Root user password reset in Ubuntu

You can reset your root / user password if not able to login to your Desktop. Follow below steps and you will be able to login easily.

Step 1 : While booting press and hold shift key.  You will get a screen as below.

Step 2: Select Linux recovery mode and hit enter, you will get a screen as below. 

Step 3: Scroll and select root drop to root shell prompt option then you will  see a shell screen in the bottom.

Step 4: You have to mount your drives so now type in the shell as

mount –o rw,remount /

step 5 : Now if you want to know the users in this computer type

ls /home

step 6 : It will show the list of users in computer. now for example if you want to reset the passwd of  susan user, then type as

passwd susan (i.e, passwd username)

step 7 : Now it will ask for a new unix password, enter the required passwd.

Step 8: Again retype the passwd.

Step 9 : Now you have successfully changed your password. So type exit. It will take you to the screen as below.

Step 10 : Select resume so that your computer reboots.

Note: Some computer does not go back to GUI mode, don’t worry just restart your system once. It will be fine.

 PASSWORD RESET DONE!!!

Blocking USB Storage drives in Linux

Blocking USB Storage drives in Linux

Blocking usb stick

STEP 1: Create and edit a file "no-usb" as below.

#vi /etc/modprobe.d/no-usb

STEP 2: Add the following lines to the above created file.

Install usb-storage /bin/true

STEP 3: Save and exit using ESC :wq

STEP 4: Reboot the computer and try inserting USB Mass Storage drive

USB blocked

To unblock.

Remove the added line from the file "no-usb". 

Refresh the system. It should be unblocked.

Operating System - OS

Operating System - OS

Every Machine/Hardware is made user-friendly with the help of Many Codes/Programs. These Programs/Codes are collectively named as a Software. The Operating system is a collection of Software without which Most Hardware/Machine does not operate.

There are so many operating systems people using around the world. It is my perception that whenever there is a Technology Growth/Change, it is because of development of New Code/Program/Software designed. 

So far i have come across a few Operating systems(OS). Many of us would be famous with Windows - The so called Microsoft Windows OS.

Microsoft OS versions.

MS-DOS

Windows 98

Windows XP

Windows Vista

Windows 7

Windows 8

Windows 8.1

Windows 10.

Unix

MAC OS X

HP-linux

IBM - Aix

Oracle - Solaris

Linux

RedHat Enterprise Linux (RHEL)

Centos

Ubuntu/Kubuntu/Lubuntu

Fedora

Suse Enterprise Linux

Linux Mint

and several others

Mobile - OS

Android

IOS

Windows

Operating system may be defined in many other ways. To keep it very simple, we can understand that operating system is a language that helps to interpret Our instructions to Machine understandable code for it to operate effectively/efficiently.

DNS server configuration using BIND

DNS stands for Domains Name System.

Below are the steps to configure a basic dns server


Few records used here are.
Mail Exchange record (MX record) - Used for exchanging mails.
A record - used to translate from a domain name to an IP address.
NS record -  lists which name servers can answer lookups on a DNS zone.
PTR record - Pointer record.

Step 1: Download & Install bind using following command.

# yum install bind bind* caching-nameserver

Step 2: Disable selinux&iptables.
#

Step 3: change your hostname to a fully qualified domain name.

Step 4: edit the hosts file as shown below,

Step 5: change the dns value as your required IP & Reboot the computer once.

Step 6:create a new file named.conf as below

# vi /etc/named.conf

Step 7:Create zones in /var/named as shown below,

# vi /var/named/zimoncloud.com.db

For forward lookup zone,

#vi /var/named/1.168.192.db

For reverse lookup zone

Step 8: Start the named service using following command.

# service named start

Step 9:To check whether dns is configured properly, issue the following command,