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IFCONFIG(8)		  BSD System Manager's Manual		   IFCONFIG(8)

     ifconfig -- configure network interface parameters

     ifconfig [-L] [-m]	interface [create] [address_family] [address
	      [dest_address]] [parameters]
     ifconfig interface	destroy
     ifconfig -a [-L] [-d] [-m]	[-u] [address_family]
     ifconfig -l [-d] [-u] [address_family]
     ifconfig [-L] [-d]	[-m] [-u] [-C]

     The ifconfig utility is used to assign an address to a network interface
     and/or configure network interface	parameters.  The ifconfig utility must
     be	used at	boot time to define the	network	address	of each	interface
     present on	a machine; it may also be used at a later time to redefine an
     interface's address or other operating parameters.

     The following options are available:

	     For the DARPA-Internet family, the	address	is either a host name
	     present in	the host name data base, hosts(5), or a	DARPA Internet
	     address expressed in the Internet standard	"dot notation".

	     It	is also	possible to use	the CIDR notation (also	known as the
	     slash notation) to	include	the netmask.  That is, one can specify
	     an	address	like

	     For "inet6" family, it is also possible to	specify	the prefix
	     length using the slash notation, like ::1/128.  See the prefixlen
	     parameter below for more information.

	     The link-level ("link") address is	specified as a series of
	     colon-separated hex digits.  This can be used to e.g. set a new
	     MAC address on an ethernet	interface, though the mechanism	used
	     is	not ethernet-specific.	If the interface is already up when
	     this option is used, it will be briefly brought down and then
	     brought back up again in order to ensure that the receive filter
	     in	the underlying ethernet	hardware is properly reprogrammed.

	     Specify the address family	which affects interpretation of	the
	     remaining parameters.  Since an interface can receive transmis-
	     sions in differing	protocols with different naming	schemes, spec-
	     ifying the	address	family is recommended.	The address or proto-
	     col families currently supported are "inet", "inet6", "atalk",
	     "ipx", and	"link".	 The default is	"inet".	 "ether" and "lladdr"
	     are synonyms for "link".

	     Specify the address of the	correspondent on the other end of a
	     point to point link.

	     This parameter is a string	of the form "name unit", for example,

     The following parameters may be set with ifconfig:

     add     Another name for the alias	parameter.  Introduced for compatibil-
	     ity with BSD/OS.

     alias   Establish an additional network address for this interface.  This
	     is	sometimes useful when changing network numbers,	and one	wishes
	     to	accept packets addressed to the	old interface.	If the address
	     is	on the same subnet as the first	network	address	for this in-
	     terface, a	non-conflicting	netmask	must be	given.	Usually
	     0xffffffff	is most	appropriate.

     -alias  Remove the	network	address	specified.  This would be used if you
	     incorrectly specified an alias, or	it was no longer needed.  If
	     you have incorrectly set an NS address having the side effect of
	     specifying	the host portion, removing all NS addresses will allow
	     you to respecify the host portion.

	     (Inet6 only.)  Specify that the address configured	is an anycast
	     address.  Based on	the current specification, only	routers	may
	     configure anycast addresses.  Anycast address will	not be used as
	     source address of any of outgoing IPv6 packets.

     arp     Enable the	use of the Address Resolution Protocol (arp(4))	in
	     mapping between network level addresses and link level addresses
	     (default).	 This is currently implemented for mapping between
	     DARPA Internet addresses and IEEE 802 48-bit MAC addresses	(Eth-
	     ernet, FDDI, and Token Ring addresses).

     -arp    Disable the use of	the Address Resolution Protocol	(arp(4)).

	     (Inet only.)  Specify the address to use to represent broadcasts
	     to	the network.  The default broadcast address is the address
	     with a host part of all 1's.

     debug   Enable driver dependent debugging code; usually, this turns on
	     extra console error logging.

     -debug  Disable driver dependent debugging	code.

	     Put interface into	permanently promiscuous	mode.

	     Disable permanently promiscuous mode.

     delete  Another name for the -alias parameter.

     down    Mark an interface "down".	When an	interface is marked "down",
	     the system	will not attempt to transmit messages through that in-
	     terface.  If possible, the	interface will be reset	to disable re-
	     ception as	well.  This action does	not automatically disable
	     routes using the interface.

     eui64   (Inet6 only.)  Fill interface index (lowermost 64bit of an	IPv6
	     address) automatically.

     media type
	     If	the driver supports the	media selection	system,	set the	media
	     type of the interface to type.  Some interfaces support the mutu-
	     ally exclusive use	of one of several different physical media
	     connectors.  For example, a 10Mb/s	Ethernet interface might sup-
	     port the use of either AUI	or twisted pair	connectors.  Setting
	     the media type to "10base5/AUI" would change the currently	active
	     connector to the AUI port.	 Setting it to "10baseT/UTP" would ac-
	     tivate twisted pair.  Refer to the	interfaces' driver specific
	     documentation or man page for a complete list of the available

     mediaopt opts
	     If	the driver supports the	media selection	system,	set the	speci-
	     fied media	options	on the interface.  The opts argument is	a
	     comma delimited list of options to	apply to the interface.	 Refer
	     to	the interfaces'	driver specific	man page for a complete	list
	     of	available options.

     -mediaopt opts
	     If	the driver supports the	media selection	system,	disable	the
	     specified media options on	the interface.

     tunnel src_addr dest_addr
	     (IP tunnel	devices	only.)	Configure the physical source and des-
	     tination address for IP tunnel interfaces (gif(4)).  The argu-
	     ments src_addr and	dest_addr are interpreted as the outer
	     source/destination	for the	encapsulating IPv4/IPv6	header.

	     Unconfigure the physical source and destination address for IP
	     tunnel interfaces previously configured with tunnel.

     create  Create the	specified network pseudo-device.  If the interface is
	     given without a unit number, try to create	a new device with an
	     arbitrary unit number.  If	creation of an arbitrary device	is
	     successful, the new device	name is	printed	to standard output.

	     Destroy the specified network pseudo-device.

     plumb   Another name for the create parameter.  Included for Solaris com-

	     Another name for the destroy parameter.  Included for Solaris

     vlan vlan_tag
	     If	the interface is a vlan	pseudo interface, set the vlan tag
	     value to vlan_tag.	 This value is a 16-bit	number which is	used
	     to	create an 802.1Q vlan header for packets sent from the vlan
	     interface.	 Note that vlan	and vlandev must both be set at	the
	     same time.

     vlandev iface
	     If	the interface is a vlan	pseudo device, associate physical in-
	     terface iface with	it.  Packets transmitted through the vlan in-
	     terface will be diverted to the specified physical	interface
	     iface with	802.1Q vlan encapsulation.  Packets with 802.1Q	encap-
	     sulation received by the parent interface with the	correct	vlan
	     tag will be diverted to the associated vlan pseudo-interface.
	     The vlan interface	is assigned a copy of the parent interface's
	     flags and the parent's ethernet address.  The vlandev and vlan
	     must both be set at the same time.	 If the	vlan interface already
	     has a physical interface associated with it, this command will
	     fail.  To change the association to another physical interface,
	     the existing association must be cleared first.

	     Note: if the link0	flag is	set on the vlan	interface, the vlan
	     pseudo interface's	behavior changes: the link0 tells the vlan in-
	     terface that the parent interface supports	insertion and extrac-
	     tion of vlan tags on its own (usually in firmware)	and that it
	     should pass packets to and	from the parent	unaltered.

     -vlandev iface
	     If	the driver is a	vlan pseudo device, disassociate the physical
	     interface iface from it.  This breaks the link between the	vlan
	     interface and its parent, clears its vlan tag, flags and its link
	     address and shuts the interface down.

     metric n
	     Set the routing metric of the interface to	n, default 0.  The
	     routing metric is used by the routing protocol (routed(8)).
	     Higher metrics have the effect of making a	route less favorable;
	     metrics are counted as addition hops to the destination network
	     or	host.

     mtu n   Set the maximum transmission unit of the interface	to n, default
	     is	interface specific.  The MTU is	used to	limit the size of
	     packets that are transmitted on an	interface.  Not	all interfaces
	     support setting the MTU, and some interfaces have range restric-

     netmask mask
	     (Inet only.)  Specify how much of the address to reserve for sub-
	     dividing networks into sub-networks.  The mask includes the net-
	     work part of the local address and	the subnet part, which is
	     taken from	the host field of the address.	The mask can be	speci-
	     fied as a single hexadecimal number with a	leading	`0x', with a
	     dot-notation Internet address, or with a pseudo-network name
	     listed in the network table networks(5).  The mask	contains 1's
	     for the bit positions in the 32-bit address which are to be used
	     for the network and subnet	parts, and 0's for the host part.  The
	     mask should contain at least the standard network portion,	and
	     the subnet	field should be	contiguous with	the network portion.

	     The netmask can also be specified in CIDR notation	after the ad-
	     dress.  See the address option above for more information.

     prefixlen len
	     (Inet6 only.)  Specify that len bits are reserved for subdividing
	     networks into sub-networks.  The len must be integer, and for
	     syntactical reason	it must	be between 0 to	128.  It is almost al-
	     ways 64 under the current IPv6 assignment rule.  If the parameter
	     is	omitted, 64 is used.

	     The prefix	can also be specified using the	slash notation after
	     the address.  See the address option above	for more information.

     range netrange
	     Under appletalk, set the interface	to respond to a	netrange of
	     the form startnet-endnet.	Appletalk uses this scheme instead of
	     netmasks though FreeBSD implements	it internally as a set of net-

     remove  Another name for the -alias parameter.  Introduced	for compati-
	     bility with BSD/OS.

     phase   The argument following this specifies the version (phase) of the
	     Appletalk network attached	to the interface.  Values of 1 or 2
	     are permitted.

	     Enable special processing of the link level of the	interface.
	     These three options are interface specific	in actual effect, how-
	     ever, they	are in general used to select special modes of opera-
	     tion.  An example of this is to enable SLIP compression, or to
	     select the	connector type for some	Ethernet cards.	 Refer to the
	     man page for the specific driver for more information.

	     Disable special processing	at the link level with the specified

     up	     Mark an interface "up".  This may be used to enable an interface
	     after an "ifconfig	down".	It happens automatically when setting
	     the first address on an interface.	 If the	interface was reset
	     when previously marked down, the hardware will be re-initialized.

     ssid ssid
	     For IEEE 802.11 wireless interfaces, set the desired Service Set
	     Identifier	(aka network name).  The SSID is a string up to	32
	     characters	in length and may be specified as either a normal
	     string or in hexadecimal when proceeded by	`0x'.  Additionally,
	     the SSID may be cleared by	setting	it to `-'.

     nwid ssid
	     Another name for the ssid parameter.  Included for	NetBSD compat-

     stationname name
	     For IEEE 802.11 wireless interfaces, set the name of this sta-
	     tion.  It appears that the	station	name is	not really part	of the
	     IEEE 802.11 protocol though all interfaces	seem to	support	it.
	     As	such it	only seems to be meaningful to identical or virtually
	     identical equipment.  Setting the station name is identical in
	     syntax to setting the SSID.

     station name
	     Another name for the stationname parameter.  Included for BSD/OS

     channel number
	     For IEEE 802.11 wireless interfaces, set the desired channel.
	     Channels range from 1 to 14, but the exact	selection available
	     depends on	the region your	adaptor	was manufactured for.  Setting
	     the channel to 0 will give	you the	default	for your adaptor.
	     Many adaptors ignore this setting unless you are in ad-hoc	mode.

     authmode mode
	     For IEEE 802.11 wireless interfaces, set the desired authentica-
	     tion mode in infrastructure mode.	Not all	adaptors support all
	     modes.  The set of	valid modes is "none", "open", and "shared".
	     Modes are case insensitive.

	     For IEEE 802.11 wireless interfaces, enable powersave mode.

	     For IEEE 802.11 wireless interfaces, disable powersave mode.

     powersavesleep sleep
	     For IEEE 802.11 wireless interfaces, set the desired max power-
	     save sleep	time in	milliseconds.

     wepmode mode
	     For IEEE 802.11 wireless interfaces, set the desired WEP mode.
	     Not all adaptors support all modes.  The set of valid modes is
	     "off", "on", and "mixed".	"Mixed"	mode explicitly	tells the
	     adaptor to	allow association with access points which allow both
	     encrypted and unencrypted traffic.	 On these adaptors, "on" means
	     that the access point must	only allow encrypted connections.  On
	     other adaptors, "on" is generally another name for	"mixed".
	     Modes are case insensitive.

     weptxkey index
	     For IEEE 802.11 wireless interfaces, set the WEP key to be	used
	     for transmission.

     wepkey key|index:key
	     For IEEE 802.11 wireless interfaces, set the selected WEP key.
	     If	an index is not	given, key 1 is	set.  A	WEP key	will be	either
	     5 or 13 characters	(40 or 104 bits) depending of the local	net-
	     work and the capabilities of the adaptor.	It may be specified
	     either as a plain string or as a string of	hexadecimal digits
	     proceeded by `0x'.	 For maximum portability, hex keys are recom-
	     mended; the mapping of text keys to WEP encryption	is usually
	     driver-specific.  In particular, the Windows drivers do this map-
	     ping differently to FreeBSD.  A key may be	cleared	by setting it
	     to	`-'.  If WEP is	supported then there are at least four keys.
	     Some adaptors support more	than four keys.	 If that is the	case,
	     then the first four keys (1-4) will be the	standard temporary
	     keys and any others will be adaptor specific keys such as perma-
	     nent keys stored in NVRAM.

     wep     Another way of saying wepmode on.	Included for BSD/OS compati-

     -wep    Another way of saying wepmode off.	 Included for BSD/OS compati-

     nwkey key
	     Another way of saying:

	     "wepmode on weptxkey 1 wepkey 1:key wepkey	2:- wepkey 3:- wepkey

	     Included for NetBSD compatibility.

     nwkey n:k1,k2,k3,k4
	     Another way of saying

	     "wepmode on weptxkey n wepkey 1:k1	wepkey 2:k2 wepkey 3:k3	wepkey

	     Included for NetBSD compatibility.

     -nwkey  Another way of saying wepmode off.

	     Included for NetBSD compatibility.

     The ifconfig utility displays the current configuration for a network in-
     terface when no optional parameters are supplied.	If a protocol family
     is	specified, ifconfig will report	only the details specific to that pro-
     tocol family.

     If	the driver does	supports the media selection system, the supported me-
     dia list will be included in the output.

     If	the -m flag is passed before an	interface name,	ifconfig will display
     all of the	supported media	for the	specified interface.  If -L flag is
     supplied, address lifetime	is displayed for IPv6 addresses, as time off-
     set string.

     Optionally, the -a	flag may be used instead of an interface name.	This
     flag instructs ifconfig to	display	information about all interfaces in
     the system.  The -d flag limits this to interfaces	that are down, and -u
     limits this to interfaces that are	up.  When no arguments are given, -a
     is	implied.

     The -l flag may be	used to	list all available interfaces on the system,
     with no other additional information.  Use	of this	flag is	mutually ex-
     clusive with all other flags and commands,	except for -d (only list in-
     terfaces that are down) and -u (only list interfaces that are up).

     The -C flag may be	used to	list all of the	interface cloners available on
     the system, with no additional information.  Use of this flag is mutually
     exclusive with all	other flags and	commands.

     Only the super-user may modify the	configuration of a network interface.

     The media selection system	is relatively new and only some	drivers	sup-
     port it (or have need for it).

     Messages indicating the specified interface does not exist, the requested
     address is	unknown, or the	user is	not privileged and tried to alter an
     interface's configuration.

     IPv6 link-local addresses are required for	several	basic communication
     between IPv6 node.	 If they are deleted by	ifconfig manually, the kernel
     might show	very strange behavior.	So, such manual	deletions are strongly

     netstat(1), netintro(4), rc(8), routed(8)

     The ifconfig utility appeared in 4.2BSD.

BSD				 July 2, 2001				   BSD


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