ifconfig (short for ''interface config'') is a system administration utility in

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating systems for network interface configuration. The utility is a

command-line interface A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

tool and is also used in the system

startup script In Unix-based computer operating systems, init (short for ''initialization'') is the first process started during booting of the computer system. Init is a daemon process that continues running until the system is shut down. It is the dire ...

s of many operating systems. It has features for configuring, controlling, and querying

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the su ...

network interface parameters. Ifconfig originally appeared in

4.2BSD The History of the Berkeley Software Distribution begins in the 1970s. 1BSD (PDP-11) The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify an ...

as part of the BSD TCP/IP suite.

Usage

Common uses for ifconfig include setting the

IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...

and

netmask A subnetwork or subnet is a logical subdivision of an IP network. Updated by RFC 6918. The practice of dividing a network into two or more networks is called subnetting. Computers that belong to the same subnet are addressed with an identica ...

of a network interface and disabling or enabling an interface. At boot time, many Unix-like operating systems initialize their network interfaces with

shell script A shell script is a computer program designed to be run by a Unix shell, a command-line interpreter. The various dialects of shell scripts are considered to be scripting languages. Typical operations performed by shell scripts include file man ...

s that call ifconfig. As an interactive tool, system administrators routinely use the utility to display and analyze network interface parameters. The following two examples show the output of the tool when querying the state of a single active interface each on a

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

-based host (interface eth0) and the ural0 interface on an

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installation.

 eth0      Link encap:Ethernet  HWaddr 00:0F:20:CF:8B:42
           inet addr:192.168.1.128  Bcast:  Mask:255.255.255.192
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:2472694671 errors:1 dropped:0 overruns:0 frame:0
           TX packets:44641779 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:1761467179 (1679.7 Mb)  TX bytes:2870928587 (2737.9 Mb)
           Interrupt:28

 ural0: flags=8843 mtu 1500
         lladdr 00:0d:0b:ed:84:fb
         media: IEEE802.11 DS2 mode 11b hostap (autoselect mode 11b hostap)
         status: active
         ieee80211: nwid ARK chan 11 bssid 00:0d:0b:ed:84:fb  100dBm
         inet 172.30.50.1 netmask 0xffffff00 broadcast 172.30.50.255
         inet6 fe80::20d:bff:feed:84fb%ural0 prefixlen 64 scopeid 0xa

* HWaddr: ''hardware address'',

MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking te ...

. * The parameter ''txqueuelen'' is measured in number of

Ethernet frame In computer networking, an Ethernet frame is a data link layer protocol data unit and uses the underlying Ethernet physical layer transport mechanisms. In other words, a data unit on an Ethernet link transports an Ethernet frame as its payload ...

s and is the size of the buffer that is being managed by the

network scheduler A network scheduler, also called packet scheduler, queueing discipline (qdisc) or queueing algorithm, is an arbiter on a node in a packet switching communication network. It manages the sequence of network packets in the transmit and receive q ...

Medium access control functions

ifconfig is also commonly used to change the

medium access control In IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublay ...

(MAC) address of an interface. In this process, the network interface is first disabled (set ''down'') with the ifconfig command, followed by a MAC change command: ifconfig wlan0 down ifconfig wlan0 hw ether 13:11:20:33:49:66 ifconfig wlan0 up

Release status

The

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operating systems (e.g.,

NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is ava ...

, and

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

) continue active development of ifconfig and extension of its functionality to cover the configuration of

wireless networking A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing c ...

interfaces,

VLAN A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2).IEEE 802.1Q-2011, ''1.4 VLAN aims and benefits'' In this context, virtual, refers to a phys ...

trunking, controlling hardware features such as TSO or hardware checksumming or setting up bridge and tunnel interfaces. Solaris has historically used ifconfig for all network interface configuration, but as of Solaris 10 introduced dladm to perform data-link (OSI model layer 2) configuration, reducing ifconfig's purview to IP configuration. In older

Linux distributions A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading one ...

, ifconfig, in conjunction with the utility route, was used to connect a computer to a network, and to define routes between networks. ifconfig for Linux is part of the package ''net-tools'', released as the latest version 2.10 on 7 January 2021. Many Linux distributions have deprecated the use of ifconfig and route in favor of the software suite

iproute2 iproute2 is a collection of userspace utilities for controlling and monitoring various aspects of networking in the Linux kernel, including routing, network interfaces, tunnels, traffic control, and network-related device drivers. iproute2 ...

, such as ArchLinux or RHEL since version 7, which has been available since 1999 for Linux 2.2. iproute2 includes support for all common functions of ifconfig(8), route(8), arp(8) and netstat(1). It also includes multicast configuration support, tunnel and virtual link management, traffic control, and low-level IPsec configuration, among other features.

Related tools

Another higher-level Linux command line tool is ifup (including ifdown and ifquery). In addition to controlling the interfaces, it also provides control of other aspects of the network such as specifying the DNS servers to use. The command is configured using the file ''/etc/network/interfaces'', which contains "stanzas" for each interface. Network Manager is a Linux daemon that automatically reconfigures the network in dynamic environments, such as moving between WiFi hotspots. It is usually used in conjunction with a graphical front-end such as

GNOME Shell GNOME Shell is the graphical shell of the GNOME desktop environment starting with version 3, which was released on April 6, 2011. It provides basic functions like launching applications, switching between windows and is also a widget engine. ...

. Versions of

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

from

Windows 95 Windows 95 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of operating systems. The first operating system in the 9x family, it is the successor to Windows 3.1x, and was released to manufacturi ...

Windows Me Windows Millennium Edition, or Windows Me (marketed with the pronunciation of the pronoun "me"), is an operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It is the successor to Windo ...

used winipcfg to give a graphical display of current IP information. ipconfig, a command similar to ifconfig, comes with

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washi ...

operating-systems based on the

Windows NT Windows NT is a proprietary graphical operating system produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system. The first version of Win ...

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learn ...

. ipconfig also controls the Windows

DHCP The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a cli ...

client Client(s) or The Client may refer to: * Client (business) * Client (computing), hardware or software that accesses a remote service on another computer * Customer or client, a recipient of goods or services in return for monetary or other valuabl ...

. In

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

, the ifconfig command functions as a wrapper to the IPConfiguration agent, and can control the

BootP The Bootstrap Protocol (BOOTP) is a computer networking protocol used in Internet Protocol networks to automatically assign an IP address to network devices from a configuration server. The BOOTP was originally defined in RFC 951. While some part ...

and DHCP clients from the command-line. Use of ifconfig to modify network settings in Mac OS X is discouraged, because ifconfig operates below the level of the system frameworks which help manage network configuration. iwconfig, a component of Wireless tools for Linux, which took its name from ifconfig, manages

wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing ...

interfaces outside the original scope of Linux's ifconfig. iwconfig sets such specialized settings as a wireless network's SSID and WEP keys, and functions in tandem with

iwlist Wireless tools for Linux is a collection of user-space utilities written for Linux kernel-based operating systems to support and facilitate the configuration of device drivers of wireless network interface controllers and some related aspects of ...

. Linux also features

iwspy Wireless tools for Linux is a collection of user-space utilities written for Linux kernel-based operating systems to support and facilitate the configuration of device drivers of wireless network interface controllers and some related aspects of ...

, to read the signal, noise and quality of a wireless connection. Other related tools for configuring Ethernet adapters are: ethtool, mii-tool, and mii-diag in Linux and the command '' dladm show-link'' in Solaris. The ip suite has a similar purpose and is meant to replace the

deprecated In several fields, especially computing, deprecation is the discouragement of use of some terminology, feature, design, or practice, typically because it has been superseded or is no longer considered efficient or safe, without completely removing ...

ifconfig.

References

External links

ifconfig(8)
official

manpage A man page (short for manual page) is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs (including library and system calls), formal standards and conventions, and ...

for Linux net-tools ifconfig
ifconfig(8)
manpage for the