Automated Root SSH Access Setup via Shell Script on EC2

☁️ Step-by-Step EC2 Instance Setup with Root SSH Access

✅ 1. Launching a New EC2 Instance

• Go to AWS Management Console > EC2 Dashboard

• Click on Launch Instance

• Choose an Amazon Machine Image (AMI) — e.g., Amazon Linux 2

• Select the desired Instance Type (e.g., t2.micro)

Click Next to move to configuration

✍️ 2. Add User Data Script (Root SSH Setup)

• Scroll down to Advanced Details

Paste the following User Data (shell script):

#!/bin/bash

# Set root password
echo "root:Apurv@123" | chpasswd

# Enable root login and password authentication
sed -i 's/^#\?PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config
sed -i 's/^#\?PasswordAuthentication.*/PasswordAuthentication yes/' /etc/ssh/sshd_config

# Restart SSH service
if systemctl list-units --type=service | grep -q sshd.service; then
    systemctl restart sshd
elif systemctl list-units --type=service | grep -q ssh.service; then
    systemctl restart ssh
fi

📌 Note: Change demo@123 to your secure custom password

🔒 3. Configure Security Group

• Add Inbound Rule:

  • Type: SSH

  • Port: 22

  • Source: My IP or Anywhere (for testing only)

4. Generate or Use Existing Key Pair

• Create a new key pair (.pem) or use an existing one.

• Save it securely — required for connecting via SSH.

🚀 5. Launch the Instance

• Click Launch and wait for the instance to start.

• Once running, note the Public IPv4 DNS or Public IP.

6. Connect to EC2 via SSH

• Open terminal or PowerShell

ssh -i "task-3-insatnce-key.pem" ec2-user@ec2-<public ip>.compute-1.amazonaws.com

Once the root login and password authentication were enabled using User Data, here’s how I accessed the instance from a second EC2:

🧩 1. Launch a Second EC2 Instance

• Go to AWS EC2 Dashboard again

• Launch another instance (can be same AMI and type)

• Ensure both instances are in the same VPC or same region (for private IP access)

• Add a Security Group rule to allow SSH from the second EC2

🔗 2. Connect to Second EC2 (the “Client”)

• SSH into the second EC2 from your local machine:

ssh -i "second-ec2-key.pem" ec2-user@<Second-EC2-Public-IP>

🔐 3. SSH into First EC2 from Second (Using Password Login)

• From the second EC2 terminal, run:

ssh <main-server-private>
#enter passwd:-demo@123

✅ Access granted! You’re now logged in as root to the first EC2 from the second.

🛡️ Security Tip

• This method is useful for internal testing, jump server setup, or remote debugging

• Always ensure restricted access via security groups and rotate passwords regularly

• For production, prefer using SSH key pairs and non-root users