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Linux IfConfig Tutorial

The network configuration is one of the first topics a system administrator gets involved with. For Linux, the command to configure this is ifconfig (contraction of interface and configuration), which allows to make almost any configuration in a network, as we will see in this tutorial. Basic knowledge about networking (what IP addresses are, their format, subnetting, etc.) is assumed ...

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Arduino as a wireless HTTP client

There are many aspects one must take into consideration when it comes to picking the right board for their project – from performance, memory, battery life, available slots for SD cards or bee modules all the way to the connectivity, namely network interface. Whether it is wired or wireless network interface, it plays crucial role in the way the board ...

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Systemd and Upstart Services

Most linux servers that I use are either Debian based or RedHat based. A common task is adding daemon services. Suppose that we want to start a tomcat application on startup First we shall install tomcat mkdir /opt/tomcat groupadd tomcat useradd -s /bin/false -g tomcat -d /opt/tomcat tomcat wget http://apache.cc.uoc.gr/tomcat/tomcat-8/v8.0.33/bin/apache-tomcat-8.0.33.tar.gz tar xvf apache-tomcat-8.0.33.tar.gz mv apache-tomcat-8.0.33/* /opt/tomcat rm -r apache-tomcat-8.0.33 apache-tomcat-8.0.33.tar.gz cd ...

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How to use the sudoers file to grant superuser privileges in Linux

In a Linux system there are tasks that need to be performed using administrative privileges (also known as superuser permissions) as they either impact the system as a whole (for example, managing packages or restarting services) or other users (adding or modifying user accounts, changing passwords or other users). Another example of a task requiring superuser privileges consists of changing ...

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Crouching Supervisor, Hidden File Descriptor Setting

Here’s an interesting problem our team faced last month that was extremely infuriating. We were in the process of launching replacement haproxy instances that are used to load balance to nodes in our RabbitMQ cluster. We’ve done this a lot of times before and set all the usual user settings required under limits.d to ensure proper file descriptors are allocated ...

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Top Online SysAdmin Courses to Boost your Career

Do you want to know what is the best investment you can make with your time and money? Knowledge As a software developer you should be constantly acquiring new skills. This is the best way to advance your career and enjoy the rewards (monetary, emotional etc.). Towards that direction you should be reading books, devouring technical articles and staying informed ...

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Salt SSH Installation on Centos 5.5

Salt has the option to manage servers agentlessly. Agentless means that the targets don’t need a agent process. The master orchestrates the target system over SSH. Therefor it exists an own command called salt-shh. The following sections explain how to install Salt SSH on a CentOs 5.5 and how to configure minimally a master and its targets for a test ...

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Mono on Linux and feeling good

If you haven’t heard about Mono on Linux then it is time to fill this gap. Mono is an open source platform that implements CLI specification and enables building and running C# applications on Linux, OS X, Windows which is fun. This is the official description from the site. Mono, the open source development platform based on the .NET framework, allows ...

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Using Squid as an HTTP Proxy via SSH (to fetch remotely from Amazon yum repos)

We’ve been playing around with vagrant for local development.   When combined with Ansible, the pair allows you to recreate complex systems locally with high fidelity to your deployment environment. Through magic voodoo (kudos to @jjpersch and @kmolendyke), we managed to get an Amazon AMI crammed into a virtual box.  Unfortunately, Amazon’s yum repos are only available from the EC2 network. ...

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