am trying to set up my local development environment and ...
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2answers
23 views

Protected archive (7z, RAR, Zip) open at a specific time

Are there any compression tools that are unopenable or password-protected until a specific time, at when the security is then lifted? Literally an enforced: "Do not open until --/--/----"
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3answers
107 views

how to set up permissions of “download” dir to prevent execution of exploit program

There is a host with a local service that receives data from a remote location (via e.g. http) and saves it locally under /var/log/data/ in some mydir. $ ls -al /var/log/data drwxr-sr-x+ 4 root ...
2
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1answer
65 views

Is it possible to access any file or dir within a non-accessible directory? [duplicate]

Say I set my home /home/john directory as not readable for any other user. But I've forgotten to do so with some files within that directory, say ./.bashrc or ./Downloads/Presentation.ppt. Now, if ...
28
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7answers
5k views

My server is constantly being attacked [closed]

I am fairly new to the system administration world. I've been working on an application recently and when I check my application server logs, I constantly get various IP addresses trying to ssh into ...
1
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1answer
34 views

How to update all Debian packages from source code?

For building packages from source code, there is apt-get source --compile pkg-name. But for it to work, one has to run apt-get build-dep pkg-name beforehand, which downloads binary packages. Is it ...
4
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1answer
37 views

How can I test whether Chromium is running inside sandbox

I am using Chromium browser on Debian Wheezy. I read that Chromium is using sandbox to isolate its processes from the rest of the system and thus to increase security. How can I verify that Chromium ...
10
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2answers
177 views

A consistent and safe approach to passwordless accounts with SSH

I must admit that I like servers without passwords in some cases. A typical server is vulnerable to anyone who has physical access to it. So in some cases it is practical to lock it physically and ...
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0answers
15 views

Returning from a sleep the desktop displays shortly (before entering password), privacy issue

OS: Linux mint 17.1 Cinnamon 64-bit Cinnamon version 2.4.6 Intel Celeron: 900 @ 2.20Ghzx1 Memory 2 Gb Graphics Card: Intel Mobile 4 series integrated When I return to my computer after it has been ...
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2answers
70 views

How to prevent the messages about REMOTE HOST IDENTIFICATION HAS CHANGED

Is it possible to prevent the following message about: ( REMOTE HOST IDENTIFICATION HAS CHANGED ) When using only this connection syntax ssh xxx.xxx.xxx.xxx example of warning message: ssh ...
1
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1answer
54 views

How to force rpm and yum to fail if a GPG signature is missing or cannot otherwise be verified?

How can I force rpm and yum to fail if a GPG signature is missing from a package or otherwise cannot be verified due to a missing key? For the example below, assume the RPM has been signed but the key ...
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1answer
82 views

Reason why ssh RSA key would change?

Today I went to connect t my Centos 7 box via ssh and my sftp client and both indicated that the server RSA key finger print had changed. I've checked all my logs for suspicious activity but don't ...
2
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2answers
898 views

Ghost Vulnerability On Linux

It came to our notice that glibc needs to be upgraded from 2.2 to the latest version as per the release 5/6/7. My Question is that do I need to reboot the system, because we are having more then ...
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2answers
100 views

how to record all who that login to my linux machines and records them

I installed the package audit on my linux red-hat 6.x machine in order to view the recored of each user that log to my linux machine yum install audit kit installation from: ...