Connecting to a Cloud Server

Cloud servers (Virtual Private Servers, or VPS) let you run applications and websites on remote infrastructure without managing physical hardware. This guide covers the three most common ways to connect to a cloud server — SSH (Linux/Mac command line), PuTTY (Windows GUI), and Remote Desktop (Windows servers) — and how to keep your connection secure.

1. What You Need Before Connecting

Gather the following before attempting a connection:

• Server IP address: Provided by your cloud provider (e.g., AWS, DigitalOcean, Vultr, Linode) in the instance dashboard.
• Username: Typically root (initial setup), ubuntu (Ubuntu servers on AWS/DigitalOcean), or ec2-user (Amazon Linux).
• Authentication method: Either an SSH key pair (recommended) or a password set during server creation.
• SSH port: Default is port 22. Some providers or admins change this for security — confirm with your provider.
• Firewall rules: Ensure port 22 (SSH) or 3389 (RDP) is open in your cloud provider's security group or firewall rules.

2. Connecting via SSH (Linux / macOS)

Open the Terminal and run:

# Using an SSH key
ssh -i /path/to/your-key.pem username@SERVER_IP

# Using a password (less secure)
ssh username@SERVER_IP

Replace username with your actual username and SERVER_IP with the IP address from your cloud dashboard.

On first connection, you will see a host key warning:

The authenticity of host '203.0.113.10' can't be established.
ECDSA key fingerprint is SHA256:abc123...
Are you sure you want to continue connecting (yes/no)?

Type yes and press Enter. The host key is saved to ~/.ssh/known_hosts. If you see this warning again for a server you've already connected to, it may indicate a man-in-the-middle attack — verify the server's IP has not changed before proceeding.

3. Connecting via SSH on Windows

Windows 10 and later include a built-in OpenSSH client. Open PowerShell or Command Prompt and use the same syntax as above:

ssh -i C:\Users\YourName\.ssh\your-key.pem username@SERVER_IP

Alternatively, use PuTTY for a graphical interface:

1. Download and install PuTTY from the official PuTTY website.
2. If you have a .pem key, open PuTTYgen, load the key, and save it as a .ppk file.
3. Open PuTTY, enter your server IP in "Host Name", set port to 22, and connection type to SSH.
4. Go to Connection → SSH → Auth → Credentials and browse to your .ppk file.
5. Click Open, accept the host key warning, and enter your username when prompted.

4. Connecting to a Windows Server via RDP

If your cloud server runs Windows Server, use Remote Desktop Protocol (RDP):

1. Open Remote Desktop Connection (search "mstsc" in the Start menu).
2. Enter your server IP address in the "Computer" field.
3. Click Show Options → enter your username (e.g., Administrator).
4. Click Connect and enter the password when prompted.
5. Accept the certificate warning on first connection.

From macOS, download Microsoft Remote Desktop from the Mac App Store and follow a similar process.

5. Setting Up SSH Key Authentication

SSH key authentication is more secure than passwords. Here is how to set it up:

# 1. Generate a key pair on your local machine
ssh-keygen -t ed25519 -C "your@email.com"

# 2. Copy your public key to the server
ssh-copy-id username@SERVER_IP

# 3. Test the key-based login
ssh username@SERVER_IP

After confirming key-based login works, disable password authentication on the server:

# Edit /etc/ssh/sshd_config on the server
PasswordAuthentication no

# Restart SSH service
sudo systemctl restart sshd

6. Security Best Practices

• Change the default SSH port: Change from 22 to a non-standard port (e.g., 2222) in /etc/ssh/sshd_config to reduce automated scanning attacks.
• Disable root login: Set PermitRootLogin no in sshd_config. Create a separate sudo user for administration.
• Use Fail2Ban: Install Fail2Ban to automatically block IP addresses after repeated failed login attempts.
• Keep your keys safe: Never share your private key. Store it in ~/.ssh/ with 400 permissions. Back up to an encrypted location.
• Use firewall rules: Restrict SSH access to your office IP range via your cloud provider's security group — do not leave port 22 open to the entire internet.

7. Troubleshooting Connection Issues