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
129 views

How can I ssh to a remote server with an automated password and no key?

I have a remote server. I planned to use public keys to connect over ssh without typing the password but the remote system rejects public key authentication. So what is the best way to do it? What ...
2
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1answer
18 views

Pin Lock Screen

Is there a way to replace password lock screen in Linux (Mint Debian Edition) with a pin lock screen? Like the one found in Windows 8 for example. It's annoying/inconvenient to have to input 16 ...
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2answers
46 views

Secure the content of a hard disk

I have to prepare a computer to give away, and I do not know who is going to use it. The computer has Debian installed, and the HDD is entirely encrypted. All users have their storage on the server. I ...
1
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1answer
626 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 ...
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1answer
358 views

Make bluetooth device invisible / disable incoming pairing

I am using the bluez package for my bluetooth usb dongle on ubuntu server. I want to be able to initiate bluetooth connection from the dongle to a device, however a device itself shall not be able to ...
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2answers
30 views

Locked out of SSH on LAMP server but have SFTP access

I made a mistake in /etc/sshd_config so have locked myself out of my remotely hosted server running Centos 6. It's running Apache and I have FTP access to /var/www and I know the root password. To ...
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2answers
32 views

How to set up a global interval between SSH log in attempts?

I would like to make it impossible to make more than a single remote log-in attempt in a number of seconds regardless the client IP address (except some trusted white-listed addresses perhaps). So ...
2
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0answers
44 views

A window asking me to enter my ssh passphrase is popping up randomly. Why?

I'm on Ubuntu 14.04. For a few weeks now a small window keeps popping up randomly, grabbing my keyboard and asking me to enter the passphrase for my ssh key. The Window's title says "OpenSSH", and it ...
18
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4answers
16k views

What is the point of sshd “UseDNS” option?

I know what it does, but i don't know why. What attack(s) does it prevent ? Is it relevant for all kind of authentication methods ? (hostbased, password, publickey, keyboard-interactive ...)
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1answer
712 views

SSL handshake failure with Shibboleth

I am using Shibboleth for single user authentication and it needs a ssl configuration which facilitates the user authentication process. Before it was working fine but now I am facing a SSL handshake ...
2
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2answers
73 views

Random named file in home directory, possibly hacked?

I am running Fedora 20, and today I found a file that looks highly suspicious in my home directory. The name of the file appears to be a base64 encoded string, but doesn't decode to anything ...
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3answers
68 views

Possible corrupt passwd file

I did a recovery of the server and reset the root password to a new one because for some reason, the original was not being recognised. It still is refusing to accept the password in ssh for root. ...
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7answers
11k 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 ...
0
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1answer
39 views

Faillog - unsuccessful login count in Motd

I wish to include a count of failed login attempts whenever a user logs in. I've created: /usr/local/bin/dynmotd which contains #!/bin/bash FAILLOG=`faillog -u` echo -e " $FAILLOG " and ...
8
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1answer
67 views

What makes systemd-nspawn still “unsuitable for secure container setups”?

This is stated in the man page for systemd-nspawn Note that even though these security precautions are taken systemd-nspawn is not suitable for secure container setups. Many of the security ...
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1answer
58 views

Create ssh root password

For some reason, after a plesk update, I can no longer login to ssh as root using my old password. I have tried to create a user with: /bin/bash & /bin/bash (chrooted) in plesk Which lets me ...
2
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0answers
55 views

Cannot connect to ssh server

I am having trouble connecting to my ssh server. It responds with a lengthy error message about no network etc. but it is the last message that concerns me: Sometimes, such troubles can be caused ...
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2answers
48 views

Reject ssh connections made from proxies

I was seeing this question which was concerned with blocking access to the users who do not belong to a particular region. I am sure that blocking is possible but I see there is a workaround to this. ...
2
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1answer
496 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!
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0answers
18 views

Configure samba for encrypted transmissions

I tried to turn on encrypted transmission from the documentation with smb encrypt = mandatory Now, I cannot connect or even see the computers on the network. If I try to manually connect with nemo ...
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0answers
11 views

Ubuntu Firewall Configuration Just for Browsing and E-Mailing [duplicate]

Is it possible to configure UFW just for browsing using firefox, e-mailing using thunderbird and updating the system? How should I proceed? I would like to use the UFW directly without any GUI.
0
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1answer
240 views

Is setting CentOS user home-dir as NGINX server block root secure for vsftpd?

This is what I did: CentOS 6.2 server installed nginx installed vsftpd in vsftpd.conf I set chroot_local_user=YES created a new user "bleh" created directory /home/bleh/public_html/ in virtual.conf ...
0
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1answer
31 views

Is it OK to copy /etc/sysconfig/iptables to another machine?

This is my original server with very loose security given that it does not block all ports via iptables. /etc/sysconfig/iptables contents: # Generated by iptables-save v1.4.7 on Mon Jun 16 ...
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3answers
17k views

How do I recover from the Heartbleed bug in OpenSSL?

CVE-2014-0160 a.k.a. Heartbleed is a vulnerability in OpenSSL. It looks scary. How do I determine whether I am affected? If I'm affected, what do I need to do? Apparently upgrading isn't enough.
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1answer
40 views

How can I tell why I have permissions to read a file? [closed]

Here's what I just noticed on my CentOS SSH account: stat output $ stat /dev/kvm File: `/dev/kvm' Size: 0 Blocks: 0 IO Block: 4096 character special file Device: ...
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0answers
17 views

Running unsigned javaws code

For a KVM remote console I need to be able to run a jnlp file. When I run it I get: net.sourceforge.jnlp.LaunchException: Fatal: Initialization Error: Could not initialize application. at ...
2
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1answer
23 views

setup sudoers to mount network shares and loop devices and misc

I would like to setup sudoers to grant users to mount all kind of network shares and loop devices to their home directory. Here is a try that I found and changed a bit on one old post in ...
3
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2answers
121 views

How to implement logwatch functionality on top of systemd journal?

Logwatch scans logfiles with regular intervals, collects errors and stuff, then mails it to the admin. This was back in syslog and logfiles days. What's the corresponding solution for systemd's ...
8
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3answers
5k 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 ...
3
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3answers
48 views

Monitor all login attempts

Few weeks ago I thought it would be a good idea to write a script to send me an email whenever some user logs in into my server. So I came with a perfectly working script notifyLogin.sh, then I ...
5
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2answers
638 views

Setting ulimit correctly for PHP on Linux

I have /etc/security/limits.conf set to the following: nobody soft nofile 409600 nobody hard nofile 1024000 phpuser soft nofile 409600 phpuser hard nofile 1024000 httpd soft nofile 409600 httpd hard ...
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2answers
86 views

Shell Script - how to scp into remote server and download files and protect password

I have a remote server that I need to download Apache logs from. I can manually scp into the server and get the files, but I'd like to put this in crontab. The only way to automate it is to include ...
5
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2answers
137 views

Why ssh-agent group ownership is not root

Trying to understand why ssh-agent has sgid bit and found this post ssh-agent has sgid I have another question, why the group ownership of ssh-agent is nobody not root? What is the reason behind it? ...
4
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1answer
94 views

How safe is sudo when running from root to run an application as a less privileged user?

Lets say I am logged in at a root terminal and I run something like the following command: sudo -u '#1000' dbus-launch chromium Are there any potential security issues I should be worried about? ...
3
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1answer
280 views

Is there any DLP solution for linux?

I'm looking for a DLP (Data Leak Prevention) solution for linux environments. I know OpenDLP, but it's only a way to Prevent Clear-text file, and source codes from malicious access. There are lots of ...
1
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1answer
32 views

SSH slow after configuring TCP Wrappers

We have SSH open on one of our production servers leaving it prone to various brute force attacks to break in. I reduced the attempts by changing the default port from 22. I want to further harden ...
2
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1answer
29 views

Why isn't 'nethogs' installed with the setuid bit set?

I've been using nethogs for a while now, having to sudo every time, while ping has the setuid bit set. Today I set it for nethogs and it works: $ ls -l $(which nethogs) $(which ping) -rwxr-xr-x 1 ...
3
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2answers
35 views

chroot jail that can access the filesystem

chroot jails seem to be simply a different world, with no interaction with the actual filesystem. Thus, the entire environment has to be replicated inside the chroot, which would mean making a full ...
4
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1answer
47 views

Why doesn't GCM HTTPS work with nginx?

Since these two are using GCM (Galois/Counter Mode): www.ssllabs.com: ECDHE-RSA-AES256-GCM-SHA384 www.google.com: ECDHE-RSA-AES128-GCM-SHA256 We wanted to make our webserver's HTTPS connection ...
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0answers
62 views

Limit program execution to a list of arguments

I would like that my Unix users can only run a specific command insecurecommand with a controlled list of arguments stored in a file. The only solution I have found at this time is to : Create a ...
3
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1answer
35 views

Securing VPS against access by server company

I have a few linux VPS boxes that contain the private keys to Bitcoin. I've taken a few steps to harden them: Blocked all ports except those needed for my server with uncomplicated firewall Disabled ...
3
votes
3answers
252 views

What are the world writable directories by default?

In a standard Linux filesystem, which of these common directories are world-writable by default? /tmp /etc /var /proc /bin /boot /.... .... Why are they world-writable? Does that pose ...
5
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0answers
49 views

Does Android's implementation of SELinux's M.A.C. inhibit root apps with root privileges from accessing app data?

Starting with Android 4.4 SELinux's MAC is enforced. Does this mean that if an app somehow can get installed and exploit the kernel to get root privileges, that MAC will still prevent that app with ...
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2answers
43 views

Permissions under a 700 (rwx------) directory

If a directory /foo/bar/baz has 700 (rwx------) for its permissions, thereby making it inaccessible to all but its owner (and the superuser), does it matter what the "group" and "other" permissions ...
2
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1answer
20 views

Credential in PPD file: Is there a way to hide it?

We have a copying machine that can be used as a printer. In order to do that, I have to provide a credential in plain in the Xerox.ppd file. Problem: Any user on the system can grep credential ...
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0answers
25 views

apache mod_security and performance

I have a list of bots to block, so I was thinking that fail2ban could be a solution until I realized that mod_security would be more efficient in this kind of tasks. The number of bots is huge, so ...
3
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1answer
54 views

Monitoring filesystem activity

Say, I have a program, and I want to monitor its filesystem activity (what files/directories are created/modified/deleted etc.) This program may be capable of spawning further processes, and thus, I ...
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2answers
76 views

Why are custom programs always installed in /opt, /srv, /usr/local, etc. and not in ~/ (home) folder?

The LTS repo is pretty good, but for some reason I prefer the "build from source" method for some programs. One reason is that I get the preferred version (PHP on LTS is on 5.3, whereas I can compile ...
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1answer
66 views

Heartbleed Bug, which OpenSSL services are vulnerable to the leak?

I'm getting ready to patch my server (Debian Wheezy), and it's going to be a pain because I built a lot of it from source (Apache 2.4, PHP, MySQL). Before I get started patching, I'd like to have a ...
6
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3answers
162 views

Force Firefox to remember passwords on particular sites

Usually, when I log into a website with username and password, Firefox asks whether it should remember the login details. When I click yes, next time I visit the website, the username and password ...