Configure network interface parameters
Syntax:
ifconfig interface address_family [address [dest_address]]
[parameters]
ifconfig [-hLmvz] interface [protocol_family]
ifconfig -a [-bdhLmsuvz] [protocol_family]
ifconfig -l [-b] [-d] [-u] [-s]
ifconfig -s interface
ifconfig -C
Options:
- -a
- Display information about all of the interfaces in the system.
You can use the -d, -u, -b, and
-s options with this option to limit this display.
- -b
- List only the broadcast interfaces.
- -C
- List all of the interface cloners available on the system, with no additional information.
This option is mutually exclusive with all other options and commands.
- -d
- List only the interfaces that are down.
- -h
- If you use this option in conjunction with -v,
ifconfig prints the byte statistics are in human-readable format.
- -L
- Display the address lifetime for IPv6 addresses, as a time offset string.
- -l
- List all available interfaces on the system, with no additional information.
This option is mutually exclusive with all other options and commands, except for
-b, -d, -s, -u.
- -m
- Display all of the supported media for all of the interfaces in the
system (used in conjunction with -a).
If you specify the -m option before an interface name,
ifconfig displays all of the supported media for the
specified interface.
- -s
- If you specify the -a option, the -s option
makes ifconfig list only the interfaces that are connected.
If you specify the -s option for a specific interface,
ifconfig queries the interface for its media status.
If the interface supports reporting media status,
and it reports that it doesn't appear to be connected to a network,
ifconfig exits with status of 1 (false);
otherwise, it exits with zero (true).
Not all interface drivers support media status reporting.
- -u
- List only the interfaces that are up.
- -v
- Print statistics on packets sent and received on the given interface.
You can use the -h in conjunction with -v to display
the byte statistics in human-readable format.
- -z
- Similar to the -v flag, except that it zeros the interface's
input and output statistics after printing them.
- interface
- The name of the interface to configure.
This is a string of the form name unit (e.g., en1).
- address
- Either a hostname present in the
/etc/hosts
database,
or a DARPA-Internet address expressed in the standard Internet
“dot notation.”
For the Xerox Network Systems family, addresses are in the form
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, 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 you wish to (carefully)
count out long strings of digits in network byte order.
- address_family
- The address family that affects the interpretation of the remaining parameters.
Specifying an address family is recommended since an interface can receive
transmissions in differing protocols with different naming schemes.
Address or protocol families currently supported are inet,
inet6, atalk, iso, and
ns.
- dest_address
- Address of the correspondent on the other end of a
point-to-point link (for pppx interfaces only).
- parameters
- See the
“Parameters”
section below.
- protocol_family
- Report only the details specific to this protocol family.
Description:
The ifconfig utility is used to assign an address and/or
configure parameters for a network interface. This utility must be run at
boot time to define the
network address of each interface present on a machine; it
may also be run later on to redefine an interface's address
or to configure other interface parameters.
When no optional parameters are specified, ifconfig
displays the current configuration for a
network interface.
If you specify a protocol family, ifconfig
reports only the details specific to that protocol family.
Note:
Only the superuser can modify the configuration of a network interface.
Parameters
You may set the following parameters with the ifconfig utility,
if the driver supports them.
The output from ifconfig for an interface lists the
supported parameters.
- acceptrtadv
- (IPv6 only; QNX Neutrino 6.6 or later) Accept router advertisements.
- -acceptrtadv
- (IPv6 only; QNX Neutrino 6.6 or later) Don't accept router advertisements.
- addfib n
- (QNX Neutrino 6.6 or later) Add a Forwarding Information Base (FIB), also
known as a routing table.
The argument is the FIB number.
- alias
- Establish an additional network address for this interface.
This is useful when someone changes the network address of an interface, or when
you want to accept packets addressed to the old interface.
- -alias
- Remove the additional network address for this interface.
- aliasif iface in|out|all
- Configure the alias interface:
- If you specify out, make iface the current interface
for outbound packets on the alias pseudo-interface.
- If you specify in, add iface to the list of interfaces
on which inbound packets will be accepted for the alias pseudo-interface.
- If you specify all, iface is both set as the
current output interface and added to the list of input interfaces.
- -aliasif iface in|out|all
- Remove iface as an input or output interface for the alias pseudo-interface,
or both, if you specify all.
- anycast
- (inet6 only) Set the IPv6 anycast address bit.
- -anycast
- (inet6 only) Clear the IPv6 anycast address bit.
- apbridge
- (IEEE 802.11 devices only) When operating as an access point, pass
packets between wireless clients directly (the default).
- -apbridge
- (IEEE 802.11 devices only) When operating as an access point, pass
packets through the system so that they can be forwarded using some
other mechanism.
Disabling the internal bridging is useful when traffic is to be
processed with packet filtering.
- arp
- Enable the use of the Address Resolution Protocol in mapping between network-level
addresses and link-level addresses (default).
This is implemented to do mapping between DARPA Internet addresses and Ethernet addresses.
- -arp
- Disable the use of the Address Resolution Protocol.
- broadcast mask
- (inet only) Use this address to represent broadcasts to the network.
The default broadcast address is the address with a host part of all 1's.
- bssid bssid
- (IEEE 802.11 devices only) Set the desired BSSID for IEEE 802.11-based
wireless network interfaces.
- -bssid
- (IEEE 802.11 devices only) Unset the desired BSSID for
IEEE 802.11-based wireless network interfaces.
The interface will automatically select a BSSID in this mode,
which is the default.
- chan chan
- (IEEE 802.11 devices only) Select the channel (radio
frequency) to use for IEEE 802.11-based wireless network interfaces.
- -chan
- (IEEE 802.11 devices only) Unset the desired channel
to be used for IEEE 802.11-based wireless network interfaces.
It doesn't affect the channel to be created for IBSS or hostap mode.
- chanlist channels
- Set the channels to use when scanning for access points,
neighbors in an IBSS network, or looking for unoccupied channels
when operating as an access point.
Specify the set of channels as a comma-seperated list, with each element
in the list representing either a single channel number of a range of
the form a-b.
Channel numbers must be in the range 1 through 255 and be
permissible according to the operating characteristics of the device.
- create
- Create the specified network pseudo-device.
- debug
- Enable driver-dependent debugging code; usually, this
turns on extra console error logging.
- -debug
- Disable driver-dependent debugging code.
- delete
- Remove a specified network address. You should use this parameter if you have
incorrectly specified an alias, or you will no longer use an alias. In the event that you have
incorrectly set an NS address which has the side effect of specifying the host portion, you
must respecify the host portion while removing all NS addresses. Note that this parameter
doesn't work for IPv6 addresses.
If you need to delete IPv6 addresses, use -alias with an
explicit IPv6 address.
- deletetunnel
- Unconfigure the physical source and destination address
for IP tunnel interfaces previously configured with tunnel.
- delfib n
- (QNX Neutrino 6.6 or later) Delete the Forwarding Information Base
with the given number.
- deprecated
- (inet6 only) Set the IPv6 deprecated address bit.
- -deprecated
- (inet6 only) Clear the IPv6 deprecated address bit.
- destroy
- Destroy the specified network pseudo-device.
- dest_address
- Specify the address of the correspondent on the other end of a point-to-point link.
- down
- Mark an interface as being down.
When an interface is marked down, the system doesn't
attempt to transmit messages through that interface.
If possible, the interface is reset to disable reception as well.
This action doesn't automatically disable routes using the interface.
- eui64
- (inet6 only) Fill the interface index (the lowermost 64 bits
of an IPv6 address) automatically.
- getfib
- (QNX Neutrino 6.6 or later) Get the number of the current
Forwarding Information Base.
- hidessid
- (IEEE 802.11 devices only) When operating as an access point, don't
broadcast the SSID in beacon frames or respond to probe request frames
unless they're directed to the access point (i.e. they include its SSID).
By default, the SSID is included in beacon frames, and undirected
probe request frames are answered.
- -hidessid
- (IEEE 802.11 devices only) When operating as an access
point, broadcast the SSID in beacon frames and answer and
respond to undirected probe request frames (default).
- instance minst
- Set the media instance to minst. This is useful for
devices that have multiple physical layer interfaces (PHYs).
Setting the instance on such devices may not be
strictly required by the network interface driver because the
driver may take care of this automatically; see the
driver's documentation for more information.
- ip4csum, ip4csum-rx, ip4csum-tx
- Enable hardware-assisted IPv4 header checksums, if they're supported.
You can restrict this action to either the Rx or Tx direction,
if the hardware permits it.
- -ip4csum, -ip4csum-rx, -ip4csum-tx
- Disable hardware-assisted IPv4 header checksums.
- ipdst
- Specify an Internet host that's 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 is taken as the NS address and network of the destination.
IP encapsulation of CLNP packets is done differently.
- link mac [active|delete]
- Dynamically modify the specified interface's MAC addresses.
If you don't specify active or delete,
ifconfig adds the given MAC address.
The active command activates the address, and the
delete command removes it.
The shim driver doesn't support this feature.
- link[0-2]
- Enable special processing of the link level of the interface.
These three options are interface-specific in actual effect, but
you use them in general to select special modes of operation.
An example of this is to select the connector
type for some ethernet cards.
For more information, see the documentation for the specific driver.
- -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 interfaces support the mutually exclusive use of one of several
different physical media connectors.
For example, a 10 Mb/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 to 10baseT or UTP would activate
twisted pair.
Refer to the interfaces' driver-specific documentation for a
complete list of the available types.
- mediaopt opts
- Set the specified media options on the interface.
The opts argument is a comma-delimited list of options to
apply to the interface.
For information about the available options, see the documentation for
each driver.
- -mediaopt opts
- Disable the specified media options on the interface.
- metric n
- Set the routing metric of the interface to n.
The default is 0.
The routing metric is used by the routing protocol
(routed).
Higher metrics have the effect of making a
route less favorable; metrics are counted as additional
hops to the destination network or host.
- mode mode
- If the driver supports the media selection system, set
the specified operating mode on the interface to mode.
For IEEE 802.11 wireless interfaces that support multiple
operating modes, this directive is used to select between
802.11a (11a), 802.11b (11b), and 802.11g
(11g) operating modes.
- mtu n
- Set the maximum transmission unit of the interface to n.
Most interfaces don't support this parameter.
- name new_name
- Change the name of the interface to new_name.
- netmask mask
- (inet, inet6, and ISO) 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.
You can specify the mask as a single
hexadecimal number with a leading 0x, with a dot-notation
Internet address, or with a pseudo-network name listed in the network
table, networks.
The mask contains ones for the bit positions in the 32-bit address that
are to be used for the network and subnet parts, and zeroes 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.
For INET and INET6 addresses, you can also give the netmask 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 remaining 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's
really the NSAP that's 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 different from 1 may be useful
for AFI 37 type addresses.
- nwid id
- A synonym for ssid.
- 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 preceded by 0x, or a set of keys in the form
n:k1,k2,k3,k4, where n specifies which of keys will be
used for all transmitted packets, and four keys, k1
through k4, are configured as WEP keys.
Note that the order must be matched within same network if you use
multiple keys.
For IEEE 802.11 wireless network, the length of each key is restricted to 40 bits, i.e., a 5-character
string or 10 hexadecimal digits, 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 persistent key written in the
network card.
- nwkey persist:key
- (IEEE 802.11 devices only) Write the key to the persistent memory
of the network card, and enable WEP encryption 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.
- pltime n
- (inet6 only) Set the preferred lifetime for the address, in seconds.
- 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 duration,
in milliseconds, for the 802.11 power-saving mode.
- prefixlen n
- (inet and inet6 only) Similar to netmask,
but you can specify the length of the prefix.
- setfib n
- (QNX Neutrino 6.6 or later) Set the Forwarding Information Base (FIB)
to be the one with the given number.
- ssid id
- (IEEE 802.11 devices only) Configure the Service Set Identifier
(also known as the network name) for IEEE 802.11-based wireless
network interfaces.
The id can either be any text string up to 32 characters
in length, or a series of up to 64 hexadecimal digits preceded by
0x.
Setting id to the empty string allows the interface to connect
to any available access point.
- tcp4csum, tcp4csum-rx, tcp4csum-tx
- Enable hardware-assisted TCP/IPv4 checksums, if they're supported.
You can restrict this action to either the Rx or Tx direction,
if the hardware permits it.
- -tcp4csum, -tcp4csum-rx, -tcp4csum-tx
- Disable hardware-assisted TCP/IPv4 checksums.
- tcp6csum, tcp6csum-rx, tcp6csum-tx
- Enable hardware-assisted TCP/IPv6 checksums, if they're supported.
You can restrict this action to either the Rx or Tx direction,
if the hardware permits it.
- -tcp6csum, -tcp6csum-rx, -tcp6csum-tx
- Disable hardware-assisted TCP/IPv6 checksums.
- tentative
- (inet6 only) Set the IPv6 tentative address bit.
- -tentative
- (inet6 only) Clear the IPv6 tentative address bit.
- tso4
- Enable hardware-assisted TCP/IPv4 segmentation on interfaces that support it.
- -tso4
- Disable hardware-assisted TCP/IPv4 segmentation on interfaces that support it.
- tunnel src_addr[,src_port]
dest_addr[,dest_port]
- (IP tunnel devices only)
Configure the physical source and destination address for
IP tunnel interfaces, including
gif.
The arguments, src_addr and dest_addr are
interpreted as the outer source and destination for the encapsulating
IPv4/IPv6 header.
On a
gre
interface in UDP mode, the arguments src_port
and dest_port are interpreted as the outer source and
destination port for the encapsulating UDP header.
- udp4csum, udp4csum-rx, udp4csum-tx
- Enable hardware-assisted UDP4 checksums, if they're supported.
You can restrict this action to either the Rx or Tx direction,
if the hardware permits it.
- -udp4csum, -udp4csum-rx, -udp4csum-tx
- Disable hardware-assisted UDP4 checksums.
- udp6csum, udp6csum-rx, udp6csum-tx
- Enable hardware-assisted UDP6 checksums, if they're supported.
You can restrict this action to either the Rx or Tx direction,
if the hardware permits it.
- -udp6csum, -udp6csum-rx, -udp6csum-tx
- Disable hardware-assisted UDP6 checksums.
- up
- Mark an interface as being up.
You can use this to enable an interface after an
ifconfig down command.
By default, an interface is
marked as “up” the first time ifconfig
is run to assign the interface an address.
If the interface was reset when previously marked down, the hardware
is reinitialized.
- vlan tag
- If the interface is a
vlan
pseudo-interface, set the
VLAN tag to tag.
This is a 12-bit number which is used to create an 802.1Q VLAN header for packets sent from the
vlan interface.
Note that you must set vlan and vlanif at the same time.
- vlanif iface
- If the interface is a vlan pseudo-interface, associate
the physical 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 physical interface with the correct VLAN
tag will be diverted to the associated vlan pseudo-interface.
The VLAN interface is assigned a copy of the physical interface's flags and Ethernet address.
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 that you must set vlan and vlanif at the same time.
- vlanprio priority
- If the interface is a vlan pseudo-interface, set the
VLAN priority to priority.
This is a number in the range 0–7, used to create an 802.1Q VLAN header
for packets sent from the vlan interface.
- vltime n
- (inet6 only) Set the valid lifetime for the address.
The following parameters are specific to IEEE 802.11 wireless interfaces:
- list active
- Display the list of channels available for use, taking into
account any restrictions set with the chanlist directive.
See the description of list chan for more information.
- list caps
- Display the adaptor's capabilities, including the operating modes supported.
- list chan
- Display the list of channels available for use.
Channels are shown with their IEEE channel number, equivalent frequency, and usage modes.
Channels identified as “11g” are also usable in “11b” mode.
Channels identified as “11a Turbo” may be used only for Atheros' Static Turbo
mode (specified with mediaopt turbo).
Channels marked with a * have a regulatory constraint that they be
passively scanned.
This means a station isn't permitted to transmit on the channel until it identifies the
channel as being used for 802.11 communication, typically by hearing a beacon frame
from an access point operating on the channel.
You can also use list freq to request this information.
- list mac
- Display the current MAC Access Control List state.
Each address is prefixed with a character that indicates the current policy applied to it:
| This character: |
Indicates: |
| + |
The address is allowed access. |
| - |
The address is denied access. |
| * |
The address is present, but the current policy is open (so the ACL isn't consulted). |
- list scan
- Display the access points and/or ad hoc neighbors located in the vicinity.
You can use the -v option to display long SSIDs.
This information may be updated automatically by the adaptor and/or with a scan request.
You can also use list ap to request this information.
- list sta
- When operating as an access point, display the stations that are currently associated.
When operating in ad hoc mode, display stations identified as neighbors in the IBSS.
Capabilities advertised by the stations are described under the scan request.
Depending on the capabilities of the stations, the following flags can be included in the output:
- A
- Authorized. Indicates that the station is permitted to send/receive data frames.
- E
- Extended Rate Phy (ERP).
Indicates that the station is operating in an 802.11g network using extended transmit rates.
- P
- Power Save. Indicates that the station is operating in power-saving mode.
- scan
- Initiate a scan of neighboring stations, wait for it to
complete, and display all stations found.
Only the superuser can initiate a scan.
Depending on the capabilities of the APs, the following flags can be included in the output:
- E
- Extended Service Set (ESS).
Indicates that the station is part of an infrastructure network (in contrast to an
IBSS/ad hoc network).
- I
- IBSS/ad hoc network.
Indicates that the station is part of an ad hoc network (in contrast to an ESS network).
- P
- Privacy. Data confidentiality is required for all data frames exchanged within the BSS.
This means that this BSS requires the station to use
cryptographic means such as WEP, TKIP, or AES-CCMP
to encrypt and decrypt data frames being exchanged with others.
- S
- Short Preamble.
Indicates that the network is using short preambles (defined in 802.11b High Rate/DSSS PHY).
A short preamble uses a 56-bit sync field, in contrast to a 128-bit
field used in long preamble mode.
- s
- The network is using a short slot time.
You can use the list scan request to show recent scan
results without initiating a new scan.
You can use the -v option to prevent the shortening of
long SSIDs.
Diagnostics
Depending on the error, the utility may display messages indicating:
- the specified interface doesn't exist
- the requested address is unknown
- the user isn't privileged and tried to alter an interface's configuration
Examples:
Enable hardware-assisted TCP/IPv6 checksums on an interface:
ifconfig wm0 tcp6csum