instalar ssh en ubuntu server 20.04

admin3 April 2024Last Update :

Mastering SSH Installation on Ubuntu Server 20.04: A Comprehensive Guide

instalar ssh en ubuntu server 20.04

Welcome to the definitive guide on installing and configuring Secure Shell (SSH) on Ubuntu Server 20.04. As businesses increasingly move towards cloud computing and remote server management, the ability to securely access and control servers over an unsecured network has become paramount. SSH is a protocol that provides a secure channel over an unencrypted network, making it an essential tool for system administrators and IT professionals. This article will delve into the intricacies of setting up SSH on your Ubuntu server, ensuring you have a robust and secure connection to manage your server’s operations remotely.

Understanding SSH and Its Importance

Before we embark on the installation process, let’s understand what SSH is and why it’s so crucial in today’s digital landscape. SSH, or Secure Shell, is a cryptographic network protocol used for operating network services securely over an unsecured network. It provides a secure channel over which you can run a shell on a remote machine and transfer files between different machines. With the rise of cyber threats, SSH has become an indispensable tool for protecting sensitive data during remote administration.

Prerequisites for Installing SSH on Ubuntu Server 20.04

To ensure a smooth installation process, there are a few prerequisites you need to have in place:

  • A running instance of Ubuntu Server 20.04
  • Access to a user account with sudo privileges
  • An active internet connection

Step-by-Step Guide to Installing OpenSSH Server

Now, let’s dive into the step-by-step process of installing the OpenSSH server on your Ubuntu system.

Updating Your System Packages

Firstly, it’s always good practice to update your package list to ensure you’re installing the latest version of software available. Run the following command:

sudo apt update

Installing the OpenSSH Server Package

With your packages updated, you can now install the OpenSSH server package by executing:

sudo apt install openssh-server

Once the installation is complete, the SSH service will start automatically. You can verify this using:

sudo systemctl status ssh

Configuring SSH for Enhanced Security

After installation, it’s vital to configure SSH to tighten security measures. The main configuration file for SSH is located at /etc/ssh/sshd_config. You can edit this file using your preferred text editor, such as nano or vim:

sudo nano /etc/ssh/sshd_config

Here are some recommended changes:

  • Change the default SSH port (Port 22) to a non-standard port.
  • Disable root login by setting PermitRootLogin no.
  • Allow only specific users by adding AllowUsers username.

After making these changes, restart the SSH service to apply them:

sudo systemctl restart ssh

Connecting to Your Server via SSH

With SSH installed and configured, you can connect to your server from a remote machine. Use the following command:

ssh username@your_server_ip -p port_number

Replace username with your actual username, your_server_ip with your server’s IP address, and port_number with the new SSH port number if you changed it from the default.

Securing SSH Access with Key-Based Authentication

Password-based authentication is vulnerable to brute-force attacks. A more secure method is key-based authentication, which uses a pair of cryptographic keys:

Generating the SSH Key Pair

On your local machine, generate a new SSH key pair with:

ssh-keygen

This will create a private key (id_rsa) and a public key (id_rsa.pub).

Copying the Public Key to Your Server

You can copy the public key to your server using the ssh-copy-id utility:

ssh-copy-id -i ~/.ssh/id_rsa.pub username@your_server_ip -p port_number

After copying the key, you should be able to log in without a password.

Enhancing SSH Security Further

Beyond basic configurations, consider implementing additional security measures such as:

  • Setting up a firewall to restrict access to the SSH port
  • Using fail2ban to protect against brute-force attacks
  • Regularly updating your server’s software to patch vulnerabilities

Troubleshooting Common SSH Issues

If you encounter issues while connecting via SSH, check the following:

  • The SSH service is running on your server
  • Your firewall settings allow traffic on the SSH port
  • Your client’s IP is not blocked by fail2ban or similar software

Frequently Asked Questions

How do I change the SSH port on Ubuntu Server 20.04?

Edit the /etc/ssh/sshd_config file and change the line that reads Port 22 to your desired port number. Then, restart the SSH service.

Can I disable password authentication completely?

Yes, after setting up key-based authentication, you can disable password authentication by changing PasswordAuthentication yes to PasswordAuthentication no in the /etc/ssh/sshd_config file.

What should I do if I’m locked out of my server?

If you’re locked out due to SSH misconfiguration, you may need to access your server through a console provided by your hosting provider or use a physical connection if possible.

Conclusion

Installing and securing SSH on Ubuntu Server 20.04 is a critical task for anyone managing servers. By following this comprehensive guide, you’ve learned how to set up SSH, secure it with key-based authentication, and implement additional security practices. Remember, maintaining a secure SSH setup is an ongoing process that involves regular updates and vigilance against emerging threats.

References

For further reading and advanced configurations, refer to the official Ubuntu documentation and OpenSSH man pages:

By staying informed and proactive, you can ensure that your Ubuntu Server remains a stronghold against unauthorized access, safeguarding your valuable data and resources.

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