Have you ever wondered how to access your server securely from anywhere in the world? SSH is the answer. But how can we ensure that this connection is secure? Keep reading to find out.

Secure Shell (SSH) is a network protocol that lets users connect securely to a remote server. It is widely used to administer servers and transfer files securely over the internet. However, exposing SSH to the internet can be risky if you do not take the proper precautions. In this article, we will guide you step by step through securely exposing SSH to the internet. We previously discussed SSH in another article, so you may also want to read this article to get started.

1. Configure a Firewall

The first crucial step is to configure a firewall to protect your server. A firewall acts as a barrier between your server and the outside world, controlling which traffic can enter and leave. On Linux systems, you can use iptables to configure firewall rules. For example:

sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT

This rule allows incoming traffic on port 22, the default SSH port.

2. Use SSH Keys

Instead of relying on passwords, use SSH keys to authenticate connections. SSH keys provide a more secure authentication method and are harder to compromise than passwords. Here is an example of generating an SSH key pair:

ssh-keygen -t rsa -b 4096

This command generates a public and private key pair.

3. Configure the sshd_config File

The main SSH configuration file is sshd_config. Here you can adjust different security options, such as restricting access to certain users or groups and disabling root access. For example, to disable root access, set:

PermitRootLogin no

4. Limit Connection Attempts

Configure your server to limit the number of failed connection attempts. This can help prevent brute-force attacks. In the sshd_config file, set:

MaxAuthTries 3

5. Monitor Logs

Keep a record of connection attempts, successful logins, and suspicious activity in your logs. This allows you to detect possible attacks and take preventive action. For example, you can review the authentication log:

tail -f /var/log/auth.log

6. Update the Software

Make sure that all security updates are installed on your operating system and on the SSH software you use.

7. Use a VPN Server

Another option is to configure a VPN (Virtual Private Network) server to access your internal network securely and then connect to the SSH server through the VPN. We have discussed various VPN-related topics in this article and this one.

8. Use Security Tools

Consider using additional security tools such as fail2ban, which monitors failed connection attempts and blocks source IP addresses after a certain number of attempts.

Summary

Exposing SSH to the internet securely requires a combination of security configurations and good practices. From configuring a firewall to using SSH keys and limiting connection attempts, every step helps protect your server. Always keep your system up to date and watch for suspicious activity in your logs. You are now ready to access your server securely from anywhere in the world.