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Accessing and Verifying an Instance

This document explains how to connect to a newly created instance and check its operational status.
After launching an instance, you can verify its proper operation and perform initial configuration tasks.

Establishing SSH Connection

Verify the Key Pair File

SSH 접속 준비
  • Open the terminal and navigate to the directory where the downloaded key pair file (*.pem or id_rsa) is located.
    • ls -al | grep *.pem
    • ls -al | grep id_rsa
SSH 접속 실행

Connect to the Instance via SSH

  • Command:ssh -i [keypair_file].pem [username]@[external_IP]
  • Example: ssh -i test.pem ubuntu@192.168.103.91

Terminate SSH Session

  • Type exit in the terminal to close the connection.

Checking System Status

Once connected to the instance, you can use the following commands to verify the system specifications and status.

Check Basic System Information

cmd_release
  • Operating System Info: cat /etc/os-release

Check System Resources

cmd_df
  • Disk Usage: df -h
  • Memory Usage: free -h

Check Network Connection

cmd_ip
  • External IP Check: curl ifconfig.co

Troubleshooting SSH Connection Failures

If SSH connection fails, check the following items.

Key File Issues

  • Confirm that the key file exists
  • Ensure the correct file path is used
  • Check permission settings (must be 400)
    • To change permissions: chmod 400 keypair_file.pem

Network Issues

  • Make sure SSH port (22) is open in the security group
  • Confirm that an external IP is assigned and reachable
  • Check that the instance is currently running