Linux Basic Networking for Beginners - Complete Guide 2025

 

Introduction

One of the most fundamental topics is to understand networking basics. It is a very crucial aspect to understand the way networking works in Linux, whether you are configuring servers, troubleshooting a network that is not connecting, or even just setting up a local network.  This guide will help beginners and system administrators to understand how to configure, manage and troubleshoot networking issues in Linux systems and covers some basic settings, such as how to assign IP address, gateway, DNS, configure a hostname and how to add or delete routes.

In this Linux Basic Networking for Beginners - 2025 Complete Guide, you have a step-by-step guide on how to view network configurations, manage network configurations and troubleshoot the network configurations using simple but powerful Linux commands. We will go through all the operations of checking the current network settings to assigning IPs, routes, and troubleshooting connectivity.

At the end of this guide as a system administrator, you will be in a better position to implement networking basics and troubleshooting.

1. What Networking Means in Linux

Networking is the process of connecting systems to other computers or devices so they can exchange data. This connection can be local within the same network or globally connected through the internet. Linux has powerful built-in tools that allow users to configure, manage and monitor these network connections efficiently.

Networking in Linux is to understand how your system communicates using the network interface, IP address and routing table.  Every piece plays an important role in sending and receiving data packets across networks.

Network interfaces

A network interface serves as a point of connection between a device or computer and a network. Linux includes physical interfaces such as eth0 or wlan0, and virtual interfaces such as loopback (lo) and br0 (bridge). You can view the available interfaces using:

1. Using ifconfig

#ifconfig

2. Using the ip command

#ip a

IP Addresses

An IP address is fundamental for network connectivity, and every device connected to a network needs a unique one. It is used to identify and route data to the correct system on the network. Linux supports both IPv4 and IPv6 addressing. You can view your system’s IP address details using the ifconfig, ip a, or ip addr show command.

#ip addr show

Routing

In Linux, routing is a process of determining the path that a network packet takes to reach its destination. The Linux kernel maintains a routing table to decide where to send outgoing packets. You can display the routing table details using the following command.

#route

Or

#route -n

Linux Network Configuration Files and Tools

Linux network settings can be managed both by command-line utilities and configuration files. Common files and tools are:

Tool/File	Purpose
/etc/network/interfaces	Stores static network configurations (Debian/Ubuntu old version)
/etc/netplan	Stores static network configurations (Debian/Ubuntu new version)
/etc/sysconfig/network-scripts/ifcfg-*	Network interface configs (RHEL/CentOS)
/etc/resolv.conf	DNS configuration
/etc/hostname	System hostname
ip / ifconfig	Manage interfaces and IPs
Nmcli / nmtui	Network Manager command-line and text UI tools
Ping, traceroute, netstat	Troubleshooting and monitoring tools

3. Key Networking Concepts in Linux

Before configuring and troubleshooting a Linux network, one should be familiar with the fundamental concepts that form the basis of system communication with one another. These are IP address, subnet mask, gateway, DNS, and hostname, which are common terminologies used in the network setup and also key to any Linux user.

IP Address (IPv4 / IPv6)

An IP address (Internet Protocol) is a unique identifier assigned to every device on the network. It tells the systems where to send data.

• IPv4 uses a 32-bit format (e.g., 192.168.1.8)
• IPv6 uses a 128-bit format (e.g., fe08::2ff::fe23::4567::890b)

You can check your IP address in Linux using commands like ifconifg or ip addr show.

Subnet Mask

A subnet mask differentiates between the host portion and network portion in an IP address.  It helps Linux to understand which systems are on the local network and which systems need routing through the gateway.

Common examples include:

• 255.255.255.0 (For small local networks)
• CIDR notation: /24 (equivalent to 255.255.255.0)

For example:

Your IP is 192.168.1.7 and subnet mask 255.255.255.0, it means your device can directly communicate with any system in the range 192.168.1.1 – 192.168.1.254.

Gateway

A gateway is a device or router that connects your local network to other networks or the internet. It acts as an exit door for packets that need to travel outside your network.

You can view your current gateway using ip route show or route -n command.

DNS (Domain Name System)

DNS translates human-readable domains into IP addresses that computers understand, like seeklinux.net to IP address. DNS configuration is stored in /etc/resolv.conf in Linux.                                             

When you ping google.com DNS first resolves it to an IP address (e.g., 142.250.183.110).

Hostname

A hostname is the name you assigned to your Linux system to uniquely identify it on the network. It's like a label that makes your device recognizable, rather than its IP address.

To view the hostname

Sudo hostnamectl set-hostname your hostname to set or change hostname

4. Viewing Network Information in Linux

Before making any changes to network configuration, it is important to understand the current network setup. Linux provides several commands that allow you to view interface details, assigned IP addresses and routing information. These tools help you to verify connectivity, troubleshoot issues and confirm changes in configurations.

1. Check Current Network Configuration using ip addr show

The ip command is more reliable for viewing and managing network details in Linux.

To display all available network interfaces and their assigned IP address, run:

#ip addr show

Explanation:

• Ens33 – interface name
• Inet 192.168.1.7/24 – Ipv4 address with subnet
• State UP – Interface is active and running

2. Check Network Configuration Using ipconfig (Legacy Command)

The ifconfig command was traditionally used to view the network interface configuration. It is now replaced by ip. It’s still available on many systems for compatibility.

#ifconfig

If ifconfig is not installed by default, you can install it by:

#sudo apt install net-tools

3. Display Interface Names using ip link show

To show all network interfaces both active and inactive use:

#ip link show

• Lo – loopback interface used for internal communication
• Ens33 or eth0 – Physical or virtual network interface connected to the network

Interface names may vary by distribution, for example

• Older systems – eth1, eth0
• New systems – ens33, enp0s3

4. Check the Default Gateway Using ip route show

To see your routing table and find the default gateway (the device that connects your system to external networks), use:

#ip route show

• Gateway IP Address – 192.168.1.1
• Ens33 – Interface used to reach that gateway

Note: Always verify your network information before and after making configuration changes. This helps ensure that your system is connected using the expected interfaces, IPs and routes.

5. Assigning an IP Address in Linux

You can assign an IP address to a network interface temporarily using commands or permanently by editing configuration files in Linux. Knowing both methods is important: a temporary assignment is useful for quick testing, while permanent configurations ensure network settings persist after reboot.

1. Temporary IP Assignment (Using Commands)

To assign a new IP address to a specific interface, like eth0 or ens33, use the ip command:

#sudo ip addr add 192.168.1.10/24 dev ens33

• 192.168.1.10 – IP address you want to assign
• /24 – subnet mask (equivalent to 255.255.255.0)
• Dev ens33 – Network interface name

After running this command, you can verify the assigned IP using:

#ip addr show ens33

This method does not persist after a reboot; it is best for temporary testing.

2. Removing an Assigned IP Address

If you want to remove a temporarily assigned IP address, use the following command:

#sudo ip addr del 192.168.1.10/24 dev ens33

3. Permanent Assignment (via Configuration File)

To make your IP configuration permanent edit the network configuration file. The location and syntax may slightly vary depending on your Linux distribution.

For Ubuntu use (/etc/netplan/filename.yaml)

Open the configuration file with a text editor

#sudo nano /etc/netplan/50-cloud-init.yaml

• ens33 – Automatically enable the interface at boot
• Addresses – Assigned IP address
• Name server – DNS IP address
• Gateway – 192.168.1.1

After saving the file, restart the networking services for the changes to take effect.

#sudo service NetworkManager restart

If your system uses NetworkManager, you can use nmcli or nmtui tools to set static IPs more easily.

6. Setting the Default Gateway in Linux

A default gateway is the device, usually a router that allows your Linux system to communicate with other devices outside its local network, including the internet. When your system needs to send data to an address that is not in the same subnet, it forwards the traffic to the default gateway.

1. View Current routes

To view the existing routing table and find your current default gateway run:

#ip route show

• Default via 192.168.1.1 – your current default gateway
• 192.168.1.0/24 – your local network range

2. Add a New Default Gateway

If you want to manually set or change the gateway, use the following command:

#sudo ip route add default via 192.168.1.1

• Default – Specifies a route for all traffic not otherwise matched
• Via 192.168.1.1 – IP address of your router or Gateway

After adding the route, verify that it’s active:

#ip route show

3. Delete an Existing Default Route

To remove the current default gateway, use this command.

#sudo ip route del default

You can confirm it's removed with the command:

#ip route

This is useful when switching to a new gateway or troubleshooting routing issues.

4. Verifying the Configuration

After adding your gateway, verify network connectivity by pinging an external host.

#ping

If the ping is successful, it means your gateway and routing are configured correctly.

5. Make Gateway Persistent

If you want the gateway settings to remain after reboot, add it to your network configuration file.

For Ubuntu

Then restart the networking service.

7. Configuring DNS in Linux

The Domain Name System (DNS) translates human-friendly names like seeklinux.net into IP addresses that computers use to communicate. A perfect configuration of DNS ensures your Linux system can resolve domain names and access website or network resources smoothly.

1. Edit the /etc/resolv.conf File

The simplest way to configure DNS servers in Linux is by editing the /etc/resolv.conf file.

Open the file with a text editor:

#sudo nano /etc/resolv.conf

Each nameserver line specifies a DNS server your system will use to resolve domain names. 8.8.8.8 is Google’s public DNS and 1.1.1.1 is Cloudflare’s DNS.

2. Verify DNS Configuration

You can test whether DNS resolution is working or not with these commands

#ping google.com

Or use DNS lookup tools:

#dig google.com

If you get valid IP address responses, your DNS configuration is working correctly. Always test DNS resolution after modifying configurations. A misconfigured DNS can prevent your system from accessing websites and repositories.

8. Setting the Hostname in Linux

The hostname is the unique name that identifies your Linux system on the network. It helps other devices and users to recognize your machine, making it easier to manage and communicate between systems.

You can view, temporarily change or permanently set the hostname using simple Linux commands or configuration files.

1. Check the Current Hostname

To display your system’s current hostname, use this command:

#hostname

2. Temporarily Change Hostname

If you want to change the hostname temporarily, use this command, it will revert back after reboot.

#sudo hostname new-hostname

3. Permanently Change the Hostname

To make the hostname persistent, you need to edit the config file (/etc/hosts).

#sudo nano /etc/hosts

4. Apply Changes Using hostnamectl

The hostnamectl command is used to manage hostnames (works on most new Linux systems).

#sudo hostnamectl set-hostname seeklinux

You can confirm the change using this command:

#hostnamectl status

After changing the hostname, it’s good to reboot the system or restart the network service to ensure all applications recognize the new hostname.

9. Managing Network Routes in Linux

Routing determines how data packets travel from your Linux system to other networks. The routing table contains all the routes your system uses to decide where to send network traffic. Managing routes manually is useful for configuring advanced networking setups or troubleshooting network issues.

1. View All Routes

To display the current routing table, use this command:

#ip route show

2. Add a Specific Route

To manually add a route to a specific network use:

#sudo route add 192.168.2.1/24 via 192.168.2.1 dev ens33

3. Delete a Route

To remove a specific route command is

#sudo ip route del 192.168.2.0/24

You can confirm removal by checking the routing table using the ip route command. Routes added using ip route add are temporary, they disappear after a reboot. To make them permanent, you can add the route in the network configuration file.

10. Testing and Troubleshooting Network Issues in Linux

After configuration of network settings, it’s important to troubleshoot and test to make sure everything is working as expected. Linux provides several tools to check connectivity, DNS resolution, open ports and network service logs.

1. Check Network Connectivity

The simplest and easiest way to test if your system is reaching to other devices or websites by using the ping command.

#ping 8.8.8.8

2. Test DNS Resolution

To verify DNS configuration and ensure name resolution is working correctly, use the nslookup and dig commands. These commands query DNS servers and return IP address associated with the domain. If no address is returned, then check your /etc/resolv.conf or DNS settings.

3. Check Open Ports and Active Connections

To check the open network ports and services, use netstat or ss:

#netstat –ltun

Or

#ss –ltun

• -t - TCP connections
• -u - UPD connections
• -l - Listening sockets
• -n - Show numeric addresses

4. Restart Networking Service

If your network changes don’t take effect or connectivity drops, try restarting the network service.

#sudo service NetworkManager restart

5. View Network Logs

Logs help you diagnose persistent network problems. View detailed logs for the network manager using:

#journalctl –u NetworkManager

If you are troubleshooting a connection issue:

• Check IP configuration (ip addr show)
• Verify Gateway (ip route show)
• Test DNS (dig, nslookup)
• Restart the network service and check the logs

Quick Reference Table

Command	Description
ip addr	Show or assign IP addresses
ip route	Display or modify routing table
hostnamectl	Manage system hostname
ping	Test connectivity
dig	Check DNS resolution
ss	View network sockets
netstat	Display active connections
ifconfig	Legacy network interface tool

11. FAQ: Linux Basic Networking for Beginners

1. How do I assign a static IP in Linux?

Temporary:

#sudo ip addr add 192.168.1.10/24 dev ens33

This sets the IP until reboot.

Permanent:

Edit your network configuration file (/etc/netplan) to assign an IP address permanently, then restart the networking service with the command:

#sudo service NetworkManager restart

2. How can I permanently set DNS in Linux?

To permanently configure DNS servers, you can modify your system config file (/etc/resolv.conf) and insert your DNS IP address then restart the network service to take effect.

3. What is the command to view my gateway?

To view your default gateway and routing table use ip route show command.

4. How do I change the hostname in Linux?

You can change your hostname temporarily or permanently.

Temporary:

#sudo hostname new-hostname

Permanently:

#sudo hostnamectl set-hostname new-hostname

Then verify with:

#hostnamectl status

Conclusion

Basic networking knowledge in Linux is a skill one must have in server administration, troubleshooting connectivity, or mastering system management. These base commands and files allow you to adjust your system network settings to communicate over a network, whether it is by assigning IP addresses and configuring DNS, or by assigning hostnames and routes.

You will quickly gain confidence in configuring and managing Linux networks effectively by practicing tools such as ip, ping, traceroute and hostnamectl. Whether you are a beginner or an experienced system admin, these networking basics form the backbone of advanced concepts like firewall, DHCP and network security.

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