ifconfig

What is ifconfig?

Ifconfig (interface configuration) is a command-line utility used to retrieve, display, and configure network interfaces on machines running Unix-like operating systems, including Linux, macOS, and BSD. On Windows, the command for displaying and configuring network-related information is ‘ipconfig’.  

Ifconfig is used to retrieve and display information about the system’s network interfaces, providing a way to configure details like IP addresses, network masks, broadcast addresses, and other parameters.

Ifconfig is a deprecated command. Deprecated commands are often removed from an operating system because they are outdated or pose a security risk. Ifconfig has been replaced with newer by the ip command, part of the Linux iproute2 collection of utilities for controlling TCP / IP networking and traffic control in Linux.

Despite its depreciation, ifconfig can still be installed on some Linux distributions, as shown in this LinuxConfig tutorial. However, it is highly recommended that newer utilities be used.

Techopedia Explains the ifconfig Meaning

Ifconfig is used to display and configure network interfaces on systems running Linux and related operating systems. It allows users to configure a variety of network parameters, like IP addresses and network masks. Ifconfig has been replaced with a newer tool called ‘ip’, which offers more advanced features and better control.

How Does ifconfig Work?

When the command is run without any arguments (‘ifconfig’), it will display information about all active network interfaces. 

Detailed information about a specific interface can be displayed by providing the interface name as an argument. For example, ‘ifconfig eth1‘ will display detailed information about the “eth1″ network interface, providing information like IP address, MAC address, and other network configuration settings.

The ifconfig command is also used to configure network interfaces. For example, the following command would be used to deactivate the “eth1” interface: ‘sudo ifconfig eth1 down’.

When modifying network configurations, use ‘sudo’, as these changes require administrator privileges.

Starting ifconfig

• Open a terminal or command prompt
• Type ‘ifconfig’ and press Enter

Since ifconfig is a command-line tool, users will need to open a terminal or command prompt on the system. On Linux, you can find a terminal in your applications menu or use a keyboard shortcut like Ctrl + Alt + T.  

Once the terminal or command prompt is open, type ‘ifconfig’ and press Enter to display information about all active network interfaces on the system.

Configuring Networks with ifconfig

One common use of ifconfig is to retrieve and display detailed information about the system network interfaces. This includes:

• IP addresses
• MAC (Media Access Control) addresses
• Network masks
• Statistics about data transmission

The tool also provides a way to configure aspects of the network, such as enabling or disabling network connectivity, changing the MAC address of a network interface, or capturing and analyzing network traffic.

ifconfig Commands

In the following examples, ifconfig commands “eth1” would be replaced with the actual name of your network interface.

This IBM guide offers additional examples of ifconfig syntax, flags, and parameters

ipconfig vs. ifconfig

Uses of ifconfig

Common uses of ifconfig include the following:

• Activate/Deactivate Interfaces
• Adjust MTU (Maximum Transmission Unit)
• Change MAC Addresses
• Check Interface Statistics
• Configure VLAN (Virtual LAN) Interfaces
• Display Interface Information
• Enable/Disable Broadcast Mode
• Enable/Disable Multicast Mode

Examples Using ifconfig Command

Examples using “eth1” as the network interface name:

The Bottom Line

Ifconfig serves as a flexible command-line tool for managing network interfaces on Linux. It is used to retrieve and display detailed information about the system’s network interfaces and offers a good amount of network configuration options for users.

It’s important to remember that ifconfig is deprecated (March 2009) and has been largely replaced by the ip command – part of the Linux iproute2 collection of networking utilities.

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