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

NAME
     ifconfig - configure network interface parameters

SYNOPSIS
     ifconfig interface address_family [address [dest_address]] [parameters]
     ifconfig tunnel-interface tunnel src_address dest_address
     ifconfig tunnel-interface deletetunnel
     ifconfig vlan-interface vlan vlan-tag vlandev parent-interface
     ifconfig interface [address_family]
     ifconfig -m interface [address_family]
     ifconfig [-a | -am] [address_family]
     ifconfig [-A | -Am] [address_family]

DESCRIPTION
     The ifconfig utility 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.  To configure a bridge interface,
     use the brconfig(8) program instead.

     The operands are as follows:

     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) and Internetwork Packet Exchange
             families, addresses are net:a.b.c.d.e.f, where net is the as-
             signed 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 consec-
             utive 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.  AppleTalk (LLAP) addresses are specified as
             nn.na (Network Number.Node Address).  Node addresses are divided
             into 2 classes: User Node IDs and Server Node IDs. 1-127($01-$7F)
             are for User Node IDs while 128-254($80-$FE) are used for Server
             Node IDs.  Node 0($00) is not allowed (unknown) while Node
             255($FF) is reserved for the AppleTalk broadcast Hardware address
             (broadcast ID).

     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'', ``ipx'', 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 addr  (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.

     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
                     automatically disables routes using the interface.

     tunnel src_address dest_address
                     Set the source and destination tunnel addresses on a tun-
                     nel interface, including gif(4). Packets routed to this
                     interface will be encapsulated in IPv4 or IPv6, depending
                     on the source and destination address families.  Both ad-
                     dresses must be of the same family.

     deletetunnel    Removes the source and dsetination tunnel addresses, con-
                     figured onto a tunnel 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 encap-
                     sulation of CLNP packets is done differently.

     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.

     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.

     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 phys-
                     ical interface iface with it. Packets transmitted through
                     the vlan interface will be diverted to the specified
                     physical interface iface with 802.1Q vlan encapsulation.
                     Packets with 802.1Q encapsulation 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 al-
                     ready 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 interface that the parent interface supports in-
                     sertion and extraction of vlan tags on its own (usually
                     in firmware) and that it should pass packets to and from
                     the parent unaltered.

     -vlandev        If the driver is a vlan pseudo device, disassociate the
                     physical interface 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.

     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.

     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, specifically ray(4))
                     Configure network ID for IEEE 802.11-based wireless net-
                     work interfaces.

     phase           The argument following this specifies the version (phase)
                     of the AppleTalk network attached to the interface.  Val-
                     ues of 1 or 2 are permitted.

     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.

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

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

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

     trailers        Request the use of a ``trailer'' link level encapsulation
                     when sending (default).  If a network interface supports
                     trailers, the system will, when possible, encapsulate
                     outgoing messages in a manner which minimizes the number
                     of memory to memory copy operations performed by the re-
                     ceiver.  On networks that support the Address Resolution
                     Protocol (see arp(4); currently, only Ethernet), this
                     flag indicates that the system should request that other
                     systems use trailers when sending to this host.  Similar-
                     ly, trailer encapsulations will be sent to other hosts
                     that have made such requests.  Currently used by Internet
                     protocols only.

     -trailers       Disable the use of a ``trailer'' link level encapsula-


                     tion.

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

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

     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.

     Using -a causes ifconfig to print information on all interfaces.  The
     protocol family may be specified as well.  Additionally, if -am, is used,
     interface media information is printed.

     If -A is used, it causes full interface alias information for each inter-
     face to be displayed.  If -Am is used, interface media information is
     printed for all interfaces as well.

     If -m followed by an interface name is specified, then the media informa-
     tion for that interface will be printed.

     Only the superuser may modify the configuration of a network interface.

EXAMPLES
     ifconfig fxp0 inet 192.168.1.10 netmask 255.255.255.0
               Assign the inet(4) address of 192.168.1.10 with a network mask
               of 255.255.255.0 to interface fxp0.

     ifconfig fxp0 ipx 12625920
               Assign the ipx(3) address of 12625920 specified in decimal to
               interface fxp0.

     ifconfig fxp0 atalk 39108.128 range 39107-39109 phase 2
               Assign the AppleTalk network 39108 and server node 128 with a
               network range of 39107-39109 to interface fxp0 on a phase 2 Ap-
               pleTalk network.

     ifconfig xl0 media 10baseT
               Configure the xl0 interface to use 10baseT.

     ifconfig xl0 media 100baseTX mediaopt full-duplex
               Configure the xl0 interface to use 100baseTX, full duplex.

     ifconfig vlan0 192.168.254.1 vlan 4 vlandev fxp0
               Configure the vlan0 interface for IP address 192.168.254.1,
               vlan tag 4, and vlan parent device fxp0.

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), hostname.if(5), brconfig(8), rc(8),
     routed(8)

HISTORY
     The ifconfig command appeared in 4.2BSD.

OpenBSD 2.9                    September 3, 1998                             5
