Bash Project

backup_restore_bash_scripts

goal

The goal of These scripts that perform secure encrypted backup and restore functionality,that backup the content of a specific directory, towards a remote server AWS EC2, this script only copies new files and files that were modified for number of days,able to schedule running the backup script on predefined times

Main features

• Backup modified directories
• Upload to EC2 server
• Encrypts backup file using GPG

Requirements

• gnupg tool

  • GPG can be found in most distribution’s repositories out of the box.
    • On Debian and Ubuntu-based systems, install the gpg package:

      sudo apt install gpg

    • If you use Arch based distributions, install the gnupg package with the pacman command:

      sudo pacman -S gnupg            

• SCP Command

  • CentOS 7/RHEL 7:

   sudo yum install -y openssh-clients openssh

  • Ubuntu/Debian:

  sudo apt install -y openssh-client openssh-server

  • Arch Linux:

  sudo pacman -Sy

  sudo pacman -S openssh

• tar

• gzip

scripts

The two scripts backup.sh and restore.sh source backup_restore_lib.sh and invoke the corresponding functions.

1. backup.sh
   • functions
     • validate_backup_params
     • backup
2. restore.sh
   • function
     • validate_restore_params
     • restore

remote server

If you want to use the backup script to upload the backup to a remote server, you must first prepare the AWS EC2 server. You can do this by following the instructions in the AWS documentation.

Automate Backup

It is advisable to create a cron job to run the script regularly in an automatic manner. To do this, open crontab with the following command:

sudo crontab -e

It may prompt you to choose an editor, I generally prefer nano. You can then add a line to the bottom of this file in the following format minute hour day-of-month month day-of-week /path/to/shell/script Eg. 0 5 * * 6 $HOME/backup.sh >/dev/null 2>&1 Save & close the file. This will execute the script at 05:05 every Saturday Also, we mute the execution result by sending the output to /dev/null.

encryption using GPG

How does GPG work for encryption?

GPG keys work by using two files, a private key and a public key. These two keys are tied to each other, and are both needed to use all of GPG’s functionality, notably encrypting and decrypting files. When you encrypt a file with GPG, it uses the private key. The new, encrypted file can then only be decrypted with the paired public key. The private key is meant to be stored in a fashion stated directly in its name – privately, and not given out to anyone. The public key on the other hand is meant to be given to others, or anyone you want to be able to decrypt your files. This is where GPG’s main approach for encryption comes into play. It allows you to encrypt files locally and then allow others to be ensured that the files they received were actually sent from you. As the only way they’ll be able to decrypt the file is with your public key, which would only work if the file was encrypted using your private key in the first place. This also works in the opposite direction! Other people can encrypt files using your public key, and the only way it’ll be able to be decrypted is with your private key. Thus allowing others to publicly post files without worry of people besides you being able to read them.

In other words, if a file was encrypted with a private key, it can only be decrypted with the corresponding public key. And if a file was encrypted with a public key, it can only be decrypted with the corresponding private key.

Encrypting and decrypting files with GPG

This is a very simplistic scenario. I presume that you have just one system and you want to see how GPG works. You are not sending the files to other system. You encrypt the file and then decrypt it on the same system. Of course, this is not a practical use case but that’s also not the purpose of this tutorial. My aim is to get you acquainted with GPG commands and functioning. After that, you can use this knowledge in a real-world situation (if need be). And for that, I’ll show you how you can share your public key with others.

Step 1: Installing GPG

Step 2: Generating a GPG key

Generating a GPG key on your system is a simple one-command procedure. Just run the following command, and your key will be generated (you can use the defaults for most questions as shown in the underlined sections below)

gpg --full-generate-key

Checking the GPG Key

You can then see that the private key and public key are both tied to each other by that ID shown under pub by using the –list-secret-keys and –list-public-keys commands respectively:

Sending and receiving GPG Keys

To send someone a GPG key, you’ll first need to export it from your keychain, which is what contains all of your public and private keys.

To export a key, simply find the key ID in your keychain, and then run the following command, replacing id with the key’s ID and key.gpg with the name of the file you want to save to:

gpg --output key.gpg --export id

To import a key, simply give the output file (from the previous command) to the other user and then have them run the following command:

gpg --import key.gpg

To use the key normally though, you’ll need to verify the key so GPG properly trusts it.

This can be done by running the –edit-key command on the other user’s system, following by signing the key:

gpg --edit-key id

Next, run the fpr command, which will show the fingerprint for the key. The output of this command should be validated against the output on your own machine, which can be found by running the same –edit-key command on your system:

If everything matches up, just run the sign command and everything will be ready to go:

The other user can now start encrypting files with your public key just as you did earlier, ensuring they’ll only be readable by you when you decrypt them with your private key.

working with the script

to use These scripts You must ensure that the scripts executable script Make the script executable with command chmod +x .

1) backup

sudo chmod +x backup.sh

now Run the script

./backup.sh

enter the directory you want to back up i choose ITI for example

if found it ,this message will appear ,enter y if you want to create the key ,n if you have one,then enter number of day enter **user id ** of the key encryption done for subdirectories, enter user id again to encrypt main directory encryption done for the directory now let us upload the file to ec2 server enter the path of private key and dns of ec2

done the file uploaded to ec2 server

2)restore

enter name for temp directory

now enter the encrypted file ,then enter y if you have the encryption key you must have encryption key of the file.

enter the passphrase to decrypt the file

our directory is ready