How to SSH into EC2 Instance: Simple Steps for AWS Access

To SSH into an EC2 instance, use the ssh command with your private key file and the instance's public DNS or IP address like this: ssh -i /path/to/key.pem ec2-user@ec2-instance-address. Make sure your key file has the right permissions and your instance's security group allows SSH (port 22).

Syntax

The basic SSH command to connect to an EC2 instance is:

• ssh: The command to start a secure shell session.
• -i /path/to/key.pem: Specifies the private key file for authentication.
• ec2-user@ec2-instance-address: The username and public DNS or IP of the EC2 instance.

The username depends on the instance OS: ec2-user for Amazon Linux, ubuntu for Ubuntu, etc.

bash

ssh -i /path/to/key.pem ec2-user@ec2-instance-address

Example

This example shows how to SSH into an Amazon Linux EC2 instance using a private key file named mykey.pem and the instance's public DNS ec2-203-0-113-25.compute-1.amazonaws.com.

bash

ssh -i mykey.pem [e-mail]

Output

Warning: Permanently added 'ec2-203-0-113-25.compute-1.amazonaws.com' (ECDSA) to the list of known hosts.
[ec2-user@ip-172-31-16-139 ~]$

Common Pitfalls

• Incorrect key permissions: The private key file must have permissions set to chmod 400 to be secure.
• Wrong username: Using the wrong username (like root) will cause connection failure.
• Security group blocking port 22: Ensure the EC2 instance's security group allows inbound SSH traffic on port 22.
• Using the wrong IP or DNS: Use the public IP or DNS if connecting from outside the VPC.

bash

chmod 400 mykey.pem
ssh -i mykey.pem [e-mail]

Quick Reference

Step	Action
1	Set key file permissions: chmod 400 key.pem
2	Find instance public DNS or IP
3	Use correct username (ec2-user, ubuntu, etc.)
4	Run SSH command: ssh -i key.pem username@public-dns
5	Ensure security group allows port 22 inbound

Key Takeaways

Use the SSH command with the -i option to specify your private key file.

Set your private key file permissions to 400 to keep it secure.

Use the correct username for your EC2 instance's operating system.

Make sure your EC2 security group allows inbound SSH traffic on port 22.

Connect using the instance's public DNS or IP address from outside the VPC.