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NAME    [Toc]    [Back]

     ifconfig - configure network interface parameters

SYNOPSIS    [Toc]    [Back]

     ifconfig interface [address_family] [address [dest_address]]
     ifconfig -A | -Am | -a | -am [address_family]
     ifconfig -C
     ifconfig -m interface [address_family]
     ifconfig interface create
     ifconfig interface destroy
     ifconfig carp-interface vhid host-id
     ifconfig pfsync-interface syncpeer peer_address syncif iface
     ifconfig tunnel-interface tunnel src_address dest_address
     ifconfig tunnel-interface deletetunnel
     ifconfig    vlan-interface     vlan     vlan-tag     vlandev
     ifconfig interface group group-name

DESCRIPTION    [Toc]    [Back]

     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
     address  or  other  operating  parameters.   To  configure a
bridge interface,
     use the brconfig(8) program instead.

     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.

     Only the superuser may modify the configuration of a network

     The options are as follows:

     -A      Causes full interface alias information for each interface to be

     -Am      The  same as the -A option, but additionally prints
interface media
 information for all interfaces.

     -a      Causes ifconfig to print information on  all  interfaces.  The protocol
 family may be specified as well.

     -am      The  same as the -a option, but additionally prints
interface media
 information for all interfaces.

     -C      Print the names of all network  pseudo-devices  that
can be created
             dynamically at runtime using ifconfig create.

     -m interface
             Print media information for a given interface.

             For the DARPA Internet family, the address is either
a host name
             present in the host name database,  hosts(5),  or  a
DARPA Internet
             address expressed in the Internet standard ``dot notation''.

             Internet version 6 addresses are either a host  name
present in
             the  host  name  database,  hosts(5), or an Internet
version 6 address
 in standard colon separated form, as described
in the
             inet(3) manual page.

             For  the  Xerox Network Systems(tm) and Internetwork
Packet Exchange
  families,  addresses   are   of   the   form
             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.

             AppleTalk   (LLAP)   addresses   are   specified  as
``nn.na'' (``Network
             Number.Node Address'').  Node addresses are  divided
into two
             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

             IPX  addresses are specified as listed in the ipx(3)
manual page.

             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'', ``ipx'', and ``ns''.

             The  interface  parameter  is  a  string of the form
``name unit'',
             for example, ``en0''.  If no optional parameters are
             this  string  can instead be just ``name''.  In this
case, all interfaces
 of that type will be displayed.  For  example, ``carp''
             will   display  the  current  configuration  of  all
carp(4) interfaces.

     The following parameters may be set with ifconfig:

     802.2 802.2tr 802.3 snap EtherII
                     Set the  ipx(3)  frame  type  to  be  either
802.2, 802.2tr,
                     802.3, snap, or Ethernet II.

     advbase  n        If  the driver is a carp(4) pseudo-device,
set the base
                     advertisement interval to n  seconds.   This
is 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 and advskew indicate how frequently,
 in seconds, the host will advertise
the fact
                     that  it considers itself master of the virtual host.  The
                     formula is advbase + (advskew / 255  ).   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.

     anycast         (inet6 only) Set the  IPv6  anycast  address

     -anycast         (inet6 only) Clear the IPv6 anycast address

     arp             Enable the use  of  the  Address  Resolution
                     (``ARP'';  see  arp(4))  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 ARP.

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

     create           Create the specified network pseudo-device.
At least the
                     following devices can be created on demand:

                     bridge(4), carp(4), gif(4),  gre(4),  lo(4),
ppp(4), sl(4),
                     tun(4), vlan(4)

     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.

     deletetunnel     Removes  the  source and destination tunnel
addresses, configured
 onto a tunnel interface.

     description value
                     Specify  a  description  of  the  interface.
This can be used
                     to label interfaces in situations where they
may otherwise
 be difficult to distinguish.

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

     destroy         Destroy the specified network pseudo-device.

     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
                     automatically disables routes using the  interface.

     group group-name
                     Assign  the  interface  to a ``group''.  Any
interface can
                     be in multiple groups.  Interface groups are
described in

     -group group-name
                     Remove   the   interface   from   the  given

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

     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.

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

     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.

     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.

     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
                     ``10baseT'' or ``UTP'' would activate twisted pair.  Refer
 to the interface's  driver-specific  man
page for a
                     complete list of the available types, or use

                           $ ifconfig -m interface

                     for a listing of choices.

     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  interface's  driverspecific man
                     page  for  a  complete list of available options, or use

                           $ ifconfig -m interface

                     for a listing of choices.

     -mediaopt opts  Disable the specified media options  on  the

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

     mtu value       Set the MTU for this  device  to  the  given
value.  Cloned
                     routes will inherit this value as a default.

     netmask mask    (inet and inet6) Specify how much of the address to reserve
  for subdividing networks into subnetworks.  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
                     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.

     nwid id         (IEEE 802.11 devices only) Configure network
                     802.11-based  wireless  network  interfaces.
The id can either
 be any text string up to 32  characters
in length, or
                     a series of hexadecimal digits up to 64 digits.  The empty
 string allows the interface to connect to
any available
 access points.

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

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

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

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

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

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

     pltime n        (inet6 only) Set preferred lifetime for  the

     powersave        (IEEE  802.11  devices  only) Enable 802.11
power saving

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

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

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

     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
OpenBSD implements
                     it internally as a set of netmasks.

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

     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.

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

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

     tentative        (inet6 only) Set the IPv6 tentative address

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

     timeslot timeslot_range
                     Set the timeslot range map, which is used to
                     which channels an interface device uses.

     tunnel src_address dest_address
                     Set the source and  destination  tunnel  addresses on a tunnel
  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 addresses
 must be of the same family.

     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

     vlan vlan_tag   If the interface is a vlan(4)  pseudo-interface, set the
                     vlan tag value to vlan_tag.  This value is a
12-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(4) pseudo-device,
                     physical  interface  iface with it.  Packets
                     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
                     flags and  the  parent's  Ethernet  address.
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;
link0 tells the
                     vlan  interface  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        If the driver is  a  vlan(4)  pseudo-device,
                     the physical interface from it.  This breaks
the link between
 the vlan  interface  and  its  parent,
clears its vlan
                     tag,  flags, and link address, and shuts the

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

EXAMPLES    [Toc]    [Back]

     Assign  the  inet(3)  address of with a network
mask of to interface fxp0:

           #   ifconfig   fxp0    inet    netmask

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

           # ifconfig fxp0 ipx 12625920

     Assign the AppleTalk network 39108 and server node 128  with
a network
     range  of  39107-39109  to  interface  fxp0 on a phase 2 AppleTalk network:

           # ifconfig  fxp0  atalk  39108.128  range  39107-39109
phase 2

     Configure the xl0 interface to use 10baseT:

           # ifconfig xl0 media 10baseT

     Configure the xl0 interface to use 100baseTX, full duplex:

           # ifconfig xl0 media 100baseTX mediaopt full-duplex

     Label the em0 interface as an uplink:

           #  ifconfig  em0 description "Uplink to Gigabit Switch

     Configure the vlan0 interface for IP address,
vlan tag 4,
     and vlan parent device fxp0:

           # ifconfig vlan0 vlan 4 vlandev fxp0

     Configure  the  carp0 interface for IP address,
virtual host
     ID 1:

           # ifconfig carp0 vhid 1

     Create the gif1 network interface:

           # ifconfig gif1 create

     Destroy the gif1 network interface:

           # ifconfig gif1 destroy

DIAGNOSTICS    [Toc]    [Back]

     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    [Toc]    [Back]

     netstat(1), inet(3),  ipx(3),  arp(4),  bridge(4),  carp(4),
gif(4), gre(4),
     ifmedia(4),  inet(4), lo(4), netintro(4), pfsync(4), ppp(4),
     tun(4), vlan(4), hostname.if(5), hosts(5), networks(5),  brconfig(8),
     rc(8), routed(8)

HISTORY    [Toc]    [Back]

     The ifconfig command appeared in 4.2BSD.

OpenBSD      3.6                        September     3,     1998
[ Back ]
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