ifconfig(8)
- NetBSD Manual Pages
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 10Mb/s 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 (careful-
ly) 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 10Mb/s Eth-
ernet 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.
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 (IEEE 802.11 devices only) Disable WEP encryption for
IEEE 802.11-based wireless network interfaces.
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 (inet6 only) Effect is similar to netmask. but you can
specify by prefix length by digits.
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.
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.
4.2 Berkeley Distribution April 16, 1997 5
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