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

NAME
     ifconfig -- configure network interface parameters

SYNOPSIS
     ifconfig [-N] interface address_family [address [dest_address]]
              [parameters]
     ifconfig [-hLmNvz] interface [protocol_family]
     ifconfig -a [-bdhLNmsuvz] [protocol_family]
     ifconfig -l [-bdsu]
     ifconfig -s interface
     ifconfig -C

DESCRIPTION
     ifconfig is used to assign an address to a network interface and/or
     configure network interface parameters.  ifconfig 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.

     Available operands for ifconfig:

     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''.  For
             the Xerox Network Systems(tm) family, addresses are
             net:a.b.c.d.e.f, where net is the assigned network number (in
             decimal), and each of the six bytes of the host number, a through
             f, are specified in hexadecimal.  The host number may be omitted
             on Ethernet interfaces, which use the hardware physical address,
             and on interfaces other than the first.  For the ISO family,
             addresses are specified as a long hexadecimal string, as in the
             Xerox family.  However, two consecutive dots imply a zero byte,
             and the dots are optional, if the user wishes to (carefully)
             count out long strings of digits in network byte order.

     address_family
             Specifies the address_family which affects interpretation of the
             remaining parameters.  Since an interface can receive
             transmissions in differing protocols with different naming
             schemes, specifying the address family is recommended.  The
             address or protocol families currently supported are ``inet'',
             ``inet6'', ``atalk'', ``iso'', and ``link''.

     interface
             The interface parameter is a string of the form ``name unit'',
             for example, ``en0''

     The following parameters may be set with ifconfig:

     active          This keyword applies when ifconfig adds or modifies any
                     link-layer address.  It indicates that ifconfig should
                     ``activate'' the address.  Activation makes an address
                     the default source for transmissions on the interface.
                     You may not delete the active address from an interface.
                     You must activate some other address, first.

     advbase n       If the driver is a carp(4) pseudo-device, set the base
                     advertisement interval to n seconds.  This ia an 8-bit
                     number; the default value is 1 second.

     advskew n       If the driver is a carp(4) pseudo-device, skew the
                     advertisement interval by n.  This is an 8-bit number;
                     the default value is 0.

                     Taken together the advbase indicate how frequently, in
                     seconds, the host will advertise the fact that it
                     considers itself the master of the virtual host.  The
                     formula is advbase + (advskew / 256).  If the master does
                     not advertise within three times this interval, this host
                     will begin advertising as master.

     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.

     -alias          Remove the specified network address alias.

     arp             Enable the use of the Address Resolution Protocol in
                     mapping between network level addresses and link level
                     addresses (default).  This is currently implemented for
                     mapping between DARPA Internet addresses and Ethernet
                     addresses.

     -arp            Disable the use of the Address Resolution Protocol.

     anycast         (inet6 only) Set the IPv6 anycast address bit.

     -anycast        (inet6 only) Clear the IPv6 anycast address bit.

     broadcast mask  (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.

     carpdev iface   If the driver is a carp(4) pseudo-device, attach it to
                     iface.  If not specified, the kernel will attempt to
                     select an interface with a subnet matching that of the
                     carp interface.

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

     -debug          Disable driver dependent debugging code.

     delete          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.  delete does not work for IPv6 addresses.
                     Use -alias with explicit IPv6 address instead.

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

     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.

     ipdst           This is used to specify an Internet host who is willing
                     to receive ip packets encapsulating NS packets bound for
                     a remote network.  An apparent point to point link is
                     constructed, and the address specified will be taken as
                     the NS address and network of the destination.  IP
                     encapsulation of CLNP packets is done differently.

     media type      Set the media type of the interface to type.  Some
                     interfaces support the mutually exclusive use of one of
                     several different physical media connectors.  For
                     example, a 10Mb/s Ethernet interface might support the
                     use of either AUI or twisted pair connectors.  Setting
                     the media type to ``10base5'' or ``AUI'' would change the
                     currently active connector to the AUI port.  Setting it
                     to ``10baseT'' or ``UTP'' would activate twisted pair.
                     Refer to the interfaces' driver specific man page for a
                     complete list of the available types and the ifmedia(4)
                     manual page for a list of media types.  See the -m flag
                     below.

     mediaopt opts   Set the specified media options on the interface.  opts
                     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.  Also see
                     the ifmedia(4) manual page for a list of media options.

     -mediaopt opts  Disable the specified media options on the interface.

     mode mode       If the driver supports the media selection system, set
                     the specified 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.

     instance minst  Set the media instance to minst.  This is useful for
                     devices which have multiple physical layer interfaces
                     (PHYs).  Setting the instance on such devices may not be
                     strictly required by the network interface driver as the
                     driver may take care of this automatically; see the
                     driver's manual page for more information.

     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.
                     Most interfaces don't support this option.

     netmask mask    (inet, inet6, and ISO) Specify how much of the address to
                     reserve for subdividing networks into sub-networks.  The
                     mask includes the network part of the local address and
                     the subnet part, which is taken from the host field of
                     the address.  The mask can be specified 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.

                     For INET and INET6 addresses, the netmask can also be
                     given with slash-notation after the address (e.g
                     192.168.17.3/24).

     nsellength n    (ISO only) This specifies a trailing number of bytes for
                     a received NSAP used for local identification, the
                     remaining leading part of which is taken to be the NET
                     (Network Entity Title).  The default value is 1, which is
                     conformant to US GOSIP.  When an ISO address is set in an
                     ifconfig command, it is really the NSAP which is being
                     specified.  For example, in US GOSIP, 20 hex digits
                     should be specified in the ISO NSAP to be assigned to the
                     interface.  There is some evidence that a number
                     different from 1 may be useful for AFI 37 type addresses.

     state state     Explicitly force the carp(4) pseudo-device to enter this
                     state.  Valid states are init, backup, and master.

     frag threshold  (IEEE 802.11 devices only) Configure the fragmentation
                     threshold for IEEE 802.11-based wireless network
                     interfaces.

     rts threshold   (IEEE 802.11 devices only) Configure the RTS/CTS
                     threshold for IEEE 802.11-based wireless network
                     interfaces.  This controls the number of bytes used for
                     the RTS/CTS handshake boundary.  The threshold can be any
                     value between 0 and 2347.  The default is 2347, which
                     indicates the RTS/CTS mechanism should not be used.

     ssid id         (IEEE 802.11 devices only) Configure the Service Set
                     Identifier (a.k.a. the network name) for IEEE
                     802.11-based wireless network interfaces.  The id can
                     either be any text string up to 32 characters in length,
                     or a series of up to 64 hexadecimal digits preceded by
                     ``0x''.  Setting id to the empty string allows the
                     interface to connect to any available access point.

     nwid id         Synonym for ``ssid''.

     hidessid        (IEEE 802.11 devices only) When operating as an access
                     point, do not broadcast the SSID in beacon frames or
                     respond to probe request frames unless they are directed
                     to the ap (i.e., they include the ap's SSID).  By
                     default, the SSID is included in beacon frames and
                     undirected probe request frames are answered.

     -hidessid       (IEEE 802.11 devices only) When operating as an access
                     point, broadcast the SSID in beacon frames and answer and
                     respond to undirected probe request frames (default).

     nwkey key       (IEEE 802.11 devices only) Enable WEP encryption for IEEE
                     802.11-based wireless network interfaces with the key.
                     The key can either be a string, a series of hexadecimal
                     digits preceded by ``0x'', or a set of keys in the form
                     n:k1,k2,k3,k4, where n specifies which of keys will be
                     used for all transmitted packets, and four keys, k1
                     through k4, are configured as WEP keys.  Note that the
                     order must be match within same network if multiple keys
                     are used.  For IEEE 802.11 wireless network, the length
                     of each key is restricted to 40 bits, i.e. 5-character
                     string or 10 hexadecimal digits, while the WaveLAN/IEEE
                     Gold cards accept the 104 bits (13 characters) key.

     nwkey persist   (IEEE 802.11 devices only) Enable WEP encryption for IEEE
                     802.11-based wireless network interfaces with the
                     persistent key written in the network card.

     nwkey persist:key
                     (IEEE 802.11 devices only) Write the key to the
                     persistent memory of the network card, and enable WEP
                     encryption for IEEE 802.11-based wireless network
                     interfaces with the key.

     -nwkey          (IEEE 802.11 devices only) Disable WEP encryption for
                     IEEE 802.11-based wireless network interfaces.

     apbridge        (IEEE 802.11 devices only) When operating as an access
                     point, pass packets between wireless clients directly
                     (default).

     -apbridge       (IEEE 802.11 devices only) When operating as an access
                     point, pass packets through the system so that they can
                     be forwared using some other mechanism.  Disabling the
                     internal bridging is useful when traffic is to be
                     processed with packet filtering.

     pass passphrase
                     If the driver is a carp(4) pseudo-device, set the
                     authentication key to passphrase.  There is no passphrase
                     by default

     powersave       (IEEE 802.11 devices only) Enable 802.11 power saving
                     mode.

     -powersave      (IEEE 802.11 devices only) Disable 802.11 power saving
                     mode.

     powersavesleep duration
                     (IEEE 802.11 devices only) Set the receiver sleep
                     duration in milliseconds for 802.11 power saving mode.

     bssid bssid     (IEEE 802.11 devices only) Set the desired BSSID for IEEE
                     802.11-based wireless network interfaces.

     -bssid          (IEEE 802.11 devices only) Unset the desired BSSID for
                     IEEE 802.11-based wireless network interfaces.  The
                     interface will automatically select a BSSID in this mode,
                     which is the default.

     chan chan       (IEEE 802.11 devices only) Select the channel (radio
                     frequency) to be used for IEEE 802.11-based wireless
                     network interfaces.

     -chan           (IEEE 802.11 devices only) Unset the desired channel to
                     be used for IEEE 802.11-based wireless network
                     interfaces.  It doesn't affect the channel to be created
                     for IBSS or hostap mode.

     list scan       (IEEE 802.11 devices only) Display the access points
                     and/or ad-hoc neighbors located in the vicinity.  The -v
                     flag may be used to display long SSIDs.  -v also causes
                     received information elements to be displayed
                     symbolically.  Only the super-user can use this command.

     tunnel src_addr[,src_port]
                     dest_addr[,dest_port] (IP tunnel devices only) Configure
                     the physical source and destination address for IP tunnel
                     interfaces, including gif(4).  The arguments src_addr and
                     dest_addr are interpreted as the outer source/destination
                     for the encapsulating IPv4/IPv6 header.

                     On a gre(4) interface in UDP mode, the arguments src_port
                     and dest_port are interpreted as the outer
                     source/destination port for the encapsulating UDP header.

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

     create          Create the specified network pseudo-device.

     destroy         Destroy the specified network pseudo-device.

     pltime n        (inet6 only) Set preferred lifetime for the address.

     prefixlen n     (inet and inet6 only) Effect is similar to netmask.  but
                     you can specify by prefix length by digits.

     deprecated      (inet6 only) Set the IPv6 deprecated address bit.

     -deprecated     (inet6 only) Clear the IPv6 deprecated address bit.

     tentative       (inet6 only) Set the IPv6 tentative address bit.

     -tentative      (inet6 only) Clear the IPv6 tentative address bit.

     eui64           (inet6 only) Fill interface index (lowermost 64bit of an
                     IPv6 address) automatically.

     link[0-2]       Enable special processing of the link level of the
                     interface.  These three options are interface specific in
                     actual effect, however, they are in general used to
                     select special modes of operation.  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.

     -link[0-2]      Disable special processing at the link level with the
                     specified interface.

     linkstr         Set a link-level string parameter for the interface.
                     This functionality varies from interface to interface.
                     Refer to the man page for the specific driver for more
                     information.

     -linkstr        Remove an interface link-level string parameter.

     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.

     vhid n          If the driver is a carp(4) pseudo-device, set the virtual
                     host ID to n.  Acceptable values are 1 to 255.

     vlan vid        If the interface is a vlan(4) pseudo-interface, set the
                     VLAN identifier to vid.  These are the first 12 bits
                     (0-4095) from a 16-bit integer used to create an 802.1Q
                     VLAN header for packets sent from the vlan(4) interface.
                     Note that vlan and vlanif must be set at the same time.

     vlanif iface    If the interface is a vlan(4) pseudo-interface, associate
                     the 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
                     encapsulation received by the physical interface with the
                     correct VLAN tag will be diverted to the associated
                     vlan(4) pseudo-interface.  The VLAN interface is assigned
                     a copy of the physical interface's flags and Ethernet
                     address.  If the vlan(4) 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 that
                     vlanif and vlan must be set at the same time.

     agrport iface   Add iface to the agr(4) interface.

     -agrport iface  Remove iface from the agr(4) interface.

     vltime n        (inet6 only) Set valid lifetime for the address.

     ip4csum         Shorthand of ``ip4csum-tx ip4csum-rx''

     -ip4csum        Shorthand of ``-ip4csum-tx -ip4csum-rx''

     tcp4csum        Shorthand of ``tcp4csum-tx tcp4csum-rx''

     -tcp4csum       Shorthand of ``-tcp4csum-tx -tcp4csum-rx''

     udp4csum        Shorthand of ``udp4csum-tx udp4csum-rx''

     -udp4csum       Shorthand of ``-udp4csum-tx -udp4csum-rx''

     tcp6csum        Shorthand of ``tcp6csum-tx tcp6csum-rx''

     -tcp6csum       Shorthand of ``-tcp6csum-tx -tcp6csum-rx''

     udp6csum        Shorthand of ``udp6csum-tx udp6csum-rx''

     -udp6csum       Shorthand of ``-udp6csum-tx -udp6csum-rx''

     ip4csum-tx      Enable hardware-assisted IPv4 header checksums for the
                     out-bound direction.

     -ip4csum-tx     Disable hardware-assisted IPv4 header checksums for the
                     out-bound direction.

     ip4csum-rx      Enable hardware-assisted IPv4 header checksums for the
                     in-bound direction.

     -ip4csum-rx     Disable hardware-assisted IPv4 header checksums for the
                     in-bound direction.

     tcp4csum-tx     Enable hardware-assisted TCP/IPv4 checksums for the out-
                     bound direction.

     -tcp4csum-tx    Disable hardware-assisted TCP/IPv4 checksums for the out-
                     bound direction.

     tcp4csum-rx     Enable hardware-assisted TCP/IPv4 checksums for the in-
                     bound direction.

     -tcp4csum-rx    Disable hardware-assisted TCP/IPv4 checksums for the in-
                     bound direction.

     udp4csum-tx     Enable hardware-assisted UDP/IPv4 checksums for the out-
                     bound direction.

     -udp4csum-tx    Disable hardware-assisted UDP/IPv4 checksums for the out-
                     bound direction.

     udp4csum-rx     Enable hardware-assisted UDP/IPv4 checksums for the in-
                     bound direction.

     -udp4csum-rx    Disable hardware-assisted UDP/IPv4 checksums for the in-
                     bound direction.

     tcp6csum-tx     Enable hardware-assisted TCP/IPv6 checksums for the out-
                     bound direction.

     -tcp6csum-tx    Disable hardware-assisted TCP/IPv6 checksums for the out-
                     bound direction.

     tcp6csum-rx     Enable hardware-assisted TCP/IPv6 checksums for the in-
                     bound direction.

     -tcp6csum-rx    Disable hardware-assisted TCP/IPv6 checksums for the in-
                     bound direction.

     udp6csum-tx     Enable hardware-assisted UDP/IPv6 checksums for the out-
                     bound direction.

     -udp6csum-tx    Disable hardware-assisted UDP/IPv6 checksums for the out-
                     bound direction.

     udp6csum-rx     Enable hardware-assisted UDP/IPv6 checksums for the in-
                     bound direction.

     -udp6csum-rx    Disable hardware-assisted UDP/IPv6 checksums for the in-
                     bound direction.

     tso4            Enable hardware-assisted TCP/IPv4 segmentation on
                     interfaces that support it.

     -tso4           Disable hardware-assisted TCP/IPv4 segmentation on
                     interfaces that support it.

     tso6            Enable hardware-assisted TCP/IPv6 segmentation on
                     interfaces that support it.

     -tso6           Disable hardware-assisted TCP/IPv6 segmentation on
                     interfaces that support it.

     maxupd n        If the driver is a pfsync(4) pseudo-device, indicate the
                     maximum number of updates for a single state which can be
                     collapsed into one.  This is an 8-bit number; the default
                     value is 128.

     syncdev iface   If the driver is a pfsync(4) pseudo-device, use the
                     specified interface to send and receive pfsync state
                     synchronisation messages.

     -syncdev        If the driver is a pfsync(4) pseudo-device, stop sending
                     pfsync state synchronisation messages over the network.

     syncpeer peer_address
                     If the driver is a pfsync(4) pseudo-device, make the
                     pfsync link point-to-point rather than using multicast to
                     broadcast the state synchronisation messages.  The
                     peer_address is the IP address of the other host taking
                     part in the pfsync cluster.  With this option, pfsync(4)
                     traffic can be protected using ipsec(4).

     -syncpeer       If the driver is a pfsync(4) pseudo-device, broadcast the
                     packets using multicast.

     ifconfig 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 protocol family.

     If the -s flag is passed before an interface name, ifconfig will attempt
     to query the interface for its media status.  If the interface supports
     reporting media status, and it reports that it does not appear to be
     connected to a network, ifconfig will exit with status of 1 (false);
     otherwise, it will exit with a zero (true) exit status.  Not all
     interface drivers support media status reporting.

     If the -m flag is passed before an interface name, ifconfig will display
     all of the supported media for the specified interface.  If the -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.  This is also the default behaviour when no arguments are
     given to ifconfig on the command line.  When -a is used, the output can
     be modified by adding more flags: -d limits this to interfaces that are
     down, -u limits this to interfaces that are up, -b limits this to
     broadcast interfaces, and -s omits interfaces which appear not to be
     connected to a network.

     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), -u (only list interfaces that are up), -s
     (only list interfaces that may be connected), -b (only list broadcast
     interfaces).

     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.

     The -v flag prints statistics on packets sent and received on the given
     interface.  If -h is used in conjunction with -v, the byte statistics
     will be printed in "human-readable" format.  The -z flag is identical to
     the -v flag except that it zeros the interface input and output
     statistics after printing them.

     The -N flag is just the opposite of the -n flag in netstat(1) or in
     route(8): it tells ifconfig to try to resolve numbers to hostnames or to
     service names.  The default ifconfig behavior is to print numbers instead
     of names.

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

EXAMPLES
     Add a link-layer (MAC) address to an Ethernet:

     ifconfig sip0 link 00:11:22:33:44:55

     Add and activate a link-layer (MAC) address:

     ifconfig sip0 link 00:11:22:33:44:55 active

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.

SEE ALSO
     netstat(1), agr(4), carp(4), ifmedia(4), netintro(4), pfsync(4), vlan(4),
     ifconfig.if(5), rc(8), routed(8)

HISTORY
     The ifconfig command appeared in 4.2BSD.

NetBSD 6.1.5                   January 28, 2012                   NetBSD 6.1.5