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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Encrypt directory on Linux

I need to create an encrypted directory (to be then filled with files and subdirectories) in a Linux ext4 filesystem, accessible to just one user. It should be: visible (just the root) from the non-...
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1answer
18 views

Unix winbind groupmap

i got Linux server (SLES 12) joined in Windows AD with winbind and samba services. I got unix group "mqm" and windows AD group "67uts-mq-admins". I want to map windows AD to unix group with "net ...
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Iptables restrict all, allow multiple specified users to destination port

This great answer tells me how to prohibit all users from connecting to remote host on specified (in this case 25) port, except one user: iptables -I OUTPUT -m owner ! --uid-owner postfix -m tcp -p ...
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2answers
79 views

Linux root access recovery by booting on the console

This is my first question so bear with me please. So I have a concept in mind that I can't quite grasp. Very recently I recovered a root password for a Debian server by booting into single user mode. ...
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1answer
31 views

I am facing huge attack of layer 7 on port 3306 can anyone help me?

I am facing huge attack of layer 7 on port 3306 can anyone help me? my iptables rules are good too 184 9568 REJECT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 ...
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something very strange happend to my linux [closed]

i would like to ask you about a thing which is related to Ubuntu's security. I have been using ubuntu for a long time but i has never happend to me before the thing is: 2 days ago when i was ...
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1answer
46 views

Executables in /usr/bin not showing for permissioned users [closed]

I installed xvfb-run using yum under root, and I can see the executable in /usr/bin with the permissions -rwxr-xr-x. When I login under a different usr which falls into the 'other' permissions, the ...
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1answer
13 views

Hash sum of partitions that haven't been mounted changes every time after a live usb run

I have a Live USB with puppy linux on it. Here's menu entry in Grub2 for Puppy: menuentry "Puppy Linux 6.0.5 tahrpup" { insmod ext2 search --no-floppy --fs-uuid --set=root 0641378e-...
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96 views

Taking a picture with a laptop webcam after entering an incorrect password

I'd like to set up my laptop so that if a wrong password is entered when the screen is locked, a picture is taken using the laptop's webcam. I examined xlock (from xlockmore package), but there is no ...
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30 views

Can't disable TLSv1 and RC4-SHA

I need to remove TLSv1 and RC4-SHA support in Centos 7. I have these lines in my ssl.conf SSLProtocol +TLSv1.2 +TLSv1.1 -TLSv1 SSLCompression off SSLHonorCipherOrder on SSLCipherSuite "ECDHE-ECDSA-...
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31 views

How to reboot a server with a LUKS encrypted partition

I have a CentOS 6 VM on which I used the following shell script for installing and configuring MongoDB to use a secondary LUKS (dm-crypt) encrypted disk for its database files: #!/bin/bash -e # Set ...
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11 views

removal of cleartext passwords from clogin.rc file of RANCID

We are trying to avoid the usage of cleartext passwords in .cloginrc file of RANCID by using CyberArk API which provide passwords ondemand . API is capable to made available passwords of accounts been ...
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1answer
50 views

Possible attack against VNC Server

Recently I started to have some problems with my Linux machine. So I have this Linux VPS machine with VNC server installed and I just connect to it by using VNC viewer. Recently the VNC server/...
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23 views

How does reboot run without root password on the console? Can I get this to happen with other programs? [duplicate]

I login at the graphical console terminal on basically stock RHEL Linux 6, and type reboot in the command window. The system reboots without being asked for a password eventhough I am not the root ...
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6 views

parsing audit logs of rootsh

We're using rootsh for auditing users privileged shells. This unfortunately means they want to push the problem of auditing up to infosec, but here in infosec, the logs are not very readable. E.g., ...
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1answer
41 views

How to turn off stack protector in linux kernel easily? [duplicate]

I wrote a simple module for the Linux Kernel and it has a stack buffer overflow vulnerability. I want to exploit the module, but I have to turn off the stack protector in the kernel first. How could I ...
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1answer
48 views

How can I make Linux as secure as possible? [closed]

I am relatively new to Linux, and I love it. With the rise of Windows 10 I am getting more concerned about my privacy and the risks of using an unsecured system. My question is three fold Which ...
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7 views

Git + Nginx - Is it safe to have https auth for cloning and pushing to repo, while remove any auth from gitweb block?

I have following nginx configuration on Ubuntu 14.04 to use together with git httpd backend and gitweb to anonymous browse of repo and push/clone with authentication. Is it safe to use such or I ...
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1answer
42 views

Debian Security Updates

If I am running an 'unsupported' version of Linux, which is based on Debian, is there any way that I can still get the updates from debian systems as they are released? OR am I stuck waiting on the ...
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1answer
101 views

Mediawiki support has been dropped in Debian stable (jessie). What's the alternative?

Yesterday, Debian removed Mediawiki from its stable distribution: Removed packages ---------------- The following packages were removed due to circumstances beyond our control: +--------------------...
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1answer
50 views

Remote docker over ssh tunnel

I have been testing docker. Due to strict firewall policy that blocks all ports except the ones necessary, I bind my docker clients to local ports and use ssh tunnels to access them remotely for the ...
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1answer
22 views

How to extract RSA keys from Apache

I am testing some old vulnerabilities related to SSL/TLS, and would like to know how to extract temporary RSA keys from Apache. The particular vulnerability I am testing is the FREAK attack. I ...
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0answers
16 views

What are the most restrictive external firewall / DNS listening port settings I can have for my DNS server (internal clients only)

This question relates specifically to hardening the configuration of DNS, firewalls and at the limit, ntp. (not proxys, http access,vpn's or other services). This is about the externally-facing side ...
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9 views

Send new login & logout logs to a database

I want to know how to send new login and logout logs to a database. I know that last command outputs the "lasts" login info. But, I found the following problems? How to filter to only get new logs? ...
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Looking for a tool similar to the Security Advisor plugin for WHM that can run on CentOS 7 without WHM

The startup I'm working at is setting up some new CentOS 7 servers that will host a mobile application, and some of the data is sensitive, thus, the servers need to be secured to the best of our ...
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1answer
47 views

How does chsh prevent users from changing another user's shell?

I know chsh is used to change a user's login shell by modifying /etc/passwd. So, in principle anyone could run this command and change another user's default shell but that is not allowed. How is ...
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1answer
27 views

Globally writable files and user-based process jailing

I want to be able to generically pick a certain executable (potentially malicious) x and run it (from an admin account) with write access restricted to certain directories (dynamically deduced) "${...
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1answer
48 views

How is the authenticity of Debian packages guaranteed?

What security systems and processes are in place to prevent malicious third parties from hacking/compromising the security of code in the Debian mirrors, or to verify that the packages we get are in ...
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1answer
20 views

Add a second authentication to user log in

trap '' 2 code=`oathtool --base32 --totp "xxxxxxxxxxxx"` echo -n Enter Code: read -s password echo "" if [ "$password" == "$code" ]; then echo "You are allowed in" else exit fi trap ...
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1answer
33 views

Suspicious traffic in nethogs on fresh install

Earlier today google said that unusual traffic was emanating from my computer and gave me a captcha. I got curious and installed nethogs. Everything appears normal except for an unknown program ...
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1answer
29 views

2 factor login for gui and ssh imposes verification for sudo use

tldr: how can I make it so I don't have to use a verification code to sudo? Hello, I followed this guide on how to setup 2 factor login for my debian install. I have it so when you try to login ...
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3answers
47 views

Does it make sudo more secure when indexing all commands by their SHA-2 checksums?

I'm asking myself whether system security substantially increases when I generate a security policy, i.e. sudoers file which contains one or more Cmnd_Alias definitions that enumerate all executable ...
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pam su authentication with RSA token [closed]

We are implementing RSA token authentication in our company and management decide su - should ask for RSA token passcode for individual (listed users) user. So no-one is going to get root password: it'...
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0answers
61 views

Exploit in bash script parameter possible?

I want to pass an e-mail address from a web form to a bash script. I'm using the following regex: /[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}/ Is this sufficient? Or could one embed an exploit?...
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0answers
10 views

openvassd hanging

I have a problem with openvassd hanging while starting: connect(6, {sa_family=AF_LOCAL, sun_path="/tmp/redis.sock"}, 110) = 0 fcntl64(6, F_GETFL) = 0x802 (flags O_RDWR|O_NONBLOCK) ...
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Greenbone/OpenVAS not starting tasks after reboot

I have Greenbone and OpenVAS installed on a Fedora machine. Configuration was OK and everything was working fine. After a reboot every attempt to start a task results in the browser waiting forever ...
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2answers
29 views

ptrace suid binaries after privilege is dropped

I understand that we probably cannot do ptrace on suid binaries. However, I'm wondering why we cannot do ptrace after the binary drops its previlege to uid instead of euid. For example, in the binary ...
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1answer
38 views

Are NetBSD provide digital signatures for official ISO images and binary packages?

I just install NetBSD in from ISO image inside VirtualBox. Official source ISO media contains only MD5/SHA512 sums. Similarly pkg_add binary packag repository contains only SHA512 sums. Both FTP ...
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1answer
40 views

groupadd -p Not Recommended?

I have a question about groupadd, specifically with password (-p). It says it is not recommended, "This option is not recommended because the password (or encrypted password) will be visible by users ...
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2answers
60 views

Safe execution of cat command without executing arbitrary code

I do this little file based on a combination of hexadecimal, that can broke cat and the terminal showing the file with cat, reset does not worked anymore, it is maybe putting cat in a kind of loop? ...
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1answer
31 views

linux periodic system check script or utility [duplicate]

Is there any commonly used shell script or utility to periodically check Linux file systems for changes, such as permission or ownership changes of configuration files. I am thinking of something ...
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1answer
33 views

Is there an additional option to display hidden command on the terminal?

Copy and pasting from a website to the terminal is very harmful , there are an example here You past the following line :ls /some/thing/much/too/long/to/type/ , by pressing Enter the following ...
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1answer
31 views

How to limit connections to OpenSSH server to using private keys necessarily with passphrase?

Is there any way to configure OpenSSH (/etc/ssh/sshd_config) server to allow private keys necessarily with passphrase?
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1answer
13 views

Standard Package updates of selinux-policy-*

I am wondering if after installing an update of a selinux-policy-* package you are using, do you need to reset all the labels in the system (i.e. fixfiles onboot) in order to keep the policy effective?...
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1answer
123 views

Executing commands in an elevated bash process by writing to the standard input of its parent script process

I have a simple bash script bash.sh that starts another bash instance using pkexec. #!/bin/bash bash -c 'pkexec bash' When executed this shows a prompt for the user to enter their password. The ...
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2answers
40 views

Why should not I update to most recent kernel immediately after release [closed]

Question intended for system administrators. Consider system running a old but working kernel and all the required functionality is available. (Ubuntu 12.04 LTS specifically with kernel 3.2) Then a ...
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2answers
91 views

Malicious processes open connections to China

I recently started migrating some of my company's servers to Google's compute engine. Among other things I set up a 2-node elasticsearch cluster. Today I run top command on one of the nodes and I ...
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2answers
33 views

History -c, where all the erased histories have been saved and in which directories though?

Usually, when i used (root@example ~ # history )and it displayed a lot of commands which had been entered before. So, my question is : when i enter "history -c" is to delete all the history at the ...
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1answer
47 views

AIX : /etc/security/limits file Parameters [closed]

Can anybody please explain about following parameters found /etc/security/limits file default: fsize = 2097151 core = 2097151 cpu = -1 data = 262144 rss = 65536 stack = 65536 ...
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1answer
52 views

How do I make sure the iptables is closed?

I want to disable iptables completely. I followed the instruction like /etc/init.d/iptables close it said there No such file or directory [root@dataapp02 tmp]# service iptables stop Redirecting ...