Key pairs for SSH access in AWS - Mini Project: Build & Apply

Key pairs for SSH access

📖 Scenario: You are setting up a secure connection to a cloud server. To do this, you need to create a key pair that will allow you to log in safely using SSH without a password.

🎯 Goal: Create an AWS EC2 key pair resource using Infrastructure as Code. This key pair will be used to securely access your cloud server.

📋 What You'll Learn

Create a key pair resource with a specific name

Add a public key material to the key pair

Output the key pair name as a reference

Use valid AWS resource configuration syntax

💡 Why This Matters

🌍 Real World

Key pairs are essential for securely accessing cloud servers without passwords. This project shows how to automate key pair creation for safe SSH access.

💼 Career

Cloud engineers and DevOps professionals often create and manage key pairs to secure server access in AWS environments.

1

Create the key pair resource

Create an AWS EC2 key pair resource named my_key_pair with the key pair name set to my-ssh-key.

AWS

# Your code here to create the key pair resource

Hint

Use the aws_key_pair resource with the name my_key_pair. Set key_name to my-ssh-key and provide a public key string for public_key.

2

Add a variable for the public key

Create a variable named public_key_value to hold the public SSH key string. Assign it the value ssh-rsa [e-mail].

AWS

resource "aws_key_pair" "my_key_pair" {
  key_name   = "my-ssh-key"
  public_key = public_key_value
}

# Your code here to create the variable public_key_value

Hint

Define a variable block named public_key_value with the public key string as its default value. Reference it in the public_key attribute of the key pair resource.

3

Output the key pair name

Create an output named key_pair_name that outputs the key_name attribute of the aws_key_pair.my_key_pair resource.

AWS

variable "public_key_value" {
  type    = string
  default = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7... [e-mail]"
}

resource "aws_key_pair" "my_key_pair" {
  key_name   = "my-ssh-key"
  public_key = var.public_key_value
}

# Your code here to create the output key_pair_name

Hint

Use an output block named key_pair_name to expose the key_name from the key pair resource.

4

Add a tag to the key pair resource

Add a tags block to the aws_key_pair.my_key_pair resource with a tag Environment set to Development.

AWS

variable "public_key_value" {
  type    = string
  default = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7... [e-mail]"
}

resource "aws_key_pair" "my_key_pair" {
  key_name   = "my-ssh-key"
  public_key = var.public_key_value
  # Add tags block here
}

output "key_pair_name" {
  value = aws_key_pair.my_key_pair.key_name
}

Hint

Add a tags map inside the key pair resource with the key Environment and value Development.

Practice

1. What is the main purpose of a key pair in AWS for SSH access?

easy

A. To store server data securely

B. To securely connect to a server without using a password

C. To create a backup of the server

D. To monitor server performance

Solution

1. Step 1: Understand SSH access

   SSH uses keys to allow secure login without passwords.

2. Step 2: Role of key pairs in AWS

   A key pair provides a private key for the user and a public key for the server to verify identity.

3. Final Answer:

   To securely connect to a server without using a password -> Option B

4. Quick Check:

   Key pairs enable passwordless secure login [OK]

Hint: Key pairs replace passwords for secure server login [OK]

Common Mistakes:

• Thinking key pairs store server data
• Confusing key pairs with backups
• Assuming key pairs monitor performance

2. Which AWS CLI command correctly creates a new key pair named MyKey and saves the private key to a file?

easy

A. aws ec2 create-key-pair --key-name MyKey --query 'KeyMaterial' --output text > MyKey.pem

B. aws ec2 create-key-pair MyKey > MyKey.pem

C. aws ec2 generate-key-pair --name MyKey > MyKey.pem

D. aws ec2 new-key --key-name MyKey > MyKey.pem

Solution

1. Step 1: Identify correct AWS CLI syntax

   The correct command uses create-key-pair with --key-name and outputs the private key material.

2. Step 2: Confirm output redirection

   The private key is saved by redirecting the output to a file with > MyKey.pem.

3. Final Answer:

   aws ec2 create-key-pair --key-name MyKey --query 'KeyMaterial' --output text > MyKey.pem -> Option A

4. Quick Check:

   Correct AWS CLI syntax for key pair creation [OK]

Hint: Use create-key-pair with --query 'KeyMaterial' to save private key [OK]

Common Mistakes:

• Using wrong command like generate-key-pair
• Omitting --query to extract key material
• Not redirecting output to save private key

3. You launched an EC2 instance with key pair MyKey. Which command will you use to connect to it if the instance's public IP is 54.12.34.56 and your private key file is MyKey.pem?

medium

A. ssh ec2-user@54.12.34.56 -i MyKey.pem

B. ssh -key MyKey.pem ec2-user@54.12.34.56

C. ssh -p MyKey.pem ec2-user@54.12.34.56

D. ssh -i MyKey.pem ec2-user@54.12.34.56

Solution

1. Step 1: Understand SSH command syntax for key usage

   The -i option specifies the private key file for authentication.

2. Step 2: Confirm correct order of arguments

   The correct syntax is ssh -i private_key user@host. ssh -i MyKey.pem ec2-user@54.12.34.56 matches this exactly.

3. Final Answer:

   ssh -i MyKey.pem ec2-user@54.12.34.56 -> Option D

4. Quick Check:

   SSH uses -i to specify private key file [OK]

Hint: Use ssh -i private_key user@ip to connect [OK]

Common Mistakes:

• Using -key or -p instead of -i
• Placing -i after user@host
• Omitting the private key option

4. You tried to connect to your EC2 instance using SSH but got a permission denied error. Which of these is the most likely cause?

medium

A. The private key file has incorrect permissions (too open)

B. The instance is stopped

C. The key pair was deleted from AWS

D. The instance has no public IP

Solution

1. Step 1: Check SSH private key file permissions

   SSH requires private key files to have strict permissions (e.g., 400). Too open permissions cause denial.

2. Step 2: Understand other options

   While stopped instances or no public IP prevent connection, the error message differs. Deleted key pairs do not affect existing instances.

3. Final Answer:

   The private key file has incorrect permissions (too open) -> Option A

4. Quick Check:

   Private key file permissions cause SSH denial [OK]

Hint: Set private key file permission to 400 or stricter [OK]

Common Mistakes:

• Ignoring file permission errors
• Assuming instance state causes permission denied
• Confusing deleted key pairs with connection errors

5. You lost your private key file for an EC2 instance launched with key pair OldKey. What is the best way to regain SSH access without stopping the instance?

hard

A. Use the AWS console to download the lost private key again

B. Delete the instance and launch a new one with a new key pair

C. Create a new key pair, then update the instance's authorized keys by connecting through Systems Manager or another user

D. Generate a new private key file with the same key name in AWS

Solution

1. Step 1: Understand private key loss impact

   Private keys cannot be recovered or downloaded again from AWS once lost.

2. Step 2: Regain access without stopping instance

   Use AWS Systems Manager or another user with access to add a new public key from a new key pair to the instance's authorized keys.

3. Final Answer:

   Create a new key pair, then update the instance's authorized keys by connecting through Systems Manager or another user -> Option C

4. Quick Check:

   Lost private key requires new key and authorized keys update [OK]

Hint: Use Systems Manager to add new key without stopping instance [OK]

Common Mistakes:

• Trying to download lost private key again
• Assuming new key pair with same name works
• Deleting instance unnecessarily