ifconfig

From Wikipedia, the free encyclopedia

Jump to: navigation, search

ifconfig (short for interface configurator) is a system administration utility in Unix-like operating systems to configure, control, and query TCP/IP network interface parameters from a command line interface (CLI) or in system configuration scripts. ifconfig originally appeared in 4.2BSD as part of the BSD TCP/IP suite.

Contents

[edit] Usage

Common uses for ifconfig include setting an interface's IP address and netmask, and disabling or enabling a given interface.[1] At boot time, many UNIX-like operating systems initialize their network interfaces with shell-scripts that call ifconfig. As an interactive tool, system administrators routinely use the utility to display and analyze network interface parameters. The following example output samples display the state of a single active interface each on a Linux-based host (interface eth0) and the ural0 interface on an OpenBSD installation.

eth0      Link encap:Ethernet  HWaddr 00:0F:20:CF:8B:42
          inet addr:217.149.127.10  Bcast:217.149.127.63  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 (1679.8 Mb)  TX bytes:2870928587 (2737.9 Mb)
          Interrupt:28



ural0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> 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

[edit] Current status

The free Berkeley Software Distribution UNIX operating systems (e.g., NetBSD, OpenBSD, and FreeBSD) continue active development of ifconfig and extension of its functionality to cover the configuration of wireless networking interfaces, VLAN trunking, controlling hardware features such 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 Linux distributions based on 2.2.x Linux kernels, ifconfig, ipchains, and the route command operated together to connect a computer to a network, to define routes between networks, and to configure firewalls. Distributions based on later kernels have deprecated ifconfig, route, and ipchains, replacing them with iptables and iproute2. iproute2 includes support for all functions of ifconfig(8) and route(8), as well as traffic-control (such as bandwidth shaping). ifconfig for Linux is part of the net-tools package.

[edit] Related tools

Versions of Microsoft Windows from Windows 95 to Windows Me used winipcfg to give a graphical display of current IP information. ipconfig, a command similar to ifconfig, comes with Microsoft operating-systems based on the Windows NT kernel. ipconfig also controls the Windows DHCP client.

In Mac OS X, the ifconfig command functions as a wrapper to the IPConfiguration agent, and can control the BootP 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. To change network settings in Mac OS X from the command line, use /usr/sbin/ipconfig or /usr/sbin/networksetup.

iwconfig (one of the Wireless tools for Linux), which took its name from ifconfig, manages wireless network 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. Linux also features iwspy, 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 for Linux and show-link for Solaris.

[edit] References

  1. ^ Linux Network Administrators Guide Section 5.7. Interface Configuration for IP

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Ifconfig"