Category: CentOS

Link: How to Create Self-Signed SSL Certificates and Keys for Apache on RHEL/CentOS 7.0

SSL (Secure Sockets Layer) is a cryptographic protocol that allows secure data flow between a server and its clients using symmetric/asymmetric keys by using a digital certificate signed by a Certificate Authority (CA).

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This tutorial provides an approach on how to set up Secure Sockets Layer (SSL) communication cryptographic protocol on Apache Web Server installed in Red Hat Enterprise Linux/CentOS 7.0, and generate self-signed Certificates and Keys with the help of a bash script which greatly simplifies the entire process.

Full article here:
How to Create Self-Signed SSL Certificates and Keys for Apache on RHEL/CentOS 7.0 (Tecmint)

Links: Setup DHCP Server On CentOS 6.5 or Ubuntu 14.04 LTS Server

DHCP Server is used to distribute IP addresses to the clients in your network. DHCP stands for Dynamic Host Configuration Protocol. It reduces the work burden to a system admin if he/she have to assign IP addresses manually to more than 100+ systems.

Full articles here:
Setup DHCP Server On CentOS 6.5 (Unixmen)
Setup DHCP Server On Ubuntu 14.04 LTS Server (Unixmen)

Setup Local Mail Server Using Postfix, Dovecot And Squirrelmail on CentOS 6.5/6.4 or OpenSUSE 13.x

Postfix is a free open source mail transfer agent (MTA). It is easy to administer, fast and as well as the secure MTA. It’s an alternative to Sendmail, which is the default MTA for RHEL.

Well, let us see how to setup a basic local mail server using Postfix, Dovecot and Squirrelmail On CentOS 6.5 [or Opensuse], although it should work on RHEL, Scientific Linux 6.x series [or SLES Servers].

Full articles here, from Unixmen:
Setup Local Mail Server Using Postfix, Dovecot And Squirrelmail On CentOS 6.5/6.4
Setup Local Mail Server Using Postfix, Dovecot And Squirrelmail On OpenSUSE 13.x

Links: The DIY home VPN experiment series

Part One: Introduction

It’s been a while since my last blog entry, and I’ve decided to catch you up on some of the projects that I’ve been working on in my home lab. This next series of posts is going to revolve around the do-it-yourself home VPN.

What is a VPN, or virtual private network?

“A VPN is a communications environment in which access is controlled to permit peer connections only within a defined community of interest, and is constructed though some form of partitioning of a common underlying communications medium, where this underlying communications medium provides services to the network on a nonexclusive basis [1].”

In essence, a VPN is private and controlled network communication over a non-private medium – the Internet.

Full articles here (source: empiric virtualization):
Introduction.
Generating a PKI (Public Key Infrastructure) for my OpenVPN.
My Virtualized OpenVPN Server.
Deploying OpenVPN using CentOS on a Raspberry Pi.

Link: 20 Linux YUM (Yellowdog Updater, Modified) Commands for Package Management

In this article, we will learn how to install, update, remove, find packages, manage packages and repositories on Linux systems using YUM (Yellowdog Updater Modified) tool developed by RedHat. The example commands shown in this article are practically tested on our CentOS 6.3 server, you can use these material for study purpose, certifications or just to explore ways to install new packages and keep your system up-to-date. The basic requirement of this article is, you must have a basic understanding of commands and a working Linux operating system, where you can explore and practice all the commands listed below.

Full article here:
20 Linux YUM (Yellowdog Updater, Modified) Commands for Package Management (Tecmint)

Link: Linux: Keep An Eye On Your System With Glances Monitor

Is there is a tool that can provide me a maximum of information (such as cpu, disk I/O, network, nfsd, memory and more) about my Linux/Unix server in a minimum of space in a terminal?

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Say hello to Glances

From the project home page:

Glances is a free (LGPL) cross-platform curses-based monitoring tool which aims to present a maximum of information in a minimum of space, ideally to fit in a classical 80×24 terminal or higher to have additionnal information. Glances can adapt dynamically the displayed information depending on the terminal size. It can also work in a client/server mode for remote monitoring.

Full article here:
Linux: Keep An Eye On Your System With Glances Monitor (nixCraft)

Note that in addition to the above article, the project page for Glances can be found here.

Link: Do More, Faster In The Linux Terminal With Midnight Commander

This is the program we always install first in any new Linux-based installation, and if for some reason we can’t install it, that system tends to get blown away and replaced by a different version of Linux (or whatever) almost immediately. Not being able to install Midnight Commander is kind of a deal-breaker around here.

File browsing in a Linux terminal is alright, but it could be so much better. Midnight Commander is the program you’re looking for –  it gives you a two-paned file browser that makes working in the terminal so much easier. And the best part? It’s simple to get and use.

Full article here:
Do More, Faster In The Linux Terminal With Midnight Commander (MakeUseOf)

We’ll just add that even some Mac OS X users are apparently lost without Midnight Commander, since an older article on installing it under OS X is still one of the most popular on this site, even though for day-to-day use, we would think that most OS X users would be happier with the more recent versions of XtraFinder, which now includes dual pane functionality (and it’s free!). As for Windows users, there is always the venerable Total Commander.

How to make FreePBX and other Asterisk-based systems send voicemails and notifications to two or more email addresses

FreePBX and Asterisk do not allow you to send voicemails and notifications to multiple email addresses. But, there is a way to do it. Here are the simple steps:

  1. From a Linux command prompt, open the file /etc/aliases in your favorite text editor. Add a line to the end of that file, using a descriptive name that should not duplicate any of the names already in this file, nor the username of any users on the system. The line should look like this (this is just an example, obviously):
    foo: user1@gmail.com,user2@gmail.com
    Where foo can be replaced with any alias name you like that does not duplicate an existing alias or username.  You can add as many email addresses as you need, but they should be separated only by commas, and NO spaces other than the one between the alias name and the first email address.
  2. From the Linux command prompt, run the command newaliases and make sure that no errors are reported (you should not see any output at all).
  3. If you are running raw Asterisk, then wherever you would normally use a single email address, you can now use the alias name @localhost, for example, foo@localhost.
  4. If you are using an old version of FreePBX then it may not allow you to use addresses ending in @localhost. In that case, from the Linux command prompt run the command hostname -f and then use the result of that in place of localhost in step 3.
  5. You can repeat these steps as needed to create additional aliases for different users on your system.  You might want to use meaningful alias names, for example mikevm to send Mike’s voicemails to multiple addresses.
  6. Don’t forget that if you are only sending voicemail notifications, and not the entire voicemail as an attachment, that many wireless companies have SMS gateway addresses that you can send an email to, that will convert the first 140 characters of the email to an SMS text message.  You can find a list of email address formats to use for this purpose in this article:  How To Send Email To Any Cell Phone (for Free)
  7. This technique is not limited to Asterisk and FreePBX; it should provide a solution for any software that can’t seem to deal with more than one email address at a time.

Link: How to clean up disk space on Linux

BleachBit is an open-source disk space cleaner software, available on Linux and Windows platforms. Besides cleaning up disk space, BleachBit can also shred files securely, and wipe out unallocated disk space for your privacy.

In this tutorial, I will describe how to clean up disk space on Linux by using BleachBit.

Full article here:
How to clean up disk space on Linux (Xmodulo)