Linux Connection Refused

The 'Connection Refused' error (often associated with errno 111, ECONNREFUSED) indicates that a TCP connection request was actively rejected by the remote host's kernel. This typically means nothing is listening on the specified IP address and port.

Common Causes

The target service (e.g., SSH, web server) is not running on the remote host.
The service is bound to a different IP address (like 127.0.0.1) instead of the network interface you are trying to reach.
A host-based firewall (iptables, firewalld, ufw) is blocking the connection to the specific port.

How to Fix

1 Check Service Status and Port Binding

Verify the target service is running and listening on the correct network interface and port.

BASH

 $ # Check if a service like sshd is running
sudo systemctl status sshd

# Use netstat or ss to see listening ports
sudo ss -tlnp | grep :22
# Or
sudo netstat -tlnp | grep :22

2 Inspect and Configure Host Firewall

Check if a local firewall is blocking the port and add a rule to allow traffic if necessary.

BASH

 $ # For firewalld (RHEL/CentOS/Fedora)
sudo firewall-cmd --list-all
sudo firewall-cmd --add-service=ssh --permanent
sudo firewall-cmd --reload

# For ufw (Ubuntu/Debian)
sudo ufw status
sudo ufw allow ssh
sudo ufw reload

3 Test Connectivity and Service Configuration

Use telnet or nc from the client to test the basic TCP connection and review the service's configuration file.

BASH

 $ # Test if the port is reachable (replace IP and port)
nc -zv 192.168.1.10 22

# Check the service config file (e.g., SSH)
sudo cat /etc/ssh/sshd_config | grep -E '^ListenAddress|^Port'