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ifconfig(8)

NAME

     ifconfig -- configure network interface parameters

SYNOPSIS

     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]

DESCRIPTION

     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:

     address
	     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 192.168.0.1/16.

	     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.

     address_family
	     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''.

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

     interface
	     This parameter is a string of the form ``name unit'', for exam-
	     ple, ``ed0''.
	     to accept packets addressed to the old interface.	If the address
	     is on the same subnet as the first network address for this
	     interface, 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.

     anycast
	     (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)).

     staticarp
	     If the Address Resolution Protocol is enabled, the host will only
	     reply to requests for its addresses, and will never send any
	     requests.

     -staticarp
	     If the Address Resolution Protocol is enabled, the host will per-
	     form normally, sending out requests and listening for replies.

     broadcast
	     (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.

     promisc
	     Put interface into permanently promiscuous mode.

     -promisc
	     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 interface.  If possible, the interface will be reset
	     to disable reception as well.  This action does not automatically
	     disable routes using the interface.


     maclabel label
	     If Mandatory Access Control support is enabled in the kernel, set
	     the MAC label to label.

     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 activate twisted pair.  Refer to the interfaces' driver
	     specific documentation or man page for a complete list of the
	     available types.

     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.

     mode mode
	     If the driver supports the media selection system, set the speci-
	     fied operating mode on the interface to mode.  For IEEE 802.11
	     wireless interfaces that support multiple operating modes this
	     directive is used to select between 802.11a (``11a''), 802.11b
	     (``11b''), and 802.11g (``11g'') operating modes.

     name name
	     Set the interface name to name.

     rxcsum, txcsum
	     If the driver supports user-configurable checksum offloading,
	     enable receive (or transmit) checksum offloading on the inter-
	     face.  Some drivers may not be able to enable these flags inde-
	     pendently of each other, so setting one may also set the other.
	     The driver will offload as much checksum work as it can reliably
	     support, the exact level of offloading varies between drivers.

     -rxcsum, -txcsum
	     If the driver supports user-configurable checksum offloading,
	     disable receive (or transmit) checksum offloading on the inter-
	     face.  These settings may not always be independent of each
	     other.

     polling
	     If the driver has user-configurable polling(4) support, select
	     the polling mode on the interface.

     -polling
	     If the driver has user-configurable polling(4) support, select

     deletetunnel
	     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
	     unless the interface is renamed or destroyed in the same ifconfig
	     invocation.

     destroy
	     Destroy the specified network pseudo-device.

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

     unplumb
	     Another name for the destroy parameter.  Included for Solaris
	     compatibility.

     vlan vlan_tag
	     If the interface is a vlan(4) 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(4)
	     interface.  Note that vlan and vlandev must both be set at the
	     same time.

     vlandev iface
	     If the interface is a vlan(4) pseudo device, associate physical
	     interface iface with it.  Packets transmitted through the vlan(4)
	     interface 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(4) pseudo-interface.
	     The vlan(4) interface is assigned a copy of the parent inter-
	     face's flags and the parent's ethernet address.  The vlandev and
	     vlan must both be set at the same time.  If the vlan(4) interface
	     already has a physical interface associated with it, this command
	     will fail.  To change the association to another physical inter-
	     face, the existing association must be cleared first.

	     Note: if the hardware tagging capability is set on the parent
	     interface, the vlan(4) pseudo interface's behavior changes: the
	     vlan(4) interface recognizes that the parent interface supports
	     insertion and extraction 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(4) pseudo device, disassociate the physi-
	     cal interface iface from it.  This breaks the link between the
	     vlan(4) interface and its parent, clears its VLAN tag, flags and
	     its link address and shuts the interface down.

     vlanmtu, vlanhwtag
	     If the driver offers user-configurable VLAN support, enable
	     reception of extended frames or tag processing in hardware,

     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-
	     tions.

     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
	     address.  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
	     always 64 under the current IPv6 assignment rule.	If the parame-
	     ter 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-
	     masks.

     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.

     link[0-2]
	     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
	     and received packets are discarded after bpf(4) processing.

     -monitor
	     Take the interface out of monitor mode.

     up      Mark an interface ``up''.	This may be used to enable an inter-
	     face 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-ini-
	     tialized.

     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-
	     ibility.

     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
	     compatibility.

     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.

     powersave
	     For IEEE 802.11 wireless interfaces, enable powersave mode.

     -powersave
	     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.

     protmode technique
	     transmitted frames are preceded by transmission of an RTS control
	     frame.  The length argument is the frame size in bytes and must
	     be in the range 1 to 2312.  Not all adaptors support setting the
	     RTS threshold.

     txpower power
	     For IEEE 802.11 wireless interfaces, set the power used to trans-
	     mit frames.  The power argument is a unitless value in the range
	     0 to 100 that is interpreted by drivers to derive a device-spe-
	     cific value.  Out of range values are truncated.  Typically only
	     a few discreet power settings are available and the driver will
	     use the setting closest to the specified value.  Not all adaptors
	     support changing the transmit power.

     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''.  The ``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 con-
	     nections.	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-
	     bility.

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

     nwkey key
	     Another way of saying:

	     ``wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey
	     4:-''.

	     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
     interface 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
     media list will be included in the output.

     If the -m flag is passed before an interface name, ifconfig will display
     the capability list and all of the supported media for the specified
     interface.  If -L flag is supplied, address lifetime is displayed for
     IPv6 addresses, as time offset 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
     exclusive with all other flags and commands, except for -d (only list
     interfaces 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.

NOTES

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

DIAGNOSTICS

     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.

BUGS

     Basic IPv6 node operation requires a link-local address on each interface
     configured for IPv6.  Normally, such an address is automatically config-
     ured by the kernel on each interface added to the system; this behaviour
     may be disabled by setting the sysctl MIB variable
     net.inet6.ip6.auto_linklocal to 0.

     If you delete such an address using ifconfig, the kernel may act very
     oddly.  Do this at your own risk.

SEE ALSO

     netstat(1), carp(4), netintro(4), polling(4), vlan(4), rc(8), routed(8),
     sysctl(8)

HISTORY

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