How to find dormant users on your Linux Box?

Want to know the inactive users on your Linux machine who have not been using the machine since long time? The following simple shell script, called not-this-month, uses the last command to produce a list of the users who haven’t logged in during the current month. Run it the last day of the month to produce a list of accounts that you may wish to disable. #!/bin/sh # # not-this-month: # Gives a list of users who have not logged in this month # PATH=/bin:/usr/bin;export PATH umask 077 mkdir /tmp/NTM || exit 1 chmod 700 /tmp/NTM THIS_MONTH=´date | awk ‘{print...

How to enable Docker behind the firewall?

Are you working in restricted corporate environment? Are you looking for how to run Docker behind the firewall.You can always specify an HTTP proxy for docker to use via an environment variable. First, create a directory for drop-in configuration for docker: #mkdir /etc/systemd/system/docker.service.d Now, create a file called /etc/systemd/system/docker.service.d/http-proxy.conf that adds the environment variable: [Service] Environment=”HTTP_PROXY=http://proxy.example.com:8080″ To apply the change, reload the unit and restart docker: systemctl daemon-reload systemctl restart docker

Restrict maximum simultaneous logins on Linux

Want to restrict simultaneous number of logins attempt on Linux machine? Here is the quick way of doing it. 1. Edit the file /etc/security/limits.conf to make the below changes: #cat /etc/security/limits.conf # /etc/security/limits.conf # #Each line describes a limit for a user in the form: # # # #Where: # can be: # – an user name # – a group name, with @group syntax # – the wildcard *, for default entry # – the wildcard %, can be also used with %group syntax, # for maxlogin limit # – NOTE: group and wildcard limits are not applied to...

PowerCLI Cookbook Published !!

I am very thrilled and excited about Packtpub publisher’s recently published “PowerCLI Cookbook”. I have been part of a reveiwer team and spent couple of months for its accuracy. You can purchase this book at https://www.packtpub.com/virtualization-and-cloud/powercli-cookbook You can check the free chapter at the above link. I am sure you will like the book as lots of effort has gone preparing recipes. Due to the timing for the release of vSphere 6, the publish was delayed but finally it got published. Do provide feedback after reading the book.

VMware vSphere Internals Q/A

Welcome Readers !! This is a second series of VMware vSphere Q/A which is emphasized on ESXi internals and related feature Q/A. I hope it will help you with interview preparation: Que:1>. What is hyperthreading in terms of VMware terminology? Ans: Hyperthreading technology allows a single physical processor core to behave like two logical processors. The processor can run two independent applications at the same time. To avoid confusion between logical and physical processors, Intel refers to a physical processor as a socket, and the discussion in this chapter uses that terminology as well. On processors with Intel Hyper-Threading technology,...

Understanding Docker Container Architecture

What is Docker? Docker is a lightweight containerization technology that has gained widespread popularity in recent years. What does Docker uses? It uses a host of the Linux kernel’s features such as namespaces, cgroups, AppArmor profiles, and so on, to sandbox processes into configurable virtual environments. What does Docker container look like? A Docker container can be correlated to an instance of a VM. It runs sandboxed processes that share the same kernel as the host. The term container comes from the concept of shipping containers. The idea is that you can ship containers from your development environment to the...

Introduction to Docker Containers

What is Docker? Docker is a new open source tool based on Linux container technology (LXC).LXC is an OS level virtualization method for running multiple isolated Linux operating systems or containers on single host. LXC does this by using kernel level name space, which helps to isolate containers from the host. Docker is designed to change how you think about workload/application deployments. It helps you to easily create light-weight, self-sufficient, portable application containers that can be shared, modified and easily deployed to different infrastructures such as cloud/compute servers or bare metal servers. Docker mainly provide a comprehensive abstraction layer that...

VMware vSphere High Availability Q/A

Looking for VMware vSphere High Availability based Interview questions? I have attempted to gather important interview questions which you might find useful for your preparation Here we go – 1.  How will you define VMware HA? As per VMware Definition,VMware® High Availability (HA) provides easy to use, cost effective high availability for applications running in virtual machines. In the event of server failure, affected virtual machines are automatically restarted on other production servers with spare capacity. The High Availability (HA) feature in vSphere 4.1 allows a group of ESX/ESXi hosts in a cluster to identify individual host failures and thereby provide...

How to setup Salt Halite on CentOS 6.5

Setting up Salt Halite is not straightforward process. Its a WebUI for Salt master where you can easily run commands and manage minions. I assume that you have  a master node setup with couple of minion(atleast one). Let’s start with the steps to accomplish it: Starting with Build Process – cd /var/www git clone https://github.com/saltstack/halite cd halite/halite ./genindex.py -C Installation salt-api:      5. yum install salt-api In the end add the master configuration file Add the following content at the end of the file /etc/salt/master as shown: rest_cherrypy: host: 0.0.0.0 port: 8080 debug: true disable_ssl: True static: /var/www/halite/halite app: /var/www/halite/halite/index.htmlexternal_auth:...

SaltStack on CentOS 6.5

SaltStack is an extremely fast and scalable systems and configuration management software for predictive orchestration, cloud and data center automation, server provisioning, application deployment and much more. Today we are going to quickstart with SaltStack to see how effective it is. Let’s deep dive quick into SalStack environmental setup: Machine Details: Machine IP Address Hostname Salt Master 208.64.250.8 208.64.250.8.uscolo.com Salt Minion 1 208.64.250.6 SVM61 Salt Minion 2 208.64.250.7 SVM71 Setting up Salt Master: Let’s see what OS is running on the system #cat /etc/issueCentOS release 6.5 (Final) Kernel \r on an \m Download EPEL repo as the pre-requisite: #wget http://ftp.riken.jp/Linux/fedora/epel/6/i386/epel-release-6-8.noarch.rpm–2015-01-31...