IFCONFIG(8)

NAME
ifconfig - configure network interface parameters

SYNOPSIS
ifconfig [-L] [-k] [-m] interface [create] [address_family] [ address [dest_address]] [parameters]
ifconfig interface destroy
ifconfig -a [-L] [-d] [-m] [-u] [-v] [address_family]
ifconfig -l [-d] [-u] [address_family]
ifconfig [-L] [-d] [-k] [-m] [-u] [-v] [-C]

DESCRIPTION
The ifconfig utility is used to assign an address to a network interface and/or configure network interface parameters. The ifconfig 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.

The following options are available:

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”.

    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 192.168.0.1/16.

    For “inet6” family, it is also possible to specify the prefix length using the slash notation, like ::1/128. See the prefixlen parameter below for more information.

    The link-level (“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.

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 “inet”, “inet6”, “atalk”, “ipx”, and “link”. The default is “inet”. “ether” and “lladdr” are synonyms for “link”.

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

interface
    This parameter is a string of the form “name unit”, for example, “ed0”.

The following parameters may be set with ifconfig:

add Another name for the alias parameter. Introduced for compatibility with BSD/OS.

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 0xffffffff is most appropriate.

-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.

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.

arp Enable the use of the Address Resolution Protocol (arp(4)) in mapping between network level addresses and link level addresses (default). This is currently implemented for mapping between DARPA Internet addresses and IEEE 802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses).

-arp
    Disable the use of the Address Resolution Protocol (arp(4)).

staticarp
    If the Address Resolution Protocol is enabled, the host will only reply to requests for its addresses, and will never send any requests.

-staticarp
    If the Address Resolution Protocol is enabled, the host will perform normally, sending out requests and listening for replies.

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.

debug
    Enable driver dependent debugging code; usually, this turns on extra console error logging.

-debug
    Disable driver dependent debugging code.

promisc
    Put interface into permanently promiscuous mode.

-promisc
    Disable permanently promiscuous mode.

delete
    Another name for the -alias parameter.

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 does not automatically disable routes using the interface.

eui64
    (Inet6 only.) Fill interface index (lowermost 64bit of an IPv6 address) automatically.

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.

maclabel label
    If Mandatory Access Control support is enabled in the kernel, set the MAC label to label.

media type
    If the driver supports the media selection system, 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 10Mbit/s Ethernet interface might support the use of either AUI or twisted pair connectors. Setting the media type to 10base5/AUI would change the currently active connector to the AUI port. Setting it to 10baseT/UTP would activate twisted pair. Refer to the interfaces' driver specific documentation or man page for a complete list of the available types.

mediaopt opts
    If the driver supports the media selection system, set the specified media options on the interface. The 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.

-mediaopt opts
    If the driver supports the media selection system, disable the specified media options on the interface.

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.

name name
    Set the interface name to name.

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.

-rxcsum, -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.

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 vlan(4), not on a vlan(4) interface itself.

-vlanmtu, -vlanhwtag
    If the driver offers user-configurable VLAN support, disable reception of extended frames or tag processing in hardware, respectively.

polling
    Turn on polling(4) feature and disable interrupts on the interface, if driver supports this mode.

-polling
    Turn off polling(4) feature and enable interrupt mode on the interface.

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 ifconfig invocation.

destroy
    Destroy the specified network pseudo-device.

plumb
    Another name for the create parameter. Included for Solaris compatibility.

unplumb
    Another name for the destroy parameter. Included for Solaris compatibility.

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, 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.

netmask mask
    (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 ‘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 contiguous with the network portion.

    The netmask can also be specified in CIDR notation after the address. See the address option above for more information.

prefixlen len
    (Inet6 only.) Specify that len bits are reserved for subdividing networks into sub-networks. The 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.

    The prefix can also be specified using the slash notation after the address. See the address option above for more information.

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 FreeBSD implements it internally as a set of netmasks.

remove
    Another name for the -alias parameter. Introduced for compatibility with BSD/OS.

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

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.

monitor
    Put the interface in monitor mode. No packets are transmitted, and received packets are discarded after bpf(4) processing.

-monitor
    Take the interface out of monitor mode.

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.

The following parameters are specific to IEEE 802.11 wireless interfaces:

apbridge
    When operating as an access point, pass packets between wireless clients directly (default). To instead let them pass up through the system and be forwarded using some other mechanism, use -apbridge. Disabling the internal bridging is useful when traffic is to be processed with packet filtering.

authmode mode
    Set the desired authentication mode in infrastructure mode. Not all adaptors support all modes. The set of valid modes is none, open, shared (shared key), 8021x (IEEE 802.1x), and wpa (IEEE WPA/WPA2/802.11i). The 8021x and wpa modes are only useful when using an authentication service (a supplicant for client operation or an authenticator when operating as an access point). Modes are case insensitive.

bintval interval
    Set the interval at which beacon frames are sent when operating in ad-hoc or ap mode. The interval parameter is specified in TU's (1/1024 msecs). By default beacon frames are transmitted every 100 TU's.

bmissthreshold count
    Set the number of consecutive missed beacons at which the station will attempt to roam (i.e. search for a new access point). The count parameter is must be in the range 1 to 255; though the upper bound may be reduced according to device capabilities.. The default threshold is 7 consecutive missed beacons; but this may be overridden by the device driver. Another name for the bmissthreshold parameter is bmiss.

bssid address
    Specify the MAC address of the access point to use when operating as a station in a BSS network. This overrides any automatic selection done by the system. To disable a previously selected access point, supply any, none, or - for the address. This option is useful when more than one access points have the same SSID. Another name for the bssid parameter is ap.

burst
    Enable packet bursting. Packet bursting is a transmission technique whereby the wireless medium is acquired once to send multiple frames and the interframe spacing is reduced. This technique can significantly increase throughput by reducing transmission overhead. Packet bursting is supported by the 802.11e QoS specification and some devices that do not support QoS may still be capable. By default packet bursting is enabled if a device is capable of doing it. To disable packet bursting, use -burst.

chanlist channels
    Set the desired channels to use when scanning for access points, neighbors in an IBSS network, or looking for unoccupied channels when operating as an access point. The set of channels is specified as a comma-separated list with each element in the list representing either a single channel number or a range of the form “a-b”. Channel numbers must be in the range 1 to 255 and be permissible according to the operating characteristics of the device.

channel number
    Set a single desired channel. Channels range from 1 to 255, but the exact selection available depends on the region your adaptor was manufactured for. Setting the channel to 0, any, or - will give you the default for your adaptor. Some adaptors ignore this setting unless you are in ad-hoc mode. Alternatively the frequency, in megahertz, may be specified instead of the channel number.

deftxkey index
    Set the default key to use for transmission. Typically this is only set when using WEP encryption. The weptxkey is an alias for this request; it is provided for backwards compatibility.

dtimperiod period
    Set the DTIM period for transmitting buffered multicast data frames when operating in ap mode. The period specifies the number of beacon intervals between DTIM and must be in the range 1 to 15. By default DTIM is 1 (i.e., DTIM occurs at each beacon).

fragthreshold length
    Set the threshold for which transmitted frames are broken into fragments. The length argument is the frame size in bytes and must be in the range 256 to 2346. Setting length to 2346, any, or - disables transmit fragmentation. Not all adaptors honor the fragmentation threshold.

hidessid
    When operating as an access point, do not broadcast the SSID in beacon frames or respond to probe request frames unless they are directed to the ap (i.e., they include the ap's SSID). By default, the SSID is included in beacon frames and undirected probe request frames are answered. To re-enable the broadcast of the SSID etc., use -hidessid.

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 is not permitted to transmit on the channel until it identifies the channel is being used for 802.11 communication; typically by hearing a beacon frame from an access point operating on the channel. list freq is another way of requesting 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: ‘+’ indicates the address is allowed access, ‘-’ indicates the address is denied access, ‘*’ indicates the address is present but the current policy open (so the ACL is not consulted).

list scan
    Display the access points and/or ad-hoc neighbors located in the vicinity. The -v flag may be used to display long SSIDs. This information may be updated automatically by the adaptor and/or with a scan request. list ap is another way of requesting 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 save mode.

    Q   Quality of Service (QoS). Indicates that the station is using QoS encapsulation for data frame. QoS encapsulation is enabled only when WME mode is enabled.

list wme
    Display the current parameters to use when operating in WME mode. When WME mode is enabled for an adaptor this information will be displayed with the regular status; this command is mostly useful for examining parameters when WME mode is disabled. See the description of the wme directive for information on the various parameters.

mcastrate rate
    Set the rate for transmitting multicast/broadcast frames. Rates are specified as megabits/second in decimal; e.g. 5.5 for 5.5 Mb/s. This rate should be valid for the current operating conditions; if an invalid rate is specified drivers are free to chose an appropriate rate.

powersave
    Enable powersave operation. When operating as a client, the station will conserve power by periodically turning off the radio and listening for messages from the access point telling it there are packets waiting. The station must then retrieve the packets. When operating as an access point, the station must honor power save operation of associated clients. Not all devices support power save operation, either as a client or as an access point. Use -powersave to disable powersave operation.

powersavesleep sleep
    Set the desired max powersave sleep time in milliseconds.

protmode technique
    For interfaces operating in 802.11g, use the specified technique for protecting OFDM frames in a mixed 11b/11g network. The set of valid techniques is off, cts (CTS to self), and rtscts (RTS/CTS). Technique names are case insensitive.

pureg
    When operating as an access point in 802.11g mode allow only 11g-capable stations to associate (11b-only stations are not permitted to associate). To allow both 11g and 11b-only stations to associate, use -pureg.

roaming mode
    When operating as a station, control how the system will behave when communication with the current access point is broken. The mode argument may be one of device (leave it to the hardware device to decide), auto (handle either in the device or the operating system—as appropriate), manual (do nothing until explicitly instructed). By default, the device is left to handle this if it is capable; otherwise, the operating system will automatically attempt to reestablish communication. Manual mode is mostly useful when an application wants to control the selection of an access point.

rtsthreshold length
    Set the threshold for which transmitted frames are preceded by transmission of an RTS control frame. The length argument is the frame size in bytes and must be in the range 1 to 2346. Setting length to 2346, any, or - disables transmission of RTS frames. Not all adaptors support setting the RTS threshold.

ssid ssid
    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 preceded by ‘0x’. Additionally, the SSID may be cleared by setting it to ‘-’.

scan
    Initiate a scan of neighboring stations, wait for it to complete, and display all stations found. Only the super-user 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/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, short preamble utilizes a 56 bit sync field in contrast to a 128 bit field used in long preamble mode).

    s   Short slot time. Indicates that the network is using a short slot time.

    The list scan request can be used to show recent scan results without initiating a new scan.

    The -v flag may be used to prevent the shortening of long SSIDs.

stationname name
    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.

txpower power
    Set the power used to transmit frames. The 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.

wepmode mode
    Set the desired WEP mode. Not all adaptors support all modes. The set of valid modes is off, on, and mixed. The mixed mode explicitly tells the adaptor to allow association with access points which allow both encrypted and unencrypted traffic. On these adaptors, on means that the access point must only allow encrypted connections. On other adaptors, on is generally another name for mixed. Modes are case insensitive.

weptxkey index
    Set the WEP key to be used for transmission. This is the same as setting the default transmission key with deftxkey.

wepkey key|index:key
    Set the selected WEP key. If an 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 preceded by ‘0x’. For maximum portability, hex keys are recommended; the mapping of text keys to WEP encryption is usually driver-specific. In particular, the Windows drivers do this mapping differently to FreeBSD. A key may be cleared by setting it to ‘-’. 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.

wme Enable Wireless Multimedia Extensions (WME) support, if available, for the specified interface. WME is a subset of the IEEE 802.11e standard to support the efficient communication of realtime and multimedia data. To disable WME support, use -wme.

    The following parameters are meaningful only when WME support is in use. Parameters are specified per-AC (Access Category) and split into those that are used by a station when acting as an access point and those for client stations in the BSS. The latter are received from the access point and may not be changed (at the station). The following Access Categories are recognized:

    AC_BE
        (or BE) best effort delivery,
    AC_BK
        (or BK) background traffic,
    AC_VI
        (or VI) video traffic,
    AC_VO
        (or VO) voice traffic.

    AC parameters are case-insensitive. Traffic classification is done in the operating system using the vlan priority associated with data frames or the ToS (Type of Service) indication in IP-encapsulated frames. If neither information is present, traffic is assigned to the Best Effort (BE) category.

    ack ac
        Set the ACK policy for QoS transmissions by the local station; this controls whether or not data frames transmitted by a station require an ACK response from the receiving station. To disable waiting for an ACK use -ack. This parameter is applied only to the local station.

    acm ac
        Enable the Admission Control Mandatory (ACM) mechanism for transmissions by the local station. To disable the ACM use -acm. On stations in a BSS this parameter is read-only and indicates the setting received from the access point. NB: ACM is not supported right now.

    aifs ac count
        Set the Arbitration Inter Frame Spacing (AIFS) channel access parameter to use for transmissions by the local station. On stations in a BSS this parameter is read-only and indicates the setting received from the access point.

    cwmin ac count
        Set the CWmin channel access parameter to use for transmissions by the local station. On stations in a BSS this parameter is read-only and indicates the setting received from the access point.

    cwmax ac count
        Set the CWmax channel access parameter to use for transmissions by the local station. On stations in a BSS this parameter is read-only and indicates the setting received from the access point.

    txoplimit ac limit
        Set the Transmission Opportunity Limit channel access parameter to use for transmissions by the local station. This parameter defines an interval of time when a WME station has the right to initiate transmissions onto the wireless medium. On stations in a BSS this parameter is read-only and indicates the setting received from the access point.

    bss:aifs ac count
        Set the AIFS channel access parameter to send to stations in a BSS. This parameter is meaningful only when operating in ap mode.

    bss:cwmin ac count
        Set the CWmin channel access parameter to send to stations in a BSS. This parameter is meaningful only when operating in ap mode.

    bss:cwmax ac count
        Set the CWmax channel access parameter to send to stations in a BSS. This parameter is meaningful only when operating in ap mode.

    bss:txoplimit ac limit
        Set the TxOpLimit channel access parameter to send to stations in a BSS. This parameter is meaningful only when operating in ap mode.

The following parameters support an optional access control list feature available with some adaptors when operating in ap mode; see wlan_acl(4). This facility allows an access point to accept/deny association requests based on the MAC address of the station. Note that this feature does not significantly enhance security as MAC address spoofing is easy to do.

mac:add address
    Add the specified MAC address to the database. Depending on the policy setting association requests from the specified station will be allowed or denied.

mac:allow
    Set the ACL policy to permit association only by stations registered in the database.

mac:del address
    Delete the specified MAC address from the database.

mac:deny
    Set the ACL policy to deny association only by stations registered in the database.

mac:kick address
    Force the specified station to be deauthenticated. This typically is done to block a station after updating the address database.

mac:open
    Set the ACL policy to allow all stations to associate.

mac:flush
    Delete all entries in the database.

The following parameters are for compatibility with other systems:

nwid ssid
    Another name for the ssid parameter. Included for NetBSD compatibility.

station name
    Another name for the stationname parameter. Included for BSD/OS compatibility.

wep Another way of saying wepmode on. Included for BSD/OS compatibility.

-wep
    Another way of saying wepmode off. Included for BSD/OS compatibility.

nwkey key
    Another way of saying: “wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey 4:-”. Included for NetBSD compatibility.

nwkey
    n:k1,k2,k3,k4 Another way of saying “wepmode on weptxkey n wepkey 1:k1 wepkey 2:k2 wepkey 3:k3 wepkey 4:k4”. Included for NetBSD compatibility.

-nwkey
    Another way of saying wepmode off. Included for NetBSD compatibility.

The following parameters are specific to bridge interfaces:

addm interface
    Add the interface named by interface as a member of the bridge. The interface is put into promiscuous mode so that it can receive every packet sent on the network.

deletem interface
    Remove the interface named by interface from the bridge. Promiscuous mode is disabled on the interface when it is removed from the bridge.

maxaddr size
    Set the size of the bridge address cache to size. The default is 100 entries.

timeout seconds
    Set the timeout of address cache entries to seconds seconds. If seconds is zero, then address cache entries will not be expired. The default is 240 seconds.

addr
    Display the addresses that have been learned by the bridge.

static interface-name address
    Add a static entry into the address cache pointing to interface-name. Static entries are never aged out of the cache or re-placed, even if the address is seen on a different interface.

deladdr address
    Delete address from the address cache.

flush
    Delete all dynamically-learned addresses from the address cache.

flushall
    Delete all addresses, including static addresses, from the address cache.

discover interface
    Mark an interface as a “discovering” interface. When the bridge has no address cache entry (either dynamic or static) for the destination address of a packet, the bridge will forward the packet to all member interfaces marked as “discovering”. This is the default for all interfaces added to a bridge.

-discover interface
    Clear the “discovering” attribute on a member interface. For packets without the “discovering” attribute, the only packets forwarded on the interface are broadcast or multicast packets and packets for which the destination address is known to be on the interface's segment.

learn interface
    Mark an interface as a “learning” interface. When a packet arrives on such an interface, the source address of the packet is entered into the address cache as being a destination address on the interface's segment. This is the default for all interfaces added to a bridge.

-learn interface
    Clear the “learning” attribute on a member interface.

span interface
    Add the interface named by interface as a span port on the bridge. Span ports transmit a copy of every frame received by the bridge. This is most useful for snooping a bridged network passively on another host connected to one of the span ports of the bridge.

-span interface
    Delete the interface named by interface from the list of span ports of the bridge.

stp interface
    Enable Spanning Tree protocol on interface. The if_bridge(4) driver has support for the IEEE 802.1D Spanning Tree protocol (STP). Spanning Tree is used to detect and remove loops in a network topology.

-stp interface
    Disable Spanning Tree protocol on interface. This is the default for all interfaces added to a bridge.

maxage seconds
    Set the time that a Spanning Tree protocol configuration is valid. The default is 20 seconds. The minimum is 1 second and the maximum is 255 seconds.

fwddelay seconds
    Set the time that must pass before an interface begins forwarding packets when Spanning Tree is enabled. The default is 15 seconds. The minimum is 1 second and the maximum is 255 seconds.

hellotime seconds
    Set the time between broadcasting of Spanning Tree protocol configuration messages. The default is 2 seconds. The minimum is 1 second and the maximum is 255 seconds.

priority value
    Set the bridge priority for Spanning Tree. The default is 32768. The minimum is 0 and the maximum is 65536.

ifpriority interface value
    Set the Spanning Tree priority of interface to value. The default is 128. The minimum is 0 and the maximum is 255.

ifpathcost interface value
    Set the Spanning Tree path cost of interface to value. The default is 55. The minimum is 0 and the maximum is 65535.

The following parameters are specific to IP tunnel interfaces, gif(4):

tunnel src_addr dest_addr
    Configure the physical source and destination address for IP tunnel interfaces. The arguments src_addr and dest_addr are interpreted as the outer source/destination for the encapsulating IPv4/IPv6 header.

-tunnel
    Unconfigure the physical source and destination address for IP tunnel interfaces previously configured with tunnel.

deletetunnel
    Another name for the -tunnel parameter.

The following parameters are specific to pfsync(4) interfaces:

maxupd n
    Set 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.

The following parameters are specific to vlan(4) interfaces:

vlan vlan_tag
    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(4) interface. Note that vlan and vlandev must both be set at the same time.

vlandev iface
    Associate the physical interface iface with a vlan(4) interface. Packets transmitted through the vlan(4) 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(4) pseudo-interface. The vlan(4) 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(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.

    Note: if the hardware tagging capability is set on the parent interface, the vlan(4) pseudo interface's behavior changes: the 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.

-vlandev [iface]
    If the driver is a vlan(4) pseudo device, disassociate the parent interface from it. This breaks the link between the vlan(4) interface and its parent, clears its VLAN tag, flags and its link address and shuts the interface down. The iface argument is useless and hence deprecated.

The following parameters are specific to carp(4) interfaces:

advbase seconds
    Specifies the base of the advertisement interval in seconds. The acceptable values are 1 to 255. The default value is 1.

advskew interval
    Specifies the skew to add to the base advertisement interval to make one host advertise slower than another host. It is specified in 1/256 of seconds. The acceptable values are 1 to 254. The default value is 0.

pass phrase
    Set the authentication key to phrase.

vhid n
    Set the virtual host ID. This is a required setting. Acceptable values are 1 to 255.

The ifconfig utility 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 -m flag is passed before an interface name, ifconfig will display the capability list and all of the supported media for the specified interface. If -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. The -d flag limits this to interfaces that are down, and -u limits this to interfaces that are up. When no arguments are given, -a is implied.

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 exclusive with all other flags and commands, except for -d (only list interfaces that are down) and -u (only list interfaces that are up).

The -v flag may be used to get more verbose status for an interface.

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.

The -k flag causes keying information for the interface, if available, to be printed. For example, the values of 802.11 WEP keys will be printed, if accessible to the current user. This information is not printed by default, as it may be considered sensitive.

Only the super-user may modify the configuration of a network interface.

NOTES
The media selection system is relatively new and only some drivers support it (or have need for it).

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), carp(4), netintro(4), pfsync(4), polling(4), vlan(4), rc(8), routed(8), sysctl(8)

HISTORY
The ifconfig utility appeared in 4.2BSD.

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 net.inet6.ip6.auto_linklocal to 0.

If you delete such an address using ifconfig, the kernel may act very oddly. Do this at your own risk.