Tag Archives: linux

How To Install WordPress in Ubuntu Server 12.04 LTS

Install the LAMP Server (Linux,Apache, Mysql, PHP) with the command below:

sudo apt-get install lamp-server^

It will prompt for mysql server root password, enter the root password:

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Configure the DHCP server dynamically update the DNS records on Ubuntu 12.04LTS

 This tutorial is based on Ubuntu 12.04 LTS, in which I will try to show you that how to configure the DHCP server automatically update the DNS records, when it assigns a new lease to a client on local network. We will use the below network diagram as a base for this tutorial:

Before Starting this tutorial:

Before starting this tutorial, you can check my other tutorials to learn that, how i configure DHCP server and Gateway:

Ubuntu as a firewall/gateway router

How to Install the DHCP Server on Ubuntu 12.04LTS

Network Configuration for the Ubuntu Gateway:

Configure the DNS:

Install the DNS (bind9) using this command:

sudo apt-get install bind9 dnsutils

Also edit the hosts settings so that the server will be able to accepts the DNS requests. Here is an example of my server’s host file:

cat /etc/hosts

Move to the bind directory:

cd /etc/bind/

Next, we need to configure the forwards for bind, I am using Google’s DNS servers as an example:

sudo nano named.conf.options

forwarders {;;

Now we create a secret key that will be shared between the DHCP server and the DNS:

sudo dnssec-keygen -r /dev/urandom -a HMAC-MD5 -b 128 -n USER DHCP_UPDATER

Show the generated key:

sudo cat Kdhcp_updater.*.private|grep Key

Edit the named.conf.local file in /etc/bind/ directory:

sudo nano named.conf.local

Define the locations of the forward and reverse zone files as well as the secret shared key here:

Move to the /var/lib/bind/ directory:

cd /var/lib/bind/

Create the forward zone file for your doamin:

sudo nano tendo.local.db

Replace the tendo.local with your domain name. Here’s an example of my forward zone file:

$TTL 907200 ; 1 week 3 days 12 hours
tendo.local IN SOA dnssrv.tendo.local. arbab.tendo.local. (
                   2012071707 ; serial
                   10800 ; refresh (3 hours)
                   3600 ; retry (1 hour)
                   604800 ; expire (1 week)
                   38400 ; minimum (10 hours 40 minutes)
                   NS dnssrv.tendo.local.
$ORIGIN tendo.local.
dhcpsrv            A
dnssrv             A
gateway            A

Every time you make the changes to the zone file, you need to change the serial before reloading the bind.

Next, create the reverse zone file for your doamin:

sudo nano 10.16.172.rev

Here is my reverse zone file, replace the hosts and domain name with your own that match with the forward zone file just created above:

$TTL 907200 ; 1 week 3 days 12 hours
10.16.172.in-addr.arpa IN SOA dnssrv.tendo.local. arbab.tendo.local. (
                       2012071706 ; serial
                       10800 ; refresh (3 hours)
                       3600 ; retry (1 hour)
                       604800 ; expire (1 week)
                       38400 ; minimum (10 hours 40 minutes)
                       NS dnssrv.tendo.local.
$ORIGIN 10.16.172.in-addr.arpa.
1                      PTR dnssrv.tendo.local.
2                      PTR dhcpsrv.tendo.local.
254                    PTR gateway.tendo.local.

Restart the bind service:

sudo /etc/init.d/bind9 restart

Configure the DHCP server to send updates to the DNS:
sudo nano /etc/dhcp/dhcpd.conf

Add the secret key that we created on our dns server in the dhcpd.conf file and other option, some of the main configurations are mentioned below:

For given subnet, we need to define the zones and within the zones, we need to tell the DHCP server which key to use to update the DNS server:

Here is a DHCP scope that will be used to assign the IP configuration to the clients:

Restart the dhcp service:

sudo /etc/init.d/isc-dhcp-server restart

Once again, restart the bind service on DNS server:

sudo /etc/init.d/bind9 restart

Check the log messages on both dns and dhcp servers:
sudo tail -f /var/log/syslog

DHCP server successfully add the client to the forward and reverse zone.

DNS server accept the secret key and update it’s forward and reverse zone.

Verification on dhcp client:

Enjoy 🙂


I found some really nice troubleshooting steps regarding dhcp and dns server here (Thanks to original author):

  • error: zone [zone-name]/IN: NS ‘[dns-server-hostname]‘ has no address records (A or AAAA)
    You’ll probably encounter this if you forget to provide records for your DNS server in your zone files; e.g. [dns-server-name] IN A [dns-server-ip-address]
  • error: [some-zone-file]: create: permission denied
    Check to make sure that permissions on the given file are correct. Configuration files must be readable by the bind user, and zone/journal files must be writable by the bind user.
  • updating zone ‘[zone-name]/IN’: error: journal open failed: unexpected error
    It is possible that Ubuntu’s AppArmor is getting in the way of the zone updates. Make sure you check /var/log/syslog for related messages. Also check the AppArmor configuration at /etc/apparmor.d/usr.sbin.named.
  • error: zone [zone-name]/IN: [some-hostname]/A: bad owner name (check-names)
    The hostname that a client is requesting is invalid for use in a FQDN. Change the client’s hostname.
  • error: zone [zone-name]/IN: journal rollforward failed: journal out of sync with zone
    The zone journal file has gotten out of sync with the zone file (usually occurs with forced restarts, or modifying the zone file while BIND9 is running). Delete the .jnl file (in/var/lib/bind), and restart BIND9.

Hope this will help you!

Please Remember me in your prayers!

How to find the Linux Distribution Name and Version

In this post, I will try to show you that how we can check the version of Linux (Debian, Fedora, Ubuntu, CentOS), a particular system is running. Sometime we login to the system but we don’t know that which Linux distribution is running on it, So in this post, we will try to find it by using the lsb_release command that displays certain Linux Standard Base(LSB) and distribution-specific information.

To show the release number of installed distribution:
lsb_release -r

To show the distributor ID:
lsb_release -i

 To show all of the above information:
lsb_release -a

To find Out the Kernel Version by using this command:
uname -mrs


Linux – Kernel name
3.2.0-24-generic – Kernel version
x86_64 – Kernel is 64-bit

Hope this will help you!

Please Remember me in your prayers!

OSPF routing between Cisco,Ubuntu,CentOS and Mikrotik Router!


  • Routers: 1 Ubuntu Linux with 3 nics, 1 Centos Linux with 3 nics, 1 Cisco 3640 Router with 3 FastEthernet interfaces and 1 Mikrotik Router with 2 interfaces.
  • Clients: 3 Windows Xp with 1 nic.
IP Details

All the Routers in this scenario have a default password of “zebra“.

Cisco Router:

  • fe0/0:
  • fe1/0: /24
  • fe2/0: Getting through DHCP


  • eth0:
  • eth1:
  • eth2:


  • eth0:
  • eth1:
  • eth2:

Mikrotik Router:

  • ether1:
  • ether2:


  • Ubuntu-Desktop:
  • WinXP-1:
  • WinXP-2:
  • WinXP-3:

Cisco Router Configuration:

UbuntuRouter Configuration:

Restart the Router!!!

CentOSRouter Configuration:

Restart the Router!!!

Mikrotik Router Configuration:

Neighbor verification from Routers:

Route verification from Routers:

Test from Clients:

Make a simple test from Ubuntu-Desktop.

Make a simple test from WinXP-1.

Make a simple test from WinXP-2.

Make a simple test from WinXP-3.

Configure NAT on Cisco Router:

This is just a bonus section, in which we will configure the NAT on Cisco router and also propagate the default route in OSPF. I connect my Cisco Router to DSL Modem and configure it so that it will take IP address through DHCP, as well as configure the inside and outside interface for NAT.

Lazy man access -list for NAT (This is not the perfect access list):

NAT Overload:

Originate the default route in OSPF:

Verify the last resort information on Cisco Router:

Check default route information on all routers 🙂

Hope this will help you!

Please Remember me in your prayers!

Enjoy 🙂

OSPF routing between Ubuntu and CentOS using Quagga



  • Routers: 1 Ubuntu Linux with 2 nics, 1 Centos Linux with 2 nics.
  • Clients: 2 Windows 7 with 1 nic.

IP Details:

All the Routers in this scenario have a default password of “zebra“.


  • eth0:
  • eth1:


  • eth0:
  • eth1:


  • Dektop:
  • Laptop:

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How to install Webmin on Ubuntu 12.04

Webmin is a web-based interface for system administration for Linux/Unix. You can setup user accounts, Apache, DNS,DHCP, file sharing and much more by using any modern web browser.

First, we need to install the dependencies with the command:

sudo apt-get install perl libnet-ssleay-perl libauthen-pam-perl libpam-runtime 

openssllibio-pty-perl apt-show-versions python

Now, we need to download the Webmin deb package from Sourceforge (I download it  in /tmp directory):

wget http://prdownloads.sourceforge.net/webadmin/webmin_1.580_all.deb

Then just run the command :

sudo dpkg --install webmin_1.580_all.deb

Webmin is installed now and you will be able to access it via a browser using, https://server-ip:10000. In my case it is,https://tendo:10000.

(It will show you the security warning, just accept it)

Enter your Username and Password that you use for login on to your server.

After login, Webmin main page will show you the summary of your server:

Hope this will help you!

Please Remember me in your prayers!

SSH on Ubuntu Server

SSH server on Ubuntu server is really easy and straight forward. Here are a few simple steps that, we will use to install the OpenSSH on Ubuntu server!

Find the ip address of server, so that we can use it to connect remotely:

Now, we will go to remote Windows machine and try to connect to the server:

We are on the same subnet 🙂

We will log in to a remote system (Ubuntu) with SSH using PuTTY:


Hope this will help you!

Please Remember me in your prayers!

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