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

NAME
     ifconfig - configure network interface parameters

SYNOPSIS
     ifconfig interface address_family [address [dest_address]] [parameters]
     ifconfig [-mL] interface [protocol_family]
     ifconfig -a [-mL] [-b] [-d] [-u] [-s] [protocol_family]
     ifconfig -l [-b] [-d] [-u] [-s]
     ifconfig -s interface
     ifconfig -C

DESCRIPTION
     ifconfig is used to assign an address to a network interface and/or con-
     figure 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, ad-
             dresses are specified as a long hexadecimal string, as in the Xe-
             rox 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 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'', ``iso'', and ``ns''.

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

     The following parameters may be set with ifconfig:

     alias           Establish an additional network address for this inter-
                     face.  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 map-
                     ping between network level addresses and link level ad-
                     dresses (default).  This is currently implemented for
                     mapping between DARPA Internet addresses and Ethernet ad-
                     dresses.

     -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.

     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 mes-
                     sages through that interface.  If possible, the interface
                     will be reset to disable reception as well.  This action
                     does not automatically disable routes using the inter-
                     face.

     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 encap-
                     sulation of CLNP packets is done differently.

     media type      Set the media type of the interface to type.  Some inter-
                     faces support the mutually exclusive use of one of sever-
                     al 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 ac-
                     tive connector to the AUI port.  Setting it to
                     ``10baseT'' or ``UTP'' would activate twisted pair.  Re-
                     fer to the interfaces' driver specific man page for a
                     complete list of the available types.

     mediaopt opts   Set the specified media options on the interface.  opts
                     is a comma delimited list of options to apply to the in-
                     terface.  Refer to the interfaces' driver specific man
                     page for a complete list of available options.

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

     instance minst  Set the media instance to minst.  This is useful for de-
                     vices 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 driv-
                     er'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 hex-
                     adecimal 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 contigu-
                     ous 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 re-
                     maining 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 differ-
                     ent from 1 may be useful for AFI 37 type addresses.

     nwid id         (IEEE 802.11 devices only) Configure network ID for IEEE
                     802.11-based wireless network interfaces.  The id can ei-
                     ther be any text string up to 32 characters in length, or
                     a series of hexadecimal digits up to 64 digits.  The emp-
                     ty string allows the interface to connect to any avail-
                     able access points.

     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, or a set of keys in the form n:k1,k2,k3,k4, where
                     n specifies which of keys will be used for all transmit-
                     ted 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 dig-
                     its, 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 persis-
                     tent key written in the network card.

     nwkey persist:key
                     (IEEE 802.11 devices only) Write the key to the persis-
                     tent memory of the network card, and enable WEP encryp-
                     tion 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.

     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 dura-
                     tion in milliseconds for 802.11 power saving mode.

     tunnel src_addr dest_addr
                     (IP tunnel devices only) Configure the physical source
                     and destination address for IP tunnel interfaces (gif).
                     The arguments src_addr and dest_addr are interpreted as
                     the outer source/destination for the encapsulating
                     IPv4/IPv6 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.

     link[0-2]       Enable special processing of the link level of the inter-
                     face.  These three options are interface specific in ac-
                     tual effect, however, they are in general used to select
                     special modes of operation. An example of this is to en-
                     able 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.

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

     vlan tag        If the interface is a vlan(4) pseudo-interface, set the
                     VLAN tag to tag.  This 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 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 transmit-
                     ted through the vlan(4) interface will be diverted to the
                     specified physical interface iface with 802.1Q VLAN en-
                     capsulation.  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 in-
                     terface's flags and Ethernet address.  If the vlan(4) in-
                     terface 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.

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

     ip4csum         Enable hardware-assisted IPv4 header checksums on inter-
                     faces that support it.

     -ip4csum        Disable hardware-assisted IPv4 header checksums on inter-
                     faces that support it.

     tcp4csum        Enable hardware-assisted TCP/IPv4 checksums on interfaces
                     that support it.

     -tcp4csum       Disable hardware-assisted TCP/IPv4 checksums on inter-
                     faces that support it.

     udp4csum        Enable hardware-assisted UDP/IPv4 checksums on interfaces
                     that support it.

     -udp4csum       Disable hardware-assisted UDP/IPv4 checksums on inter-
                     faces that support it.

     tcp6csum        Enable hardware-assisted TCP/IPv6 checksums on interfaces
                     that support it.

     -tcp6csum       Disable hardware-assisted TCP/IPv6 checksums on inter-
                     faces that support it.

     udp6csum        Enable hardware-assisted UDP/IPv6 checksums on interfaces
                     that support it.

     -udp6csum       Disable hardware-assisted UDP/IPv6 checksums on inter-
                     faces that support it.

     tcp4csum-rx     Enable hardware-assisted TCP/IPv4 checksums on interfaces
                     that support it only for the in-bound direction.

     -tcp4csum-rx    Disable hardware-assisted TCP/IPv4 checksums on inter-
                     faces that support it only for the in-bound direction.

     udp4csum-rx     Enable hardware-assisted UDP/IPv4 checksums on interfaces
                     that support it only for the in-bound direction.

     -udp4csum-rx    Disable hardware-assisted UDP/IPv4 checksums on inter-
                     faces that support it only for the in-bound direction.

     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 con-
     nected to a network, ifconfig will exit with status of 1 (false); other-
     wise, 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.  -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 ex-
     clusive with all other flags and commands, except for -d (only list in-
     terfaces that are down), -u (only list interfaces that are up), -s (only
     list interfaces that may be connected), -b (only list broadcast inter-
     faces).

     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.

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), ifmedia(4), netintro(4), rc(8), routed(8)

HISTORY
     The ifconfig command appeared in 4.2BSD.

NetBSD 1.6                      April 27, 2001                               6

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