How to Fix "Connection Refused" Error

The "connection refused" error is something many of us run into when trying to access websites, services, or servers over a network. Essentially, this error means that the client - whether it's your browser or an application - was unable to connect to the target host, which simply "refused" the connection attempt. For system administrators, developers, and users alike, it's important to understand what causes this issue and how to resolve it effectively. In this article, we’ll dive into the various reasons behind the "connection refused" error, explore the different scenarios in which it can occur, and discuss solutions from both the client-side and server-side perspectives.

 

 

 

 

 

What does the Connection Refused error mean in simple terms?

The Connection Refused error means that the computer or server you are trying to connect to exists and is responding, but is not accepting your connection. It's like when you make a phone call and the person on the other end picks up the phone but immediately puts it back down.

This behavior indicates that the connection is physically possible, but either the service is not listening to the required port, or a firewall is blocking the attempt.

 

 

 

 

Understanding the Connection Refused Error

The "connection refused" error message can appear in different formats across platforms and tools, such as:

    ERR_CONNECTION_REFUSED  - in web browsers;
    Connection refused - in command-line tools like curl or telnet;
    Site refused to connect - in browsers when a website is inaccessible.

These messages mean that the target machine or server is reachable but refuses to allow the connection request. This typically happens when the server or port is not listening, a firewall blocks the request, or the connection configuration is misconfigured.

In technical terms, when a client sends a connection request via a protocol (e.g., HTTP, SSH, etc.), it passes through multiple layers (network stack, firewall, etc.) before reaching the application. If the connection is denied at any point, the client receives a "connection refused" message.

 

 

 

Common Causes of the "Connection Refused" Error

 

Several factors can cause a "connection refused" error. These issues can occur on the client, server, or network level. Let's explore the common causes:

Server-Side Issues

• Service Not Running: If the service you are trying to connect to (e.g., a web server, SSH server, or database) is not running on the server, the client will encounter a connection refused error.
• Port Not Listening: Even if the service is running, the specific port might not be open or listening for incoming connections. This often occurs when the service is misconfigured or bound to the wrong IP address.
• Server Overload: A server may refuse new connections if it is under heavy load or has reached its connection limit.
• Firewall Blocking: A firewall (local or network-based) could block incoming connections on the port, leading to a refused connection error.
• Misconfiguration in Server Settings: Incorrect settings in the service configuration (such as Apache, NGINX, or SSHD) may prevent the server from properly handling connection requests.   

 

Client-Side Issues

• Incorrect IP or Port: If the client is trying to connect to the wrong IP address or port, the server might not accept the connection.
• DNS Resolution Issues: If the DNS cannot resolve the server’s IP address properly, the client will be unable to reach the server, leading to a connection refused error.
• Network Connectivity Problems: Poor network connectivity or router/firewall settings on the client side could also cause this issue.
• Outdated Client Software: Sometimes, outdated client software might not support the necessary protocols or security features required by the server, leading to failed connections.

   
   
Network Issues

• Routing Problems: Incorrect routing in the network can cause connection requests to be dropped or denied.
• Network Address Translation (NAT) Issues: Misconfigured NAT can prevent the server from properly accepting incoming connections.

   
   

 

 

How to identify the source of the error

Before proceeding with active diagnostics, it is important to understand at what level the failure occurs - on the client side, the server side, or the network itself. This will help you avoid chaotic checks and immediately choose the right direction for analysis.

• The server does not respond at all - the most common situation is when the service is not running, the port is not listening, or the connection is blocked by a firewall.
• The server responds, but the connection closes immediately - there may be an error in the application configuration, protocol mismatch, connection limit, or request filtering at the server level.
• The error occurs periodically - most likely, the problem is with the network: router overload, unstable NAT, or temporary restrictions on the part of the provider.
• The deviation is observed only with individual clients - it is worth checking the local firewall, DNS cache, and the correctness of the IP/port.

To identify the source, use basic utilities (ping, traceroute, telnet, ss, ufw status, etc.), each of which shows the connection status at its own level.

The following section provides specific examples and commands for diagnostics on the server, client, and network sides, as well as a table that will help you quickly determine where the failure is occurring.

 

 

 

Diagnosing the "Connection Refused" Error

 

Before fixing the issue, it is important to accurately diagnose where the connection failure occurs. Here are several steps you can take to identify the root cause:

 

• Check Server Status

Verify Service Status: Use tools like systemctl or service (Linux) to check whether the required service is running:

      systemctl status apache2
    systemctl status ssh

 

Check Port Listening: Use netstat or ss to check whether the specific port is open and listening:

    ss -tuln | grep :80

If the port is not open, the server will refuse to connect.

 

• Firewall and Network Configuration

Check Firewall Rules: On the server, use iptables or firewall management tools (such as firewalld, ufw, or Windows Firewall) to ensure that the port is not being blocked:

    sudo ufw status
    sudo iptables -L

Ensure the firewall allows incoming connections on the required port.

 

Traceroute/Tracerpath: Use traceroute or tracerpath to check if packets are correctly routed to the target server:

    traceroute example.com

 

 

• Client-Side Diagnostics

Check IP and Port: Ensure that the client is connecting to the correct IP address and port by cross-checking the configuration file or connection settings.
DNS Lookup: Perform an nslookup or dig query to ensure the domain name resolves correctly:

    nslookup example.com
    dig example.com

 

Check for Browser Cache Issues: Sometimes browser caching can lead to persistent "connection refused" errors. Clearing the cache and trying again may solve the issue.

 

• Network-Level Testing

Telnet Test: Use telnet to test the connection to the server. This helps determine if the issue is network-related or service-related:

    telnet example.com 80

If the connection is refused, the problem lies in the server configuration or network settings.

 

Table: Identifying the Source of the Connection Refused Error

Symptom	Possible Cause	Level	Command / Tool	Next Step / Recommendation
Server does not respond, connection immediately refused	Service is stopped or crashed	Server	systemctl status nginx or systemctl status ssh	Restart the service and check logs: journalctl -u <service>
Port closed or not listening	Application not bound to correct address or port	Server	`ss -tuln | grep :80`	Restart the service that should listen on the port
Firewall blocking connection	Incorrect iptables, ufw, or firewalld rules	Server	sudo ufw status or sudo iptables -L -n -v	Allow required port: sudo ufw allow 80/tcp
Connection succeeds but immediately closes	Application misconfiguration or connection limit reached	Server	sudo tail -n 50 /var/log/nginx/error.log	Fix configuration and restart the service
Unable to resolve domain name	DNS misconfiguration or invalid record	Client	dig example.com or nslookup example.com	Update DNS servers or /etc/resolv.conf file
Connection works from one network but not another	Routing, NAT, or ISP filtering issues	Network	traceroute example.com	Check router/NAT settings or use VPN
Error occurs intermittently	Server overload or temporary network instability	Network / Server	mtr example.com or ping -c 10 example.com	Check load and network stability
Only one client affected	Local firewall or antivirus blocking outgoing traffic	Client	sudo iptables -L or antivirus rule check	Allow connection or add firewall exception

These checks help you quickly identify whether the Connection Refused error originates from the client, server, or network layer before applying specific fixes.

 

 

Fixing the "Connection Refused" Error: Server-Side Solutions

Once the cause has been identified, you can implement the appropriate solution. Let’s explore how to fix the error depending on the situation.

 

• Ensure the Service is Running

If the server’s required service (such as HTTP or SSH) is not running, restart the service:

    sudo systemctl restart apache2
    sudo systemctl restart ssh

If the service fails to start, check the logs in /var/log/ or the service-specific log directory for more detailed error messages.

 

• Open the Required Port

Ensure that the server is listening on the required port. Edit the configuration files (e.g., /etc/apache2/ports.conf for Apache) to ensure the correct port is bound. Restart the service after making changes.

For example, if the server is supposed to listen on port 8080 but is not, you can manually edit the port settings:

    Listen 8080

 

• Update Firewall Rules

Open the necessary port using ufw or other firewall management tools:

    sudo ufw allow 80/tcp
    sudo ufw allow 443/tcp

For iptables, you might need to add a rule to accept connections on the port:

    sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT

 

• Check for Application-Specific Issues

For web applications running on servers like NGINX or Apache, misconfigurations in virtual hosts or reverse proxy settings can lead to the server refusing connections. Double-check the configuration files (e.g., /etc/nginx/nginx.conf) and make sure there are no syntax errors:

    sudo nginx -t
    sudo apachectl configtest

Correct any issues found in these configuration files and restart the service.

 

 

 

Client-Side Solutions for "Connection Refused" Error

 

The "connection refused" error could also stem from the client side. Here’s how to fix common client-side issues.

 

• Verify Connection Details

Ensure the client is connecting to the correct IP address, hostname, and port. Double-check the client application’s settings, especially when dealing with services like SSH, FTP, or web applications.

• Clear Browser Cache

If you encounter the "ERR_CONNECTION_REFUSED" message in a browser, clearing the browser cache and cookies may resolve the problem. Navigate to the browser settings, clear the cache, and attempt to reconnect.

• Network and DNS Configuration

If the issue stems from DNS resolution failures, you can change the DNS settings to use a public DNS like Google (8.8.8.8) or Cloudflare (1.1.1.1). This can be done either on the client machine or router.

 

 

 

Handling Network-Level Issues

 

Network issues such as incorrect routing, NAT misconfigurations, or ISP blocks can also cause connection refused errors. Here’s how to resolve such issues:

• Check Router and Firewall Settings

Ensure that your router is forwarding the correct ports if the server is behind a NAT. Open ports as required and verify that the firewall does not block them.

• Use a VPN

If the error occurs due to geographical restrictions or ISP blocks, using a VPN can help bypass these restrictions and connect to the server.

 

 

 

How to Prevent the Connection Refused Error in the Future

 

Once the problem is resolved, it’s important not only to restore connectivity but also to prevent the Connection Refused error from reoccurring. Regular monitoring and basic automation help detect issues early and reduce the risk of service downtime.

 

Set up port and service monitoring

Use monitoring tools such as Netdata, Prometheus, Zabbix, or Uptime Kuma to track the availability of ports, services, and network connections.
These tools can alert you in real time about service failures, blocked ports, or overload conditions, allowing you to fix issues before they affect users.

 

Automate service restarts

For system daemons and network services, configure automatic recovery using the Restart=always directive in systemd unit files.
This ensures that the service will restart automatically after a crash or update.

Example:

     [Service]
     ExecStart=/usr/bin/myservice
     Restart=always
     RestartSec=5 

 

Keep your system and DNS cache up to date

Regular security updates and library upgrades minimize compatibility issues.
Clearing and refreshing the DNS cache helps avoid failed connections due to outdated domain records.

 

Add an automatic connection check

You can create a simple cron job to periodically test port availability and log the results. This is particularly useful for web servers and APIs:

     */10 * * * * nc -zv your-server.com 80 >> /var/log/conn_check.log 2>&1

 

This command runs every 10 minutes, checks connectivity to port 80, and logs the result to /var/log/conn_check.log.
You can expand it to monitor multiple ports or hosts if needed.

 

Recommended monitoring tools

Tool	Purpose	Key Features
Netdata	Real-time server and port monitoring	Easy setup, automatic metrics
Prometheus	Metrics collection with Grafana integration	Ideal for clusters and containers
Zabbix	Full infrastructure monitoring	Flexible triggers and alerts
Uptime Kuma	HTTP/HTTPS and TCP uptime tracking	User-friendly web interface, graphs
Monit	Local process and service supervision	Can restart failed services automatically

 

 

 

 

Conclusion

The "connection refused" error can arise from a variety of issues on both the client and server sides. By methodically diagnosing the problem through service status checks, firewall configurations, and network tests, you can identify the root cause and apply the appropriate fixes. Whether it’s a misconfigured server, network issues, or a simple client-side mistake, understanding the potential reasons behind a refused connection will help in resolving the issue efficiently.