Linux Networking Commands

Linux provides many command-line tools for inspecting network interfaces, testing connectivity, viewing routes, checking open ports, and troubleshooting network problems. These commands are essential for Linux administrators and developers.

Why Learn Linux Networking Commands?

Network issues can affect applications, servers, and cloud workloads. Linux networking commands help identify whether a problem is related to the interface, routing, DNS, connectivity, or a listening service.

              
TEXT

            Check Interface → Test Connectivity → Inspect Route → Check DNS → Inspect Ports → Troubleshoot

Using the ip Command

The ip command is one of the primary tools for managing and inspecting network interfaces, addresses, routes, and other networking information.

              
BASH

            ip addr
ip link
ip route

Checking Network Interfaces

The ip addr command displays network interfaces and their assigned IP addresses.

              
BASH

            ip addr show
ip link show

Testing Connectivity with ping

The ping command sends ICMP echo requests to test whether a host is reachable and to measure round-trip response time.

              
BASH

            ping example.com
ping -c 4 8.8.8.8

Checking Network Routes

The routing table determines where network traffic is sent. The ip route command displays the routes configured on the system.

              
BASH

            ip route
ip route get 8.8.8.8

Checking Open Ports with ss

The ss command displays sockets and listening network services. It is commonly used to identify which services are listening on specific ports.

              
BASH

            ss -tuln
ss -tulpn

Testing DNS Resolution

DNS translates domain names into IP addresses. Tools such as dig and nslookup can be used to inspect DNS resolution.

              
BASH

            dig example.com
nslookup example.com

Using curl for Network Testing

curl can be used to test HTTP and HTTPS connections, inspect responses, and verify whether a web service is reachable.

              
BASH

            curl -I https://example.com
curl -v https://example.com

Linux Networking Command Table

Command	Purpose	Example
ip	Inspect interfaces and routes	ip addr
ping	Test connectivity	ping example.com
ss	Inspect sockets and ports	ss -tuln
dig	Query DNS	dig example.com
curl	Test HTTP services	curl -I https://example.com
traceroute	Inspect network path	traceroute example.com

Example Troubleshooting Scenario

              
TEXT

            Website Not Loading → Check Interface → Test IP Connectivity → Check DNS → Inspect Route → Test Port → Check Service

Checking Network Configuration

Check IP addresses with ip addr
Check routes with ip route
Check DNS configuration
Check listening ports with ss
Test remote connectivity with ping or curl

Common Linux Networking Problems

Incorrect IP configuration
Missing default route
DNS resolution failure
Blocked network ports
Service not listening
Firewall configuration issues

Common Mistakes to Avoid

Assuming DNS is the problem without testing IP connectivity
Checking the wrong network interface
Ignoring the routing table
Forgetting to check whether a service is listening
Running network changes without understanding their impact

Advanced Linux Networking Concepts

Network namespaces
Virtual network interfaces
Bridges
Routing tables
iptables and nftables
TCP and UDP sockets
Network troubleshooting with packet capture

Practice Exercises

Display all network interfaces
Find your system's IP address
Test connectivity to a remote host
Display the default route
Find listening TCP and UDP ports
Perform a DNS lookup
Test an HTTP endpoint with curl

Conclusion

Linux networking commands provide powerful tools for understanding and troubleshooting network connectivity. Learning ip, ping, ss, dig, curl, and routing commands gives administrators a strong foundation for diagnosing common network problems.

Note: Note: Run networking commands carefully on production systems, especially commands that modify interfaces, routes, or firewall rules.