Free SSH Servers: Security Risks

TL;DR

Using a free SSH server can be risky. They often have weak security, are overloaded, or may even contain malicious software. It’s generally better to set up your own SSH server or use a reputable paid service.

Why Free SSH Servers Are Risky

Free SSH servers seem attractive – quick access without cost. However, they come with significant downsides. Here’s what you need to know:

1. Security Concerns: Many free providers don’t invest in proper security measures.
   • Weak Passwords: They might use default or easily guessable passwords.
   • Outdated Software: The SSH software itself could be old and have known vulnerabilities.
   • Compromised Servers: The server may already be infected with malware, putting your data at risk.
2. Overloading & Unreliability: Free servers are often shared by many users.
   • Slow Speeds: Performance can be very slow and unpredictable.
   • Frequent Disconnections: You might experience frequent drops in connection.
   • Limited Resources: They may restrict bandwidth or processing power.
3. Privacy Issues: The provider could be logging your activity.
   • Data Collection: Some providers collect and sell user data.
   • Lack of Transparency: It’s often unclear what data they are collecting or how it’s used.
4. Malicious Intent: Some free SSH servers are run by attackers.
   • Man-in-the-Middle Attacks: They could intercept your traffic to steal credentials or sensitive information.
   • Backdoors: The server might contain backdoors allowing unauthorized access to your system.

How to Check if an SSH Server is Secure (If You Must Use One)

If you absolutely have to use a free SSH server, take these steps to minimise the risk:

1. Change the Default Password: Immediately change any default password provided.

   ssh user@server_address

   passwd

   Choose a strong, unique password.

2. Check SSH Version: Verify the server is running a recent version of OpenSSH.

   ssh -V

   Anything older than 8.0 should be avoided if possible.

3. Disable Password Authentication (If Possible): Use SSH keys instead for stronger security.
   • Generate a key pair on your local machine:

     ssh-keygen -t rsa -b 4096

   • Copy the public key to the server’s ~/.ssh/authorized_keys file. Use ssh-copy-id user@server_address if available, or manually copy and paste it.
   • Edit the SSH configuration file (usually /etc/ssh/sshd_config) on the server to disable password authentication:

     PasswordAuthentication no

   • Restart the SSH service:

     sudo systemctl restart sshd

4. Use a Strong Firewall: Configure a firewall (like ufw on Linux) to restrict access to only necessary ports.

   sudo ufw enable

   sudo ufw allow ssh

5. Monitor Logs: Regularly check the SSH logs for suspicious activity (usually in /var/log/auth.log or similar).

Better Alternatives

These options are much safer than using a free SSH server:

• Set Up Your Own Server: The most secure option is to set up your own SSH server on a cloud provider (like DigitalOcean, AWS, or Linode) or on your own hardware.
• Reputable Paid Services: Consider using a paid SSH service from a well-known and trusted provider. They typically offer better security, reliability, and support.