[OpenStack]: from keystoneclient.shell import main ImportError: No module named shell
During one node installation of OpenStack Kilo, I tried creating a tenant and the keystone service failed with an error...
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How to Fix Package installation error – Unable to correct problems, you have held broken packages
Question: I was installing few OpenStack packages on Ubuntu 14.04.4 LTS and landed up with an error Unable to correct...How to create a Linux bootable USB stick on Windows
I need to install Ubuntu on my rack server which didn’t come with the CD-ROM drive, but had USB ports on...How to Fix the Error – ModSecurity: Access denied with code 44 [Apache]
Question: I was trying to upload a PDF file of size 2MB in MediaWiki and hit with 500 internal server...How to Send Mail via External SMTP server using mailx command in Linux?
By default, the mail command in Linux will make use of the local SMTP server running on port 25 for...[Solved]: Perl Error – Undefined subroutine &Scalar::Util::blessed
I have been using OpenCA for managing a certificate authority and only to be shocked when it broke last night. All of a...What is Docker, Difference between Docker and VM, Installation of Docker and its usage
Previously we have seen the installations of hypervisors like Xen and cloud middleware like openstack. Recently a new technology called...How to use CONNECT Method on a HTTP Proxy using Telnet?
I generally use telnet command to test whether a given port is listening on a remote machine. For e.g., telnet...How to Install Proxychains and Access Internet via Proxy in CentOS?
If your Linux machine is behind a proxy server, then you can install Proxychains package to access internet via the given...How to Install Hping Network Security tool on CentOS7
Hping is a command line TCP/IP packet assembler/analyzer with embedded Tcl scripting functionality. Inspired by the ping command, Hping was...How to Fix DROWN Vulnerability in Apache/NGINX Web server and SMTP?
Here’s a latest vulnerability called DROWN (Decrypting RSA with Obsolete and Weakened eNcryption) that aims to attack servers using weak...How to use libguestfs tools to Edit Virtual machine (VM) Disk Images in CentOS/RHEL/Fedora?
Question: By mistake I had disabled ‘root’ account in a CentOS Virtual machine running in VMWare. Thereafter, I tried all...How to Extract Audio from YouTube Videos and Save it as mp3, wav using youtube-dl command-line tool in Linux?
This tutorial will guide you to install a simple command-line utility called youtube-dl that allows you to extract audio from...How to Fix ‘ERROR: WARNING: unable to obtain file audio codec with ffprobe’? [Solved]
Question: I was using youtube-dl command-line utility on CentOS to extract an audio from YouTube Video. However, the command failed with...How to Compile and Install FFmpeg from source in CentOS/RHEL?
I got an ERROR: ffprobe or avprobe not found while installing youtube-dl command-line utility on CentOS. This tutorial will show you on...How to Install or Update autoconf and automake on RHEL/CentOS?
Question: I was installing ffmpeg with Yasm support, during which I need to use autoconf to generate configuration script on...[Solved]: How to Prevent Virtual Machine’s clock Synchronizing with Host machine and Set Independent clock time?
Question: In my CentOS 5 VM (running on Xen server), the date command displays wrong output (as 16 Jun 2015 07:05:11...How to configure a Linux Bridge to act as a Hub instead of a Switch
A bridge is a device that separates two or more network segments within one logical network. A bridge is one...How to fix Python Installation Error while loading shared libraries: libssl.so.1.0.0? [Solved]
Question: Thanks to the guide on How to compile and install Python with OpenSSL Support. However, the installation failed with an...Python Error – urllib2 URLError: urlopen error unknown url type: https [Solved]
Question: I got this error urllib2.URLError: <urlopen error unknown url type: https> while installing packstack. After checking the program, I understood that...