freebsd/sbin/ifconfig/ifconfig.8

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.\"     From: @(#)ifconfig.8	8.3 (Berkeley) 1/5/94
.\" $FreeBSD$
.\"
.Dd July 26, 2004
.Dt IFCONFIG 8
.Os
.Sh NAME
.Nm ifconfig
.Nd configure network interface parameters
.Sh SYNOPSIS
.Nm
.Op Fl L
.Op Fl m
.Ar interface
.Op Cm create
.Op Ar address_family
.Oo
.Ar address
.Op Ar dest_address
.Oc
.Op Ar parameters
.Nm
.Ar interface
.Cm destroy
.Nm
.Fl a
.Op Fl L
.Op Fl d
.Op Fl m
.Op Fl u
.Op Ar address_family
.Nm
.Fl l
.Op Fl d
.Op Fl u
.Op Ar address_family
.Nm
.Op Fl L
.Op Fl d
.Op Fl m
.Op Fl u
.Op Fl C
.Sh DESCRIPTION
The
.Nm
utility is used to assign an address
to a network interface and/or configure
network interface parameters.
The
.Nm
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.
.Pp
The following options are available:
.Bl -tag -width indent
.It Ar address
For the
.Tn DARPA Ns -Internet
family,
the address is either a host name present in the host name data
base,
.Xr hosts 5 ,
or a
.Tn DARPA
Internet address expressed in the Internet standard
.Dq dot notation .
.Pp
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
.Li 192.168.0.1/16 .
.Pp
For
.Dq inet6
family, it is also possible to specify the prefix length using the slash
notation, like
.Li ::1/128 .
See the
.Cm prefixlen
parameter below for more information.
.\" For the Xerox Network Systems(tm) family,
.\" addresses are
.\" .Ar net:a.b.c.d.e.f ,
.\" where
.\" .Ar net
.\" is the assigned network number (in decimal),
.\" and each of the six bytes of the host number,
.\" .Ar a
.\" through
.\" .Ar f ,
.\" are specified in hexadecimal.
.\" The host number may be omitted on IEEE 802 protocol
.\" (Ethernet, FDDI, and Token Ring) interfaces,
.\" which use the hardware physical address,
.\" and on interfaces other than the first.
.\" For the
.\" .Tn 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.
.Pp
The link-level
.Pq Dq 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.
.It Ar address_family
Specify 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
.Dq inet ,
.Dq inet6 ,
.Dq atalk ,
.Dq ipx ,
.\" .Dq iso ,
and
.Dq link .
.\" and
.\" .Dq ns .
The default is
.Dq inet .
.Dq ether
and
.Dq lladdr
are synonyms for
.Dq link .
.It Ar dest_address
Specify the address of the correspondent on the other end
of a point to point link.
.It Ar interface
This
parameter is a string of the form
.Dq name unit ,
for example,
.Dq Li ed0 .
.El
.Pp
The following parameters may be set with
.Nm :
.Bl -tag -width indent
.It Cm add
Another name for the
.Cm alias
parameter.
Introduced for compatibility
with
.Bsx .
.It Cm 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.
If the address is on the same subnet as the first network address
for this interface, a non-conflicting netmask must be given.
Usually
.Li 0xffffffff
is most appropriate.
.It Fl 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.
.It Cm 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.
.It Cm arp
Enable the use of the Address Resolution Protocol
.Pq Xr arp 4
in mapping
between network level addresses and link level addresses (default).
This is currently implemented for mapping between
.Tn DARPA
Internet
addresses and
.Tn IEEE
802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses).
.It Fl arp
Disable the use of the Address Resolution Protocol
.Pq Xr arp 4 .
.It Cm staticarp
If the Address Resolution Protocol is enabled,
the host will only reply to requests for its addresses,
and will never send any requests.
.It Fl staticarp
If the Address Resolution Protocol is enabled,
the host will perform normally,
sending out requests and listening for replies.
.It Cm 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.
.It Cm debug
Enable driver dependent debugging code; usually, this turns on
extra console error logging.
.It Fl debug
Disable driver dependent debugging code.
.It Cm promisc
Put interface into permanently promiscuous mode.
.It Fl promisc
Disable permanently promiscuous mode.
.It Cm delete
Another name for the
.Fl alias
parameter.
.It Cm down
Mark an interface
.Dq down .
When an interface is marked
.Dq 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.
.It Cm eui64
(Inet6 only.)
Fill interface index
(lowermost 64bit of an IPv6 address)
automatically.
.It Cm ipdst
This is used to specify an Internet host who is willing to receive
IP packets encapsulating IPX packets bound for a remote network.
An apparent point to point link is constructed, and
the address specified will be taken as the IPX address and network
of the destination.
.It Cm maclabel Ar label
If Mandatory Access Control support is enabled in the kernel,
set the MAC label to
.Ar label .
.\" (see
.\" .Xr maclabel 7 ) .
.It Cm media Ar type
If the driver supports the media selection system, set the media type
of the interface to
.Ar 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
.Tn AUI
or twisted pair connectors.
Setting the media type to
.Dq Li 10base5/AUI
would change the currently active connector to the AUI port.
Setting it to
.Dq Li 10baseT/UTP
would activate twisted pair.
Refer to the interfaces' driver
specific documentation or man page for a complete list of the
available types.
.It Cm mediaopt Ar opts
If the driver supports the media selection system, set the specified
media options on the interface.
The
.Ar 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.
.It Fl mediaopt Ar opts
If the driver supports the media selection system, disable the
specified media options on the interface.
.It Cm mode Ar mode
If the driver supports the media selection system, set the specified
operating mode on the interface to
.Ar mode .
For IEEE 802.11 wireless interfaces that support multiple operating modes
this directive is used to select between 802.11a
.Pq Dq Li 11a ,
802.11b
.Pq Dq Li 11b ,
and 802.11g
.Pq Dq Li 11g
operating modes.
.It Cm name Ar name
Set the interface name to
.Ar name .
.It Cm rxcsum , txcsum
If the driver supports user-configurable checksum offloading,
enable receive (or transmit) checksum offloading on the interface.
Some drivers may not be able to enable these flags independently
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.
.It Fl rxcsum , Fl txcsum
If the driver supports user-configurable checksum offloading,
disable receive (or transmit) checksum offloading on the interface.
These settings may not always be independent of each other.
.It Cm polling
If the driver has user-configurable
.Xr polling 4
support, select the polling mode on the interface.
.It Fl polling
If the driver has user-configurable
.Xr polling 4
support, select the interrupt mode on the interface.
.It Cm tunnel Ar src_addr dest_addr
(IP tunnel devices only.)
Configure the physical source and destination address for IP tunnel
interfaces
.Pq Xr gif 4 .
The arguments
.Ar src_addr
and
.Ar dest_addr
are interpreted as the outer source/destination for the encapsulating
IPv4/IPv6 header.
.It Cm deletetunnel
Unconfigure the physical source and destination address for IP tunnel
interfaces previously configured with
.Cm tunnel .
.It Cm 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
.Nm
invocation.
.It Cm destroy
Destroy the specified network pseudo-device.
.It Cm plumb
Another name for the
.Cm create
parameter.
Included for
.Tn Solaris
compatibility.
.It Cm unplumb
Another name for the
.Cm destroy
parameter.
Included for
.Tn Solaris
compatibility.
.It Cm vlan Ar vlan_tag
If the interface is a
.Xr vlan 4
pseudo interface, set the VLAN tag value
to
.Ar vlan_tag .
This value is a 16-bit number which is used to create an 802.1Q
VLAN header for packets sent from the
.Xr vlan 4
interface.
Note that
.Cm vlan
and
.Cm vlandev
must both be set at the same time.
.It Cm vlandev Ar iface
If the interface is a
.Xr vlan 4
pseudo device, associate physical interface
.Ar iface
with it.
Packets transmitted through the
.Xr vlan 4
interface will be
diverted to the specified physical interface
.Ar 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
.Xr vlan 4
pseudo-interface.
The
.Xr vlan 4
interface is assigned a
copy of the parent interface's flags and the parent's ethernet address.
The
.Cm vlandev
and
.Cm vlan
must both be set at the same time.
If the
.Xr 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.
.Pp
Note: if the hardware tagging capability
is set on the parent interface, the
.Xr vlan 4
pseudo
interface's behavior changes:
the
.Xr 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.
.It Fl vlandev Ar iface
If the driver is a
.Xr vlan 4
pseudo device, disassociate the physical interface
.Ar iface
from it.
This breaks the link between the
.Xr vlan 4
interface and its parent,
clears its VLAN tag, flags and its link address and shuts the interface down.
.It Cm vlanmtu , vlanhwtag
If the driver offers user-configurable VLAN support, enable
reception of extended frames or tag processing in hardware,
respectively.
Note that this must be issued on a physical interface associated with
.Xr vlan 4 ,
not on a
.Xr vlan 4
interface itself.
.It Fl vlanmtu , Fl vlanhwtag
If the driver offers user-configurable VLAN support, disable
reception of extended frames or tag processing in hardware,
respectively.
.It Cm metric Ar n
Set the routing metric of the interface to
.Ar n ,
default 0.
The routing metric is used by the routing protocol
.Pq Xr 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.
.It Cm mtu Ar n
Set the maximum transmission unit of the interface to
.Ar 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 restrictions.
.It Cm netmask Ar mask
.\" (Inet and ISO.)
(Inet only.)
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
.Ql 0x ,
with a dot-notation Internet address,
or with a pseudo-network name listed in the network table
.Xr 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.
.Pp
The netmask can also be specified in CIDR notation after the address.
See the
.Ar address
option above for more information.
.It Cm prefixlen Ar len
(Inet6 only.)
Specify that
.Ar len
bits are reserved for subdividing networks into sub-networks.
The
.Ar 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 parameter is omitted, 64 is used.
.Pp
The prefix can also be specified using the slash notation after the address.
See the
.Ar address
option above for more information.
.\" see
.\" Xr eon 5 .
.\" .It Cm nsellength Ar n
.\" .Pf ( Tn ISO
.\" only)
.\" This specifies a trailing number of bytes for a received
.\" .Tn NSAP
.\" used for local identification, the remaining leading part of which is
.\" taken to be the
.\" .Tn NET
.\" (Network Entity Title).
.\" The default value is 1, which is conformant to US
.\" .Tn GOSIP .
.\" When an ISO address is set in an ifconfig command,
.\" it is really the
.\" .Tn NSAP
.\" which is being specified.
.\" For example, in
.\" .Tn US GOSIP ,
.\" 20 hex digits should be
.\" specified in the
.\" .Tn ISO NSAP
.\" to be assigned to the interface.
.\" There is some evidence that a number different from 1 may be useful
.\" for
.\" .Tn AFI
.\" 37 type addresses.
.It Cm range Ar netrange
Under appletalk, set the interface to respond to a
.Ar netrange
of the form
.Ar startnet Ns - Ns Ar endnet .
Appletalk uses this scheme instead of
netmasks though
.Fx
implements it internally as a set of netmasks.
.It Cm remove
Another name for the
.Fl alias
parameter.
Introduced for compatibility
with
.Bsx .
.It Cm phase
The argument following this specifies the version (phase) of the
Appletalk network attached to the interface.
Values of 1 or 2 are permitted.
.Sm off
.It Cm link Op Cm 0 No - Cm 2
.Sm on
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.
.Sm off
.It Fl link Op Cm 0 No - Cm 2
.Sm on
Disable special processing at the link level with the specified interface.
.It Cm monitor
Put the interface in monitor mode.
No packets are transmitted, and received packets are discarded after
.Xr bpf 4
processing.
.It Fl monitor
Take the interface out of monitor mode.
.It Cm up
Mark an interface
.Dq up .
This may be used to enable an interface after an
.Dq Nm Cm 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.
.It Cm ssid Ar 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
.Ql 0x .
Additionally, the SSID may be cleared by setting it to
.Ql - .
.It Cm nwid Ar ssid
Another name for the
.Cm ssid
parameter.
Included for
.Nx
compatibility.
.It Cm stationname Ar name
For IEEE 802.11 wireless interfaces, set the name of this station.
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.
.It Cm station Ar name
Another name for the
.Cm stationname
parameter.
Included for
.Bsx
compatibility.
.It Cm channel Ar 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.
.It Cm authmode Ar mode
For IEEE 802.11 wireless interfaces, set the desired authentication mode
in infrastructure mode.
Not all adaptors support all modes.
The set of
valid modes is
.Dq Li none ,
.Dq Li open ,
and
.Dq Li shared .
Modes are case insensitive.
.It Cm powersave
For IEEE 802.11 wireless interfaces, enable powersave mode.
.It Fl powersave
For IEEE 802.11 wireless interfaces, disable powersave mode.
.It Cm powersavesleep Ar sleep
For IEEE 802.11 wireless interfaces, set the desired max powersave sleep
time in milliseconds.
.It Cm protmode Ar technique
For IEEE 802.11 wireless interfaces operating in 11g, use the specified
.Ar technique
for protecting OFDM frames in a mixed 11b/11g network.
The set of valid techniques is
.Dq Li off ,
.Dq Li cts
(CTS to self),
and
.Dq Li rtscts
(RTS/CTS).
Technique names are case insensitive.
.It Cm rtsthreshold Ar length
For IEEE 802.11 wireless interfaces, set the threshold for which
transmitted frames are preceded by transmission of an
RTS
control frame.
The
.Ar 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.
.It Cm txpower Ar power
For IEEE 802.11 wireless interfaces, set the power used to transmit frames.
The
.Ar power
argument
is a unitless value in the range 0 to 100 that is interpreted
by drivers to derive a device-specific 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.
.It Cm wepmode Ar mode
For IEEE 802.11 wireless interfaces, set the desired WEP mode.
Not all adaptors support all modes.
The set of valid modes is
.Dq Li off ,
.Dq Li on ,
and
.Dq Li mixed .
The
.Dq Li mixed
mode explicitly tells the adaptor to allow association with access
points which allow both encrypted and unencrypted traffic.
On these adaptors,
.Dq Li on
means that the access point must only allow encrypted connections.
On other adaptors,
.Dq Li on
is generally another name for
.Dq Li mixed .
Modes are case insensitive.
.It Cm weptxkey Ar index
For IEEE 802.11 wireless interfaces, set the WEP key to be used for
transmission.
.It Cm wepkey Ar key Ns | Ns Ar index : Ns Ar key
For IEEE 802.11 wireless interfaces, set the selected WEP key.
If an
.Ar 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 network and the
capabilities of the adaptor.
It may be specified either as a plain
string or as a string of hexadecimal digits proceeded by
.Ql 0x .
For maximum portability, hex keys are recommended;
the mapping of text keys to WEP encryption is usually driver-specific.
In particular, the
.Tn Windows
drivers do this mapping differently to
.Fx .
A key may be cleared by setting it to
.Ql - .
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 permanent keys stored in NVRAM.
.It Cm wep
Another way of saying
.Cm wepmode on .
Included for
.Bsx
compatibility.
.It Fl wep
Another way of saying
.Cm wepmode off .
Included for
.Bsx
compatibility.
.It Cm nwkey key
Another way of saying:
.Pp
.Dq Li "wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey 4:-" .
.Pp
Included for
.Nx
compatibility.
.It Cm nwkey Xo
.Sm off
.Ar n : k1 , k2 , k3 , k4
.Sm on
.Xc
Another way of saying
.Pp
.Dq Li "wepmode on weptxkey n wepkey 1:k1 wepkey 2:k2 wepkey 3:k3 wepkey 4:k4" .
.Pp
Included for
.Nx
compatibility.
.It Fl nwkey
Another way of saying
.Cm wepmode off .
.Pp
Included for
.Nx
compatibility.
.El
.Pp
The
.Nm
utility displays the current configuration for a network interface
when no optional parameters are supplied.
If a protocol family is specified,
.Nm
will report only the details specific to that protocol family.
.Pp
If the
.Fl m
flag is passed before an interface name,
.Nm
will display the capability list and all
of the supported media for the specified interface.
If
.Fl L
flag is supplied, address lifetime is displayed for IPv6 addresses,
as time offset string.
.Pp
Optionally, the
.Fl a
flag may be used instead of an interface name.
This flag instructs
.Nm
to display information about all interfaces in the system.
The
.Fl d
flag limits this to interfaces that are down, and
.Fl u
limits this to interfaces that are up.
When no arguments are given,
.Fl a
is implied.
.Pp
The
.Fl 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
.Fl d
(only list interfaces that are down)
and
.Fl u
(only list interfaces that are up).
.Pp
The
.Fl 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.
.Pp
Only the super-user may modify the configuration of a network interface.
.Sh NOTES
The media selection system is relatively new and only some drivers support
it (or have need for it).
.Sh 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.
.Sh BUGS
Basic IPv6 node operation requires a link-local address on each
interface configured for IPv6.
Normally, such an address is automatically configured by the
kernel on each interface added to the system; this behaviour may
be disabled by setting the sysctl MIB variable
.Va net.inet6.ip6.auto_linklocal
to 0.
.Pp
If you delete such an address using
.Nm ,
the kernel may act very oddly.
Do this at your own risk.
.Sh SEE ALSO
.Xr netstat 1 ,
.Xr netintro 4 ,
.Xr vlan 4 ,
.\" .Xr eon 5 ,
.Xr rc 8 ,
.Xr routed 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
utility appeared in
.Bx 4.2 .