Archives for Tutorials category

Want to deploy Openstack and experience your own cloud platform the easier way? One way is to install Openstack via RDO Packstack*.
*Packstack is a utility that uses Puppet modules to deploy various parts of OpenStack . It is suitable for deploying both single node proof of concept  or more complex multi node installations.

Components used and tested in:
CentOS 7 Linux 3.10.0-693.el7.x86_64
Openstack Packstack (latest stable release, Pike)

Advisable to stop firewalld, NetworkManager and enable network

#service firewalld stop
#chkconfig firewalld off
#service NetworkManager stop
#chkconfig NetworkManager off
#service network start
#chkconfig network on

Sample Output:


It is meant to function as a staging or testing server where you can  do compatibility test  latest wordpress version on your existing sites, or try themes, plugins,widgets or practice your coding skills in css & php before deploying into your production, then using rpi is a good option.

Components used and tested working:

Raspberry Pi Model B , installed with Raspbian GNU/Linux 8 Jessie (Kernel armv6l Linux 4.9.35+)
nginx(1.6.2-5+deb8u5) (Web Server)
php5 (php5 5.6.33)
mysql 5.5 (ver.5.5.59-0+deb8u1) (Database Server)

Before start the actual installation, update rpi packages

pi@raspberrypi:~ $ sudo apt-get update; sudo apt-get upgrade


Scenario: Multiple network interfaces in your server and each connected to different network and getting the IP via DHCP
Objective: Make all IP pingable and accessible remotely e.g. SSH
Solution: Configure Gateway Routing or setting up multiple default routes for each interfaces

Initially when you connect different links/network (regardless it’s in the same subnet or not) for each of the interfaces, it will end up only one interface is reachable. Why? Because by default, it can only have one default route or gateway on a system.

Example: 5 NIC in 1 Linux Server
Noted: Tested in Redhat based Linux (CentOS,Fedora). Assuming the IP dynamically assigned by the DHCP server:


Objective: to copy/send or tee packets coming from enp3s4f1 and send to a destination IP via the enp3s4f0 management/data port
ServerA = enp3s4f1 (connected to a switch1 span port) (no IP address)
enp3s4f0  (connected to switch2 as management/data port)
(IP is
ServerB destination IP =  (same IP range)

This is based on commer’s post in LQ below:


  1. Configure  the bridge interface and bind enp3s4f1  into it. Disable Spanning Tree Protocol (STP) if necessary. Bring up the bridge interface

#brctl addbr br0
#brctl stp br0 off
# brctl addif br0 enp3s4f1
#ifconfig br0 up


My friend had this Raspberry Pi B+ and wants to use it as a media centre to play his video collection from his NAS storage.  I gave him an option to install Raspbian then install on top those open source media player application. Ended up he wanted the easier way so recommended the OpenELEC. But there’s another thing, he only have Macbook Pro as a laptop.

OpenELEC or short for Open Embedded Linux Entertainment Center, is a free and open source operating system that provides functionality as a complete media center as it is built around Kodi(previously XBMC).

Installation procedure:


Installation & Setup of Free Tacacs+ server in Linux
(Tested via GNS3 & VirtualBox)

Software Used:

-use 3700 IOS as Router & DHCP
-use Ethernet switch to connect hosts
-use VirtualBox guest running on Ubuntu Linux server 12.04.2 LTS



1.Login as root and install dependencies such as tcp wrappers and compilation tools e.g. gcc, bison, flex, make

If you’re not sure if these packages are installed, you can use the command:

dpkg -s [packagename]


root@freelinux:~# dpkg -s gcc bison flex

Package `gcc’ is not installed and no info is available.


For the tutorial “Securing your OpenSSH server in Linux” , key-based authentication is one way to secure your SSH server. Below are the details how it’s done:

Users can login remotely to Secure Shell(SSH) server using public/private key without typing the password. This can put added security on your boxes as it reduces password cracking attempts. Aside from that, it will give convenience to users especially if running scripts that require SCP or SFTP transfers.

These are the steps on doing this:

1. Generate a public/private key pair on the client to identify on the servers. It can be protected with password/passphrase or choose not to have


Securing your OpenSSH server in Linux

Secure Shell (SSH) is a program used to secure communication between two entities, often used as a replacement for Telnet and the Berkeley protocols such as remote shell (RSH) and remote login (Rlogin). SSH is also used as a secure remote copy utility, replacing traditional protocols such as the File Transfer Protocol (FTP) and Remote Copy Protocol (RCP).

For this tutorial, we are going to demonstrate steps on securing your OpenSSH which is a free version of the SSH protocol suite.

Note: Steps 1-9 can be done by  tweaking your sshd_config and do ssh service restart after changes to take effect.


Linux comes with a built-in syslog package that you can use as a centralized syslog server. Basically, it can be used to send all log files from your network devices or appliances in a remote and centralized location. There are also some popular syslog packages for Linux that you can use  such as syslog-ng,rsyslog & splunk syslog server which all offers more features and flexibility.

On this tutorial, we are going to use the syslogd/sysklogd server which is a multi-platform and proven stable software.

[Syslog Server]

1.verify if the sysklogd package is installed.


Install and Configure SNMP client on Linux

The following procedure will install and configure snmp daemon on your Redhat-based distribution such as CentOS & Fedora. Here are the steps:

1. Verify if snmp package is installed, there are few ways

[root@localhost ~]# rpm -qa | grep snmp

[root@localhost ~]# snmpwalk
-bash: snmpwalk: command not found

[root@localhost ~]# ls /etc/snmp*
ls: /etc/snmp*: No such file or directory

This mean net-snmp package is not installed yet

2. Install net-snmp & net-snmp-utils package via yum or up2date


About FLT

This site is dedicated to everyone who likes to learn and explore the beautiful world of Linux. If you have comments and suggestions, please feel free to email at freelinuxtutorials@gmail.com. I am happy to serve and share things esp. that is free and enjoyable as Linux.