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How To Fix SSH Connection Refused Errors in Ubuntu Server

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Secure Shell (SSH) is a crucial tool for administrators and developers alike, providing a secure way to access remote servers. However, it’s not uncommon to encounter an SSH “Connection refused” error when attempting to connect to an Ubuntu server. This article will guide you through several methods to resolve this issue.

1. Installing openssh-server

The first step is to ensure that the openssh-server package is installed on your Ubuntu server. This package is necessary for the server to accept SSH connections. Use the following command to install it:

sudo apt-get install openssh-server openssh-client

The sudo command is used to run the command as a superuser. The apt-get install command is used to install packages, and openssh-server and openssh-client are the packages we’re installing.

2. Checking IP Address Conflicts

IP address conflicts can cause connection issues. Use tools like arp-scan to check if multiple devices are claiming the same IP address. If conflicts are found, resolve them by assigning unique IP addresses to each device.

3. Checking Firewall Settings

Firewalls can often block SSH connections. To check if this is the case, you can temporarily disable the firewall and see if the issue persists. If it does not, you will need to adjust the firewall settings to allow SSH connections. The exact process for this will depend on the firewall software you’re using.

4. Checking SSH Configuration

The SSH configuration file on your server could be another source of the problem. Use the following command to open the file in a text editor:

sudo nano /etc/ssh/ssh_config

In this command, nano is a text editor, and /etc/ssh/ssh_config is the path to the SSH configuration file.

Look for the line that specifies the port number for SSH (usually port 22). If it’s commented out (i.e., preceded by a ‘#’), uncomment it by removing the ‘#’ symbol. Save the file and restart the SSH service with the following command:

sudo service sshd restart

5. Checking for Network Equipment Issues

If the problem persists, it could be due to issues with your network equipment. Check the logs on your server for any ethernet link up/down events. If you find any, try changing the cables or restarting your network equipment.

6. Checking for IPTables Rules

If you have IPTables rules set up on your server, these could be limiting new SSH connections. Use the following command to view the rules:

sudo iptables -n -L

If any rules are found that limit new SSH connections, adjust or remove them to allow more connections.

7. Checking for fail2ban

If you have fail2ban installed on your server, it may have banned your IP address. Use the following command to check if your IP is banned:

sudo iptables -n -L

If your IP address is in the banned list, you can unban it using the fail2ban command or by following the instructions provided in the fail2ban documentation.

Remember to restart the SSH service after making any changes to the configuration or firewall settings.

In conclusion, resolving the “Connection refused” error in SSH connection involves checking and adjusting several settings related to your network, firewall, and SSH configuration. By following these steps, you should be able to successfully connect to your Ubuntu server via SSH.

What is SSH?

SSH stands for Secure Shell and is a cryptographic network protocol that allows secure communication between two computers. It provides a secure way to access and manage remote servers.

Why am I getting a “Connection refused” error when trying to connect to my Ubuntu server via SSH?

The "Connection refused" error typically occurs when the SSH server on your Ubuntu server is not running or is not configured correctly. There can be various reasons for this, such as the SSH server not being installed, firewall settings blocking SSH connections, or incorrect SSH configuration.

How do I install openssh-server on my Ubuntu server?

To install openssh-server, use the following command: sudo apt-get install openssh-server openssh-client. This command will install both the server and client components required for SSH connections.

How can I check if there are IP address conflicts causing the SSH connection issue?

You can use tools like arp-scan to check if multiple devices on your network are claiming the same IP address. If conflicts are found, you will need to assign unique IP addresses to each device to resolve the issue.

How can I temporarily disable the firewall to check if it’s causing the SSH connection issue?

The process for temporarily disabling the firewall depends on the firewall software you’re using. Generally, you can use commands like sudo ufw disable or sudo systemctl stop firewalld to disable the firewall. Remember to enable the firewall again after testing.

How do I edit the SSH configuration file?

You can edit the SSH configuration file using a text editor like nano. Use the command sudo nano /etc/ssh/ssh_config to open the file. Look for the line that specifies the port number for SSH (usually port 22) and make any necessary changes. Save the file and restart the SSH service.

What should I do if my IP address is banned by fail2ban?

If your IP address is banned by fail2ban, you can unban it using the fail2ban-client set <jail-name> unbanip <your-ip-address> command. Replace <jail-name> with the name of the fail2ban jail and <your-ip-address> with your actual IP address. Alternatively, you can refer to the fail2ban documentation for specific instructions on how to unban an IP address.

Do I need to restart the SSH service after making changes to the configuration or firewall settings?

Yes, it is recommended to restart the SSH service after making any changes to the SSH configuration file or firewall settings. You can use the command sudo service sshd restart to restart the SSH service on your Ubuntu server.

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