ifconfig and ip addr in Linux CLI - Commands & Configuration

Introduction

Sometimes you need to see the details of your computer's network connections. The commands ifconfig and ip addr help you check your network interfaces and their settings like IP addresses. This helps you understand or fix network problems.

When you want to see the IP address assigned to your computer.

When you need to check if a network interface is active or down.

When you want to find the MAC address of your network card.

When troubleshooting network connection issues.

When configuring or verifying network settings on a Linux machine.

Commands

This command shows all active network interfaces and their details like IP address and MAC address.

Terminal

ifconfig

Expected Output

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

        inet 192.168.1.10  netmask 255.255.255.0  broadcast 192.168.1.255

        inet6 fe80::a00:27ff:fe4e:66a1  prefixlen 64  scopeid 0x20<link>

        ether 08:00:27:4e:66:a1  txqueuelen 1000  (Ethernet)

        RX packets 1000  bytes 1234567 (1.2 MB)

        TX packets 800  bytes 987654 (987.6 KB)

        Interrupt:19 Base address:0x2000

This command shows all network interfaces with detailed information including IP addresses and interface status.

Terminal

ip addr

Expected Output

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

       valid_lft forever preferred_lft forever

    inet6 ::1/128 scope host

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000

    link/ether 08:00:27:4e:66:a1 brd ff:ff:ff:ff:ff:ff

    inet 192.168.1.10/24 brd 192.168.1.255 scope global dynamic eth0

       valid_lft 86394sec preferred_lft 86394sec

    inet6 fe80::a00:27ff:fe4e:66a1/64 scope link

       valid_lft forever preferred_lft forever

Key Concept

If you remember nothing else, remember: 'ip addr' is the modern, more detailed command to check network interfaces, while 'ifconfig' is older but still commonly used.

Common Mistakes

Trying to use ifconfig on a system where it is not installed by default.

Many modern Linux systems do not include ifconfig by default, so the command will fail.

Use 'ip addr' instead, which is installed by default on modern Linux systems.

Running 'ifconfig' without root privileges and expecting to see all interfaces.

Some interfaces or details may not show without proper permissions.

Run 'sudo ifconfig' or 'sudo ip addr' to see all details.

Summary

Use 'ifconfig' to quickly see active network interfaces and their IP addresses on older systems.

Use 'ip addr' for a detailed and modern view of all network interfaces and their settings.

Both commands help you check network status and troubleshoot connection issues.