SSH Connection Basics for Beginners

Securely Connecting with SSH: A Beginner's Guide

SSH (Secure Shell) is a tool that allows you to securely access and control another computer or server 🌐. It’s like a remote control for computers, making it possible to manage files, run programs, and make changes from anywhere as if you were physically present.

What is SSH and How Does It Work?

SSH uses encryption to establish a secure connection between two systems. Here’s how it works:

Keys for Security:

.🔐 Private Key: Your unique key that you keep secret. Think of it as your digital fingerprint.

.🔒 Public Key: The server’s lock that matches your key. It ensures only you can access it.

When you use SSH, your private key verifies your identity, and the server’s public key confirms its authenticity.

Generating Keys with ssh-keygen

ssh-keygen is a command-line tool to create and manage SSH keys.

Key Concepts:

Public Key: Shared to encrypt data.
Private Key: Kept secret to decrypt data.

ssh-keygen :

Follow the prompts to generate a new key pair. The keys are stored in the .ssh directory on your system.

Private key - id_ed25519

Public key - id_ed25519.pub

Connecting Your Local System to an AWS Server

To connect to an AWS server securely, follow these steps:

Locate Your Key File:
- Ensure your downloaded key file (linux.pem) is in your directory.
- Check permissions using:
  
  ls -l linux.pem
Set Correct Permissions:
- Modify the key file to be read-only:
  
  chmod 400 linux.pem
Establish the SSH Connection:
- Use the following command:
  
  ssh -i "linux.pem" ubuntu@<your-aws-public-ip>.compute.amazonaws.com
- Type yes to accept the connection.
  
  you can connect successfully…..

Server-to-Server SSH Connection

If you need to connect one server to another:

Download Key File from AWS:
- Use EC2 Instance Connect to access the server.
- Copy the private key using:
  
  cat linux.pem
Create Key File on the Target Server:
- Create a new key file and paste the copied content:
  
  vim linux.pem
- Save and set permissions:
  
  chmod 400 linux.pem
Connect to the Other Server:

ssh -i "linux.pem" ubuntu@<other-server-public-ip>.compute.amazonaws.com

Downloading Files from a Server to Your Local System

To transfer files securely:

Prepare the Server:
- Create a test file on the server:
  
  mkdir test echo "Hello, World!" > test/hello.txt
- then go to
  
  cd .ssh ( this is directory manage ssh key”s )
  
  vim id_ed25519.pub or cat id_ed25519.pub
  
  copy data
  
  then type vim authorized_keys
  
  paste public key data and save exit
Download File Locally:
- Use the scp command:
  
  scp -i "linux.pem" ubuntu@<server-ip>:/home/ubuntu/test/hello.txt ./ or sudo scp -i "linux.pem" ubuntu@<server-ip>:/home/ubuntu/test/hello.txt ./
  
  The file will now be on your local system.

Why is SSH Important?

SSH provides:

✅ Security: Keeps your data safe from interception.
🌐 Convenience: Manage remote systems from anywhere.
💡 Versatility: Transfer files, execute commands, and debug.

Installing Nginx Using SSH (Example)

Here’s how to install Nginx on a remote server:

Connect to the Server:
Install Nginx:

sudo apt update

sudo apt install nginx -y

sudo systemctl start nginx

sudo systemctl enable nginx

Then go to Dashboard - select ip-id

Then go to public id

Access Nginx:

Open your browser and navigate to http://<your-public-ip>.

for example http://52.**.**.*/ ( your public ip address)

Uninstall Nginx

Using systemctl:

sudo systemctl stop nginx

sudo apt purge nginx

Verify Installation:

apt list --installed | grep ngnix

Note : you can install any type of package

like Docker, Zip, Jenkins, Ansible

Conclusion :

SSH simplifies secure remote management of systems. With its robust encryption and flexibility, it’s a vital tool for administrators, developers, and tech enthusiasts. Start using SSH to manage your systems with ease! 🚀