Linux Network Connection Timeout

A network connection timeout occurs when a system attempts to establish a connection to another host but doesn't receive a response within the configured timeout period. This differs from 'Connection Refused' where the host actively rejects the connection.

Common Causes

Network connectivity issues between source and destination
Firewall blocking the connection attempt
Destination service not running or not listening on the expected port
DNS resolution failures
Incorrect routing or network configuration

How to Fix

1 Check Basic Connectivity

Verify network connectivity to the destination using ping and traceroute.

BASH

 $ ping -c 4 example.com
traceroute example.com

2 Test Specific Port Connectivity

Use telnet or nc to test if a specific port is reachable.

BASH

 $ telnet example.com 80
# OR
nc -zv example.com 443

3 Check Local Firewall Rules

Inspect iptables or firewalld rules that might be blocking outbound connections.

BASH

 $ sudo iptables -L -n -v
# OR
sudo firewall-cmd --list-all

4 Verify DNS Resolution

Check if the hostname resolves correctly to an IP address.

BASH

 $ nslookup example.com
dig example.com
host example.com

5 Increase Connection Timeout

For applications that support it, increase the connection timeout value.

BASH

 $ # Example for curl
curl --connect-timeout 30 https://example.com