How to Connect to a Cumulus Server

Your Cumulus server can serve content to the Internet when you set up web services, but server access requires VPN connection.
⚠️⚠️⚠️ WARNING: This server must only be used for course activities. Unauthorized use for private projects will result in immediate loss of access and potential disciplinary action.

The SSH key you have received should be considered a secret. Never share it with third parties or display it publicly.

What is Cumulus?

Cumulus is a Linnaeus University cloud computing platform that provides virtual servers for educational and research purposes. Depending on your role and needs, you may receive a pre-configured server or create one yourself.

Each server typically includes:

• An Ubuntu Linux server running in the cloud
• Root-level access to install software and configure services
• A unique DNS name
  • cuXXXX.camp.lnu.se for university-internal or VPN-accessible servers
  • cuXXXX.cloud.lnu.se for public, internet-facing services
• Web connectivity
  • Servers connected to the Cumulus campus network are accessible from within the university network. Access from outside requires a VPN connection.
  • Servers connected to the Cumulus public network are accessible directly from the internet.
• SSH access
  • Secure remote access (via SSH) is available from the university network. A VPN connection is required when connecting from outside the university network.

What you can do with your Cumulus server:

• Deploy web applications and APIs
• Learn Linux system administration
• Practice server configuration and security
• Host course projects accessible from anywhere on the internet
• Experiment with different technologies without affecting your personal computer

Important limitations:

• Access requires connection to the university VPN
• The server is for course-related activities only - not personal projects
• Your server and data may be reset between courses
• Resource usage is monitored and limited

Think of Cumulus as your personal sandbox server where you can safely learn and experiment with real-world server technologies in a controlled environment.

Step 1: Verify SSH Availability

Before you can connect to your Cumulus server, make sure that the ssh command is available in your terminal.

Step 2: Download Your Identity File from GitLab

To access your personal server in the Cumulus cloud via SSH, you need an identity file (private key). This file is provided through a GitLab project.

Locate and download the identity file:

1. Go to the Secrets project in GitLab
2. In this project, you will find:
   • Your private key file (named something like id_cumulus_xxx)
   • The IP address of your server
   • The DNS name assigned to your server
3. Download the private key file (id_cumulus_xxx) to a known location on your computer

Keep this file safe - you'll need it in the next step.

Step 3: Create the .ssh Directory

The .ssh directory is a standard location for storing SSH keys and configuration files. If it doesn't already exist, you need to create it.

Step 4: Move the Identity File to .ssh Directory

Now you need to move the downloaded identity file to the .ssh directory.

Step 5: Set Correct Permissions on the Identity File

Setting the correct permissions ensures that your private key is only readable by you. SSH will refuse to use the key if it's accessible by others, as this would pose a security risk.

Step 6: Connect to Your Cumulus Server via SSH

Once your identity file is in place and has the correct permissions, you can connect to your personal server in the Cumulus cloud using SSH.

Find your server's address:

In the GitLab Secrets project, you will find either:

• The DNS name of your server (recommended), e.g. cuXXXX.camp.lnu.se
• Or the IP address, e.g. 172.27.XXX.XXX

Connect using SSH:

Open your terminal (Git Bash on Windows, Terminal on macOS/Linux) and run:

Replace:

• id_cumulus_xxx with the actual filename of your private key
• cuXXXX.camp.lnu.se with your server's DNS name (or IP address)

📌 Example

If this is your first time connecting, you may be asked to confirm the host's fingerprint. Type yes to continue.

🔧 Troubleshooting: Remove a Previously Registered Key

If you've connected to your server before and the host key has changed (for example, due to a reinstallation), SSH may refuse to connect and show a warning about a mismatched key.

To fix this, remove the old key from your known hosts file:

Replace cuXXXX.camp.lnu.se with your server's actual DNS name or IP address. This command deletes the outdated entry from ~/.ssh/known_hosts, allowing you to reconnect without errors.

✅ What Happens When You Successfully Connect

If the SSH connection is successful, you'll see a welcome message from the Ubuntu operating system, along with system information such as memory usage, IP address, and login history.

You will land in your home directory, typically /home/ubuntu, and the prompt will look something like:

From here, you can start working on your server — installing packages, running applications, or setting up web services.

Step 7: Update Package Lists

Before installing any software on your Cumulus server, it's good practice to update the package lists. This ensures that you get the latest available versions of packages from the Ubuntu repositories.

You are logged in as a regular user (ubuntu), so administrative commands like apt update require sudo.

Run the following command:

This command fetches the most recent information about available packages and updates, which is necessary before installing tools like Docker, Node.js, npm, and nginx.

You only need to run this once before installing multiple packages. There's no need to repeat it before each installation unless a significant amount of time has passed or you've added new repositories.