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SSH Access to Your VMs

Learn how to connect to your Linux VMs using SSH for secure command-line access.

Prerequisites​

  • VM with SSH server installed
  • VM's IP address
  • SSH credentials (username/password or SSH key)
  • VPN connection to TxCR

Finding Your VM's IP Address​

Via Xen Orchestra​

  1. Log into XO
  2. Click on your VM
  3. Look for IP addresses in the General tab

Within the VM (console)​

# Show all network interfaces
ip addr show

# Or specifically for main interface
ip addr show eth0

Connecting via SSH​

Linux / macOS​

Open Terminal and connect:

ssh [email protected]

Example:

ssh [email protected]

First connection will ask to verify fingerprint:

The authenticity of host '10.50.1.100' can't be established.
ED25519 key fingerprint is SHA256:xxxxx.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes

Type yes and press Enter.

Windows​

Option 1: Built-in OpenSSH (Windows 10/11)

ssh [email protected]

Option 2: PuTTY

  1. Download PuTTY
  2. Run PuTTY
  3. Enter hostname/IP
  4. Port: 22
  5. Connection type: SSH
  6. Click "Open"
  7. Enter username and password

Generate SSH Key Pair​

Linux/macOS:

ssh-keygen -t ed25519 -C "[email protected]"

Windows (PowerShell):

ssh-keygen -t ed25519 -C "[email protected]"

Save to default location and optionally set a passphrase.

Copy Public Key to VM​

Method 1: ssh-copy-id (Linux/macOS)

ssh-copy-id [email protected]

Method 2: Manual

# Display your public key
cat ~/.ssh/id_ed25519.pub

# SSH into VM and add to authorized_keys
mkdir -p ~/.ssh
chmod 700 ~/.ssh
echo "your-public-key-here" >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Connect with Key​

ssh -i ~/.ssh/id_ed25519 [email protected]

SSH Config for Easy Access​

Create ~/.ssh/config:

Host txcr-vm1
    HostName 10.50.1.100
    User alex
    IdentityFile ~/.ssh/id_ed25519
    
Host txcr-vm2
    HostName 10.50.1.101
    User admin
    IdentityFile ~/.ssh/id_ed25519

Now connect simply:

ssh txcr-vm1

File Transfer via SCP/SFTP​

SCP Examples​

Copy file TO server:

scp localfile.txt [email protected]:/remote/path/

Copy file FROM server:

scp [email protected]:/remote/file.txt ./local/path/

Copy directory recursively:

scp -r local/directory [email protected]:/remote/path/

SFTP Session​

sftp [email protected]

SFTP commands:

  • ls - list remote files
  • lls - list local files
  • cd - change remote directory
  • lcd - change local directory
  • get file.txt - download file
  • put file.txt - upload file
  • exit - quit

Troubleshooting​

Connection Refused​

Check:

  • VPN is connected
  • SSH service is running: sudo systemctl status sshd
  • Firewall allows port 22: sudo firewall-cmd --list-all
  • Correct IP address

Permission Denied​

Verify:

  • Correct username
  • Correct password
  • SSH key permissions (600 for private key, 644 for public)
  • User account is not locked

Timeout​

  • Check VM is running
  • Verify network connectivity: ping 10.x.x.x
  • Check routing

Security Best Practices​

✅ Do:

  • Use SSH keys instead of passwords
  • Disable root login
  • Change default SSH port (optional)
  • Use strong passphrases
  • Keep SSH client/server updated

❌ Don't:

  • Use weak passwords
  • Share private keys
  • Allow password authentication for root
  • Expose SSH to untrusted networks

Disable Password Authentication​

After setting up keys:

Edit /etc/ssh/sshd_config:

PasswordAuthentication no
PubkeyAuthentication yes

Restart SSH:

sudo systemctl restart sshd

Next Steps​

See also: FAQ | Troubleshooting