TL;DR
To install OpenSSH on Ubuntu and enable it, you can follow these steps:
- Check if OpenSSH is already installed using the command:
dpkg -l | grep openssh-server. - If OpenSSH is not installed, update the package list with:
sudo apt updateand install OpenSSH server with:sudo apt install openssh-server. - Start the OpenSSH service:
sudo systemctl start ssh. - Optionally, enable automatic start at boot:
sudo systemctl enable ssh. - Allow SSH traffic through the firewall using the command
sudo ufw allow ssh.
Continue reading the guide below to learn to install OpenSSH on Ubuntu and Enable It. Also learn the benefits and common errors of installing and enabling OpenSSH.
Setting up secure remote access to your server can be tricky, especially if you’re new to Linux. Don’t worry, though—OpenSSH is here to help. In this post, I’ll guide you through installing and enabling OpenSSH on Ubuntu, making it easy for you to securely access and manage your remote servers. You’ll find a detailed, step-by-step guide that covers everything from installation to firewall adjustments and troubleshooting common errors. By the end, you’ll have a secure and reliable remote access setup on your Ubuntu system. Let’s get started!
What is OpenSSH?
OpenSSH, or Open Secure Shell, is a set of tools that provide secure access to remote computers. It allows you to log into another computer, transfer files, and execute commands securely over an insecure network, like the internet.
Importance of OpenSSH in the Linux Ecosystem
OpenSSH is crucial in the Linux ecosystem for several reasons:
- Secure Remote Access: Administrators and users can securely access and manage remote servers.
- File Transfers: It supports secure file transfer protocols (SCP and SFTP) to move files between computers safely.
- Tunneling: OpenSSH can create secure tunnels for other types of network traffic, adding an extra layer of security to applications.
- Portability and Compatibility: OpenSSH is available on almost all Unix-like systems, including Linux, making it a standard tool for remote management.
Key Features and Benefits of Using OpenSSH
- Encryption: Protects data with strong encryption algorithms, keeping it safe from interception.
- Authentication: Supports various methods of authentication, including passwords and public keys, ensuring only authorized users gain access.
- Port Forwarding: Enables secure forwarding of network traffic, which helps protect data when using less secure applications.
- Simplicity and Flexibility: Easy to install and configure, suitable for both simple and complex network setups.
- Open Source: Free to use and modify, with regular updates and strong community support, ensuring it stays secure and up-to-date.
How to Install OpenSSH on Ubuntu and Enable It
To install OpenSSH on Ubuntu and enable it, first open your terminal and update your package list with sudo apt update. Next, install the OpenSSH server package using sudo apt install openssh-server. Start the OpenSSH service with sudo systemctl start ssh and enable it to start on boot with sudo systemctl enable ssh. Adjust your firewall to allow SSH connections by running sudo ufw allow ssh. Verify the status with sudo systemctl status ssh and you’re all set to securely access your Ubuntu server remotely.
Here is a detailed step-by-step guide:
- Open a Terminal on your Ubuntu system.
- Enter the following command to check if OpenSSH is already installed:
dpkg -l | grep openssh-serverIf OpenSSH is already installed, you will see it listed in the output.
- If OpenSSH is not already installed, you can install it by following these steps:
- Update the package list by running the command:
sudo apt updateThe command will update the system package list.
- Install the OpenSSH server package by running the following command:
sudo apt install openssh-server- Press Enter to continue the installation.
- To start the OpenSSH service, use the following command:
sudo systemctl start sshThis command will initiate the OpenSSH service, allowing remote access to your Ubuntu system.
- To stop the OpenSSH service, use the following command:
sudo systemctl stop sshThis command will stop the OpenSSH service.
- To enable the OpenSSH service to start automatically at boot, use the following command:
sudo systemctl enable sshThis command configures the OpenSSH service to launch automatically when your Ubuntu system starts up, ensuring persistent remote access.
- To disable the automatic start of the OpenSSH service at boot, use the following command:
sudo systemctl disable sshThis command prevents the OpenSSH service from starting automatically during system boot, thereby disabling remote access by default.
- To allow SSH traffic through the firewall and ensure secure remote access, first of all check the current firewall status by running:
sudo ufw statusThis command will display the current status of the firewall.
- If the firewall is inactive, enable it by running:
sudo ufw enableThis command will activate the firewall on your system.
- Allow SSH traffic by running:
sudo ufw allow sshThis command will add a rule to allow incoming SSH connections through the firewall.
- Verify the firewall rules by running:
sudo ufw statusThis command will display the updated firewall rules, including the newly added SSH rule.
4 Common Errors When Using OpenSSH
When working with OpenSSH, encountering errors is not uncommon. However, understanding and resolving these errors is crucial to ensure a smooth and secure remote access experience. Here are four common errors you may encounter while using OpenSSH:
- 🔒 “Permission Denied (publickey)” error: This error often occurs when establishing an SSH connection using public key authentication. It indicates a problem with the SSH key setup or the permissions on the authorized_keys file. To resolve this, ensure the correct public key is configured on both the client and server, and the file permissions are correctly set.
- ⚠️ “Connection Refused” error: This error typically arises when the SSH service is not running on the remote server or is inaccessible due to firewall restrictions. Verify that the SSH service is running and properly configured on the server. Additionally, check the firewall settings to ensure the appropriate port (usually port 22) is open for SSH connections.
- 🚧 “Host Key Verification Failed” error: This error occurs when the host key of the remote server does not match the previously cached key, indicating a possible security breach or server misconfiguration. To resolve this, you can remove the cached key for the specific host or update the host key manually using the
ssh-keygencommand. - 🔌 “Connection Timed Out” error: This error typically indicates a network connectivity issue. It can be caused by firewall restrictions, incorrect network configurations, or network interruptions. Ensure that the SSH port is open, the server is accessible from the client’s network, and no network disruptions or firewall rules are blocking the connection.
In Conclusion
In this guide, I’ve walked you through the step-by-step process of installing and enabling OpenSSH on Ubuntu. You learned how to update your system, install OpenSSH, adjust firewall settings, and verify that the service is running correctly.
If you’re interested in expanding your Linux skills further, I recommend exploring articles on:
- Learning how to enable SSH on Debian if you use multiple distributions.
- Exploring how to effectively use the netcat command in Linux, which can complement your SSH usage for various network tasks.
- How to fix the “You Have Held Broken Packages” error on Linux, which can sometimes occur during installations,
Frequently Asked Questions
Can I use OpenSSH with multiple user accounts?
How can I change the default SSH port?
Changing the default SSH port adds an extra layer of security to your system. To modify the default SSH port, you need to edit the SSH configuration file located at
/etc/ssh/sshd_config. You’ll find a line inside the file specifying the current port number, typically set to 22. Simply modify this line to your desired port number, ensuring it falls within the range of valid ports (1-65535). Save the changes and restart the OpenSSH service for the new port configuration to take effect. It’s important to note that after changing the SSH port, you must specify the new port number when connecting to the server.Is it possible to disable password-based authentication and use only public keys?
/etc/ssh/sshd_config. Look for the PasswordAuthentication option and set it to no. This configuration change instructs OpenSSH to reject password-based logins, making public key authentication the only accepted method. After saving the changes, remember to restart the OpenSSH service for the new configuration to take effect. By disabling password-based authentication, you can significantly enhance the security of your SSH connections, as public key authentication offers stronger cryptographic protection.
