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IFCONFIG(8) System Manager's Manual IFCONFIG(8)

ifconfig —
configure network interface parameters

ifconfig [
-AaC
] [
interface
] [
address_family
] [
address [
dest_address
]
] [
parameters
]

The ifconfig utility is used to assign an address to a network interface and/or configure network interface parameters. Generally speaking, hostname.if(5) files are used at boot-time to define the network address of each interface present on a machine; ifconfig is used at a later time to redefine an interface's address or other operating parameters.
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 no parameters are provided, a summary of all interfaces is provided.
Only the superuser may modify the configuration of a network interface.
The following options are available:
 
 
Causes full interface alias information for each interface to be displayed.
 
 
Causes ifconfig to print information on all interfaces. The protocol family may be specified as well. This is the default, if no parameters are given to ifconfig.
 
 
Print the names of all network pseudo-devices that can be created dynamically at runtime using ifconfig create.
 
 
interface
The interface parameter is a string of the form “name unit”, for example, “en0”. If no optional parameters are supplied, this string can instead be just “name”. If an interface group of that name exists, all interfaces in the group will be shown. Otherwise all interfaces of the same type will be displayed (for example, “fxp” will display all fxp(4) interfaces).
 
 
address_family
Specifies the address family which affects interpretation of the remaining parameters. Since an interface can receive transmissions in differing protocols with different naming schemes, specifying the address family is recommended. The address or protocol families currently supported are “inet” and “inet6”.
 
 
address
Internet version 4 and 6 addresses take the form of a host name present in the host name database, hosts(5); “dot” notation (IPv4); colon-separated (IPv6); or CIDR notation.
 
 
dest_address
Specify the address of the correspondent on the other end of a point-to-point link.
The following parameters may be set with ifconfig:
 
 
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.
 
 
A synonym for delete. Use of this option is discouraged in favour of delete.
 
 
Enable the use of the Address Resolution Protocol (ARP) in mapping between network level addresses and link level addresses (default).
 
 
Disable the use of ARP.
 
 
addr
(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.
 
 
Create the specified network pseudo-device. At least the following devices can be created on demand:
bridge(4), carp(4), enc(4), etherip(4), gif(4), gre(4), lo(4), mpe(4), mpw(4), pair(4), pflog(4), pflow(4), pfsync(4), ppp(4), pppoe(4), svlan(4), switch(4), tap(4), trunk(4), tun(4), vether(4), vlan(4), vxlan(4)
 
 
Enable driver-dependent debugging code; usually, this turns on extra console error logging.
 
 
Disable driver-dependent debugging code.
 
 
Remove the default inet address associated with the interface, including any netmask or destination address configured with it. An address and address family can be given to make the deletion more specific.
 
 
value
Specify a description of the interface. This can be used to label interfaces in situations where they may otherwise be difficult to distinguish.
 
 
Clear the interface description.
 
 
Destroy the specified network pseudo-device.
 
 
Mark an interface “down”. When an interface is marked “down”, the system will not attempt to transmit messages through that interface. If possible, the interface will be reset to disable reception as well. This action automatically disables routes using the interface.
 
 
group-name
Assign the interface to a “group”. group-name may not be longer than 15 characters and must not end with a digit. Any interface can be in multiple groups.
For instance, a group could be used to create a hardware independent pf(4) ruleset (i.e. not one based on the names of NICs) using existing (egress, carp, etc.) or user-defined groups.
Some interfaces belong to specific groups by default:
  • All interfaces are members of the all interface group.
  • Cloned interfaces are members of their interface family group. For example, a PPP interface such as ppp0 is a member of the ppp interface family group.
  • pppx(4) interfaces are members of the pppx interface group.
  • The interface(s) the default route(s) point to are members of the egress interface group.
  • IEEE 802.11 wireless interfaces are members of the wlan interface group.
  • Any interfaces used for network booting are members of the netboot interface group.
 
 
group-name
Remove the interface from the given “group”.
 
 
Display the interface hardware features:
CSUM_IPv4
The device supports IPv4 checksum offload.
CSUM_TCPv4
As above, for TCP in IPv4 datagrams.
CSUM_UDPv4
As above, for UDP.
VLAN_MTU
The device can handle full sized frames, plus the size of the vlan(4) tag.
VLAN_HWTAGGING
On transmit, the device can add the vlan(4) tag.
CSUM_TCPv6
As CSUM_TCPv4, but supports IPv6 datagrams.
CSUM_UDPv6
As above, for UDP.
WOL
The device supports Wake on LAN (WoL).
hardmtu
The maximum MTU supported.
 
 
Remove all configured inet(4) addresses on the given interface.
 
 
Disable inet6(4) on the given interface and remove all configured inet6(4) addresses, including the link-local ones. This is the default. To turn inet6 on, use eui64 or autoconf, or assign any inet6 address.
 
 
minst
Set the media instance to minst. This is useful for devices which have multiple physical layer interfaces (PHYs). Setting the instance on such devices may not be strictly required by the network interface driver as the driver may take care of this automatically; see the driver's manual page for more information.
 
 
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 select the connector type for some Ethernet cards. Refer to the man page for the specific driver for more information.
 
 
Disable special processing at the link level with the specified interface.
 
 
etheraddr|random
Change the link layer address (MAC address) of the interface. This should be specified as six colon-separated hex values, or can be chosen randomly.
 
 
prio
Set the priority for link layer communications (arp(4), bpf(4), pppoe(4)).
 
 
[
type
]
Set the media type of the interface to type. If no argument is given, display a list of all available media.
Some interfaces support the mutually exclusive use of one of several different physical media connectors. For example, a 10Mb/s Ethernet interface might support the use of either AUI or twisted pair connectors. Setting the media type to “10base5” or “AUI” would change the currently active connector to the AUI port. Setting it to “10baseT” or “UTP” would activate twisted pair. Refer to the interface's driver-specific man page for a complete list of the available types, or use the following command for a listing of choices:
$ ifconfig interface media
 
 
opts
Set the specified media options on the interface. opts is a comma delimited list of options to apply to the interface. Refer to the interface's driver-specific man page for a complete list of available options, or use the following command for a listing of choices:
$ ifconfig interface media
 
 
opts
Disable the specified media options on the interface.
 
 
nhops
Set the routing metric of the interface to nhops, default 0. The routing metric can be used by routing protocols. Higher metrics have the effect of making a route less favorable.
 
 
mode
If the driver for the interface supports the media selection system, force the mode of the interface to the given mode. For IEEE 802.11 wireless interfaces that support multiple modes, this directive is used to select between 802.11a (“11a”), 802.11b (“11b”), 802.11g (“11g”), and 802.11n (“11n”) modes.
 
 
Select the mode automatically. This is the default for IEEE 802.11 wireless interfaces.
 
 
Enable Multiprotocol Label Switching (MPLS) on the interface, allowing it to send and receive MPLS traffic.
 
 
Disable MPLS on the interface.
 
 
value
Set the MTU for this device to the given value. Cloned routes inherit this value as a default. For Ethernet devices which support setting the MTU, a value greater than 1500 enables jumbo frames. The hardmtu output from hwfeatures shows the maximum supported MTU.
 
 
mask
(inet and inet6 only) Specify how much of the address to reserve for subdividing networks into subnetworks. The mask includes the network part of the local address and the subnet part, which is taken from the host field of the address. The mask can be specified as a single hexadecimal number with a leading 0x, or with a dot-notation Internet address. 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.
 
 
n
(inet and inet6 only) Effect is similar to netmask, but you can specify prefix length by digits.
 
 
n
Set the interface routing priority to n. n is in the range of 0 to 15 with smaller numbers being better. The default priority of an interface is 0, except for IEEE 802.11 wireless interfaces (priority 4) and carp(4) interfaces (priority 15). The default priority of newly connected routes (routes created by configuring an IP address on an interface) is calculated by adding 4 (RTP_CONNECTED) to the interface priority. The default priority of new static routes added to the kernel is calculated by adding 8 (RTP_STATIC) to the interface priority.
 
 
rdomainid
Attach the interface to the routing domain with the specified rdomainid. Interfaces in different routing domains are separated and cannot directly pass traffic between each other. It is therefore possible to reuse the same addresses in different routing domains. If the specified rdomain does not yet exist it will be created, including a routing table with the same id. By default all interfaces belong to routing domain 0.
 
 
Remove the interface from the routing domain and return it to routing domain 0. Any inet and inet6 addresses on the interface will also be removed.
 
 
route-label
(inet) Attach route-label to new network routes of the specified interface. Route labels can be used to implement policy routing; see route(4), route(8), and pf.conf(5).
 
 
Clear the route label.
 
 
If ARP is enabled, the host will only reply to requests for its addresses, and will never send any requests.
 
 
If ARP is enabled, the host will perform normally, sending out requests and listening for replies.
 
 
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.
 
 
Enable Wake on LAN (WoL). When enabled, reception of a WoL frame will cause the network card to power up the system from standby or suspend mode. WoL frames are sent using arp(8).
 
 
Disable WoL. WoL is disabled at boot by the driver, if possible.

The following options are available for a bridge(4) interface:
 
 
interface
Add 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. An interface can be a member of at most one bridge.
 
 
Display the addresses that have been learned by the bridge.
 
 
interface
Add interface as a span port on the bridge.
 
 
interface
Automatically detect the spanning tree edge port status on interface. This is the default for interfaces added to the bridge.
 
 
interface
Disable automatic spanning tree edge port detection on interface.
 
 
interface
Automatically detect the point-to-point status on interface by checking the full duplex link status. This is the default for interfaces added to the bridge.
 
 
interface
Disable automatic point-to-point link detection on interface.
 
 
interface
Mark interface so that only IPv4, IPv6, ARP, and Reverse ARP packets are accepted from it or forwarded to it from other bridge member interfaces.
 
 
interface
Allow non-IPv4, IPv6, ARP, or Reverse ARP packets through interface.
 
 
interface
Remove interface from the bridge. Promiscuous mode is turned off for the interface when it is removed from the bridge.
 
 
address
Delete address from the cache.
 
 
interface
Delete interface from the list of span ports of the bridge.
 
 
interface
Mark interface so that packets are sent out of the interface if the destination port of the packet is unknown. If the bridge has no address cache entry for the destination of a packet, meaning that there is no static entry and no dynamically learned entry for the destination, the bridge will forward the packet to all member interfaces that have this flag set. This is the default for interfaces added to the bridge.
 
 
interface
Mark interface so that packets are not sent out of the interface if the destination port of the packet is unknown. Turning this flag off means that the bridge will not send packets out of this interface unless the packet is a broadcast packet, multicast packet, or a packet with a destination address found on the interface's segment. This, in combination with static address cache entries, prevents potentially sensitive packets from being sent on segments that have no need to see the packet.
 
 
Stop the bridge from forwarding packets.
 
 
interface
Set interface as a spanning tree edge port. An edge port is a single connection to the network and cannot create bridge loops. This allows a straight transition to forwarding.
 
 
interface
Disable edge port status on interface.
 
 
Remove all dynamically learned addresses from the cache.
 
 
Remove all addresses from the cache including static addresses.
 
 
interface
Remove all Ethernet MAC filtering rules from interface.
 
 
time
Set the time (in seconds) before an interface begins forwarding packets. Defaults to 15 seconds, minimum of 4, maximum of 30.
 
 
time
Set the time (in seconds) between broadcasting spanning tree protocol configuration packets. Defaults to 2 seconds, minimum of 1, maximum of 2. This option is only supported in STP mode with rapid transitions disabled; see the proto command for setting the protocol version.
 
 
time
Set the transmit hold count, which is the number of spanning tree protocol packets transmitted before being rate limited. Defaults to 6, minimum of 1, maximum of 10.
 
 
interface num
Set the spanning tree path cost of interface to num. Defaults to 55, minimum of 1, maximum of 200000000 in RSTP mode, and maximum of 65535 in STP mode.
 
 
interface
Automatically calculate the spanning tree priority of interface based on the current link speed, interface status, and spanning tree mode. This is the default for interfaces added to the bridge.
 
 
interface num
Set the spanning tree priority of interface to num. Defaults to 128, minimum of 0, maximum of 240.
 
 
interface
Mark interface so that the source address of packets received from the interface are entered into the address cache. This is the default for interfaces added to the bridge.
 
 
interface
Mark interface so that the source address of packets received from interface are not entered into the address cache.
 
 
Setting this flag stops all IP multicast packets from being forwarded by the bridge.
 
 
Clear the link0 flag on the bridge interface.
 
 
Setting this flag stops all non-IP multicast packets from being forwarded by the bridge.
 
 
Clear the link1 flag on the bridge interface.
 
 
Setting this flag causes all packets to be passed on to ipsec(4) for processing, based on the policies established by the administrator using the ipsecctl(8) command and ipsec.conf(5). If appropriate security associations (SAs) exist, they will be used to encrypt or decrypt the packets. Otherwise, any key management daemons such as isakmpd(8) that are running on the bridge will be invoked to establish the necessary SAs. These daemons have to be configured as if they were running on the host whose traffic they are protecting (i.e. they need to have the appropriate authentication and authorization material, such as keys and certificates, to impersonate the protected host(s)).
 
 
Clear the link2 flag on the bridge interface.
 
 
size
Set the address cache size to size. The default is 100 entries.
 
 
time
Set the time (in seconds) that a spanning tree protocol configuration is valid. Defaults to 20 seconds, minimum of 6, maximum of 40.
 
 
interface ids
Put interface in protected domains. ids is a comma delimited list of domain IDs, between 1 and 31, to put the interface in. Interfaces that are part of a protected domain cannot forward traffic to any other interface in that domain. Interfaces do not belong to any protected domain by default.
 
 
interface
Remove interface from all protected domains.
 
 
value
Force the spanning tree protocol version. The available values are rstp to operate in the default Rapid Spanning Tree (RSTP) mode or stp to force operation in Spanning Tree (STP) mode with rapid transitions disabled.
 
 
interface
Set interface as a point-to-point link. This is required for straight transitions to forwarding and should be enabled for a full duplex link or a trunk(4) with at least two physical links to the same network segment.
 
 
interface
Disable point-to-point link status on interface. This should be disabled for a half duplex link and for an interface connected to a shared network segment, like a hub or a wireless network.
 
 
block|pass [
in | out
] on interface [
src lladdr
] [
dst lladdr
] [
tag tagname
] [
arp | rarp [
request | reply
] [
sha lladdr
] [
spa ipaddr
] [
tha lladdr
] [
tpa ipaddr
]
]
Add a filtering rule to an interface. Rules have a similar syntax to those in pf.conf(5). Rules can be used to selectively block or pass frames based on Ethernet MAC addresses or to tag packets for pf(4) to filter on.
arp(4) packets can be matched with the arp keyword for regular packets and rarp for reverse arp. request and reply limit matches to requests or replies. The source and target host addresses can be matched with the sha and tha keywords, and the protocol addresses with spa and tpa.
Rules are processed in the order in which they were added to the interface. The first rule matched takes the action (block or pass) and, if given, the tag of the rule. If no source or destination address is specified, the rule will match all frames (good for creating a catchall policy).
 
 
filename
Load a set of rules from the file filename.
 
 
interface
Display the active filtering rules in use on interface.
 
 
num
Set the spanning priority of this bridge to num. Defaults to 32768, minimum of 0, maximum of 61440.
 
 
interface address
Add a static entry into the address cache pointing to interface. Static entries are never aged out of the cache or replaced, even if the address is seen on a different interface.
 
 
interface
Enable spanning tree protocol on interface.
 
 
interface
Disable spanning tree protocol on interface. This is the default for interfaces added to the bridge.
 
 
time
Set the timeout, in seconds, for addresses in the cache to time. The default is 240 seconds. If time is set to zero, then entries will not be expired.
 
 
Start the bridge forwarding packets.

ifconfig carp-interface [
advbase n
] [
advskew n
] [
balancing mode
] [
carpnodes vhid:advskew,vhid:advskew,...
] [
carpdev iface
] [
[
-
]carppeer peer_address
] [
pass passphrase
] [
state state
] [
vhid host-id
]
The following options are available for a carp(4) interface:
 
 
n
Set the base advertisement interval to n seconds. Acceptable values are 0 to 254; the default value is 1 second.
 
 
n
Skew the advertisement interval by n. Acceptable values are 0 to 254; the default value is 0.
 
 
mode
Set the load balancing mode to mode. Valid modes are ip, ip-stealth, and ip-unicast.
 
 
vhid:advskew,vhid:advskew,...
Create a load balancing group consisting of up to 32 nodes. Each node is specified as a vhid:advskew tuple in a comma-separated list.
 
 
iface
Attach to parent interface iface.
 
 
peer_address
Send the carp advertisements to a specified point-to-point peer or multicast group instead of sending the messages to the default carp multicast group. The peer_address is the IP address of the other host taking part in the carp cluster. With this option, carp(4) traffic can be protected using ipsec(4) and it may be desired in networks that do not allow or have problems with IPv4 multicast traffic.
 
 
Send the advertisements to the default carp multicast group.
 
 
passphrase
Set the authentication key to passphrase. There is no passphrase by default.
 
 
state
Explicitly force the interface to enter this state. Valid states are init, backup, and master.
 
 
n
Set the virtual host ID to n. Acceptable values are 1 to 255.
Taken together, the advbase and advskew indicate how frequently, in seconds, the host will advertise the fact that it considers itself master of the virtual host. The formula is advbase + (advskew / 256). If the master does not advertise within three times this interval, this host will begin advertising as master.

ifconfig wireless-interface [
[
-
]bssid bssid
] [
[
-
]chan [
n
]
] [
[
-
]join id
] [
[
-
]joinlist
] [
[
-
]nwflag flag
] [
[
-
]nwid id
] [
[
-
]nwkey key
] [
[
-
]powersave [
duration
]
] [
scan
] [
[
-
]wpa
] [
wpaakms akm,akm,...
] [
wpaciphers cipher,cipher,...
] [
wpagroupcipher cipher
] [
[
-
]wpakey passphrase | hexkey
] [
wpaprotos proto,proto,...
]
The following options are available for a wireless interface:
 
 
bssid
Set the desired BSSID.
 
 
Unset the desired BSSID. The interface will automatically select a BSSID in this mode, which is the default.
 
 
[
n
]
Set the channel (radio frequency) to n.
With no channel specified, show the list of channels supported by the device.
 
 
Unset the desired channel. It doesn't affect the channel to be created for IBSS or Host AP mode.
 
 
id
Add the network with NWID/ESSID id to the list of auto-join networks. Information about such networks is retained, such that configured interfaces can automatically switch to such networks as necessary.
The id can either be any text string up to 32 characters in length, or a series of hexadecimal digits up to 64 digits. Any necessary wpakey or nwkey arguments should be specified on the same line. May not be used with nwid.
 
 
id
Remove the network with NWID id, from the list of auto-join networks.
 
 
Show the list of currently configured auto-join networks.
 
 
Remove all networks in the list of auto-join networks.
 
 
flag
Set specified flag. The flag name can be either ‘hidenwid’ or ‘nobridge’. The ‘hidenwid’ flag will hide the network ID (ESSID) in beacon frames when operating in Host AP mode. It will also prevent responses to probe requests with an unspecified network ID. The ‘nobridge’ flag will disable the direct bridging of frames between associated nodes when operating in Host AP mode. Setting this flag will block and filter direct inter-station communications.
Note that the ‘hidenwid’ and ‘nobridge’ options do not provide any security. The hidden network ID will be sent in clear text by associating stations and can be easily discovered with tools like tcpdump(8) and hostapd(8).
 
 
flag
Remove specified flag.
 
 
id
Connect to the network with NWID id. Unlike auto-join networks, information about the network is not retained. The empty string allows the interface to connect to any available access points. May not be used with join.
 
 
Set the NWID to the empty string to allow the interface to connect to any available access point.
 
 
key
Enable WEP encryption using the specified key. The key can either be a string, a series of hexadecimal digits (preceded by ‘0x’), or a set of keys of the form “n:k1,k2,k3,k4” where ‘n’ specifies which of the keys will be used for transmitted packets, and the four keys, “k1” through “k4”, are configured as WEP keys. If a set of keys is specified, a comma (‘,’) within the key must be escaped with a backslash. Note that if multiple keys are used, their order must be the same within the network.
The length of each key must be either 40 bits for 64-bit encryption (5-character ASCII string or 10 hexadecimal digits) or 104 bits for 128-bit encryption (13-character ASCII string or 26 hexadecimal digits).
 
 
Disable WEP encryption.
 
 
persist
Enable WEP encryption using the persistent key stored in the network card.
 
 
persist:key
Write key to the persistent memory of the network card, and enable WEP encryption using that key.
 
 
[
duration
]
Enable 802.11 power saving mode. Optionally set the receiver sleep duration (in milliseconds).
 
 
Disable 802.11 power saving mode.
 
 
Show the results of an access point scan. In Host AP mode, this will dump the list of known nodes without scanning.
 
 
Enable Wi-Fi Protected Access. WPA is a Wi-Fi Alliance protocol based on the IEEE 802.11i standard. It was designed to enhance the security of wireless networks. Notice that not all drivers support WPA. Check the driver's manual page to know if this option is supported.
 
 
Disable Wi-Fi Protected Access.
 
 
akm,akm,...
Set the comma-separated list of allowed authentication and key management protocols.
The supported values are “psk” and “802.1x”. psk authentication (also known as personal mode) uses a 256-bit pre-shared key. 802.1x authentication (also known as enterprise mode) is used with an external IEEE 802.1X authentication server, such as wpa_supplicant. The default value is “psk”. “psk” can only be used if a pre-shared key is configured using the wpakey option.
 
 
cipher,cipher,...
Set the comma-separated list of allowed pairwise ciphers.
The supported values are “tkip”, “ccmp”, and “usegroup”. usegroup specifies that no pairwise ciphers are supported and that only group keys should be used. The default value is “ccmp”. If multiple pairwise ciphers are specified, the pairwise cipher will be negotiated between the station and the access point at association time. A station will always try to use ccmp over tkip if both ciphers are allowed and supported by the access point. If the selected cipher is not supported by the hardware, software encryption will be used. Check the driver's manual page to know which ciphers are supported in hardware.
 
 
cipher
Set the group cipher used to encrypt broadcast and multicast traffic.
The supported values are “wep40”, “wep104”, “tkip”, and “ccmp”. The default value is “ccmp”. The use of tkip or wep40 or wep104 as the group cipher is discouraged due to weaknesses in TKIP and WEP. The wpagroupcipher option is available in Host AP mode only. A station will always use the group cipher of the BSS.
 
 
passphrase | hexkey
Set the WPA key and enable WPA. The key can be given using either a passphrase or a full length hex key, starting with 0x. If a passphrase is used the nwid or join option must first be specified, since ifconfig will hash the nwid along with the passphrase to create the key.
 
 
Delete the pre-shared WPA key and disable WPA.
 
 
proto,proto,...
Set the comma-separated list of allowed WPA protocol versions.
The supported values are “wpa1” and “wpa2”. wpa1 is based on draft 3 of the IEEE 802.11i standard whereas wpa2 is based on the ratified standard. The default value is “wpa2”. If “wpa1,wpa2” is specified, a station will always use the wpa2 protocol when supported by the access point.

ifconfig interface inet6 [
[
-
]anycast
] [
[
-
]autoconf
] [
[
-
]autoconfprivacy
] [
eui64
] [
pltime n
] [
[
-
]soii
] [
[
-
]tentative
] [
vltime n
]
The following options are available for an ip6(4) interface:
 
 
Set the IPv6 anycast address bit.
 
 
Clear the IPv6 anycast address bit.
 
 
Set the AUTOCONF6 flag on the interface. The address autoconfiguration daemon slaacd(8) automatically configures IPv6 addresses for interfaces with this flag.
 
 
Unset the AUTOCONF6 flag on the interface.
 
 
Enable privacy extensions for stateless IPv6 address autoconfiguration (RFC 4941) on the interface. These extensions are enabled by default. The purpose of these extensions is to prevent tracking of individual devices which connect to the IPv6 internet from different networks using stateless autoconfiguration. The interface identifier often remains constant and provides the lower 64 bits of an autoconfigured IPv6 address, facilitating tracking of individual devices (and hence, potentially, users of these devices) over long periods of time (weeks to months to years). When these extensions are active, random interface identifiers are used for autoconfigured addresses.
Autoconfigured addresses are also made temporary, which means that they will automatically be replaced regularly. Temporary addresses are deprecated after 24 hours. Once a temporary address has been deprecated, a new temporary address will be configured upon reception of a router advertisement indicating that the prefix is still valid. Deprecated addresses will not be used for new connections as long as a non-deprecated address remains available. Temporary addresses become invalid after one week, at which time they will be removed from the interface. Address lifetime extension through router advertisements is ignored for temporary addresses.
 
 
Disable IPv6 autoconf privacy extensions on the interface. Currently configured addresses will not be removed until they become invalid.
 
 
Fill the interface index (the lowermost 64 bits of an IPv6 address) automatically.
 
 
n
Set preferred lifetime for the address, in seconds.
 
 
Enable persistent Semantically Opaque Interface Identifiers (SOIIs), as per RFC 7217, for link local and SLAAC addresses on the interface. The purpose of these identifiers is to make discovery of hosts by scanning a whole prefix more difficult. SOIIs use the whole 64 bits of the host part while SLAAC addresses are formed from MAC addresses which can lower the entropy to 24 bits if the host is running in a virtualization environment or the hardware manufacturer is known. See RFC 8064 for details. SOIIs are enabled by default.
 
 
Disable IPv6 persistent Semantically Opaque Interface Identifiers on the interface. Currently configured addresses will not be removed until they become invalid.
 
 
Set the IPv6 tentative address bit.
 
 
Clear the IPv6 tentative address bit.
 
 
n
Set valid lifetime for the address, in seconds.

ifconfig -g group-name [
[
-
]carpdemote [
number
]
]
The following options are available for interface groups:
 
 
group-name
Specify the group.
 
 
[
number
]
Increase carp(4) demote count for given interface group by number. Acceptable values are 0 to 128. If number is omitted, it is increased by 1. Demote count can be set up to 255.
 
 
[
number
]
Decrease carp(4) demote count for given interface group by number. Acceptable values are 0 to 128. If number is omitted, it is decreased by 1.

ifconfig mpe-interface [
mplslabel mpls-label
]
The following options are available for an mpe(4) interface:
 
 
mpls-label
Set the MPLS label to mpls-label. This value is a 20-bit number which will be used as the MPLS header for packets entering the MPLS domain.

ifconfig mpw-interface [
[
-
]controlword
] [
encap encapsulation
] [
mpwlabel local-label remote-label neighbor dest-address
]
The following options are available for an mpw(4) interface:
 
 
Configure the mpw interface to use control-word.
 
 
Remove control-word configuration from the interface.
 
 
encapsulation
Configures the mpw encapsulation type with value encapsulation which can be ethernet or ethernet-tagged. By default it's assumed to be ethernet mode.
 
 
local-label remote-label
Set mpw local label to local-label and remote label to remote-label. The local-label is a 20-bit number which will be used to create a local label route to the mpw interface and the remote-label is another 20-bit number which will be used to create the output label header.
 
 
dest-address
Sets the destination address where this mpw should output. The dest-address is an IPv4 address that will be used to find the nexthop in the MPLS network.

ifconfig pair-interface [
[
-
]patch interface
]
The following options are available for a pair(4) interface:
 
 
interface
Connect the interface with a second pair(4) interface. Any outgoing packets from the first pair-interface will be received by the second interface, and vice versa. This makes it possible to interconnect two routing domains locally.
 
 
If configured, disconnect the interface pair.

ifconfig pflow-interface [
[
-
]flowdst addr:port
] [
[
-
]flowsrc addr[
:port
]
] [
pflowproto n
]
The following options are available for a pflow(4) interface:
 
 
addr:port
Set the receiver address and the port for pflow(4) packets. Both must be defined to export pflow data. addr is the IP address and port is the port number of the flow collector. Pflow data will be sent to this address/port.
 
 
Unset the receiver address and stop sending pflow data.
 
 
addr[
:port
]
Set the source IP address for pflow packets. addr is the IP address used as sender of the UDP packets and may be used to identify the source of the data on the pflow collector.
 
 
Unset the source address.
 
 
n
Set the protocol version. The default is version 5.

ifconfig pfsync-interface [
[
-
]defer
] [
maxupd n
] [
[
-
]syncdev iface
] [
[
-
]syncpeer peer_address
]
The following options are available for a pfsync(4) interface:
 
 
Defer transmission of the first packet in a state until a peer has acknowledged that the associated state has been inserted. See pfsync(4) for more information.
 
 
Do not defer the first packet in a state. This is the default.
 
 
n
Indicate the maximum number of updates for a single state which can be collapsed into one. This is an 8-bit number; the default value is 128.
 
 
iface
Use the specified interface to send and receive pfsync state synchronisation messages.
 
 
Stop sending pfsync state synchronisation messages over the network.
 
 
peer_address
Make the pfsync link point-to-point rather than using multicast to broadcast the state synchronisation messages. The peer_address is the IP address of the other host taking part in the pfsync cluster. With this option, pfsync(4) traffic can be protected using ipsec(4).
 
 
Broadcast the packets using multicast.

ifconfig pppoe-interface [
authkey key
] [
authname name
] [
authproto proto
] [
[
-
]peerflag flag
] [
peerkey key
] [
peername name
] [
peerproto proto
] [
[
-
]pppoeac access-concentrator
] [
pppoedev parent-interface
] [
[
-
]pppoesvc service
]
pppoe(4) uses the sppp(4) "generic" SPPP framework. Any options not described in the section immediately following are described in the SPPP section, below.
The following options are available for a pppoe(4) interface:
 
 
access-concentrator
Set the name of the access-concentrator.
 
 
Clear a previously set access-concentrator name.
 
 
parent-interface
Set the name of the interface through which packets will be transmitted and received.
 
 
service
Set the service name of the interface.
 
 
Clear a previously set service name.

ifconfig sppp-interface [
authkey key
] [
authname name
] [
authproto proto
] [
[
-
]peerflag flag
] [
peerkey key
] [
peername name
] [
peerproto proto
]
The following options are available for an sppp(4) or pppoe(4) interface:
 
 
key
Set the client key or password for the PPP authentication protocol.
 
 
name
Set the client name for the PPP authentication protocol.
 
 
proto
Set the PPP authentication protocol on the specified interface acting as a client. The protocol name can be either ‘chap’, ‘pap’, or ‘none’. In the latter case, authentication will be turned off.
 
 
flag
Set a specified PPP flag for the remote authenticator. The flag name can be either ‘callin’ or ‘norechallenge’. The ‘callin’ flag will require the remote peer to authenticate only when he's calling in, but not when the peer is called by the local client. This is required for some peers that do not implement the authentication protocols symmetrically. The ‘norechallenge’ flag is only meaningful with the CHAP protocol to not re-challenge once the initial CHAP handshake has been successful. This is used to work around broken peer implementations that can't grok being re-challenged once the connection is up.
 
 
flag
Remove a specified PPP flag for the remote authenticator.
 
 
key
Set the authenticator key or password for the PPP authentication protocol.
 
 
name
Set the authenticator name for the PPP authentication protocol.
 
 
proto
Set the PPP authentication protocol on the specified interface acting as an authenticator. The protocol name can be either ‘chap’, ‘pap’, or ‘none’. In the latter case, authentication will be turned off.

The following options are available for a switch(4) interface:
 
 
interface
Add interface as a member of the switch. The interface is put into promiscuous mode so that it can receive every packet sent on the network. An interface can be a member of at most one switch.
 
 
interface
Add interface as a local port of the switch. Local port is a special port connected with the local system's network stack. Only vether(4) can be used for the interface. Only one interface can be added as a local port.
 
 
id
Configure the datapath ID for the switch. The default value is generated randomly.
 
 
interface
Remove interface from the switch. Promiscuous mode is turned off for the interface when it is removed from the switch.
 
 
number
Set the maximum number of flows per table. The default value is 10000.
 
 
number
Set the maximum number of groups. The default value is 1000.
 
 
interface number
Set the port number for the port named interface. The default value is the interface index of the interface.
 
 
Start the switch processing packets.

ifconfig trunk-interface [
[
-
]trunkport child-iface
] [
trunkproto proto
]
The following options are available for a trunk(4) interface:
 
 
active|passive
Set the LACP trunk mode to either active or passive.
 
 
fast|slow
Set the LACP timeout speed to either fast or slow.
 
 
child-iface
Add child-iface as a trunk port.
 
 
child-iface
Remove the trunk port child-iface.
 
 
proto
Set the trunk protocol. Refer to trunk(4) for a complete list of the available protocols.

ifconfig tunnel-interface [
[
-
]keepalive period count
] [
[
-
]tunnel src_address dest_address
] [
[
-
]tunneldf
] [
[
-
]tunneldomain rtable
] [
tunnelttl ttl
] [
[
-
]vnetflowid
] [
[
-
]vnetid network-id
]
etherip(4), gif(4), gre(4), and vxlan(4) are all tunnel interfaces. The following options are available:
 
 
period count
Enable gre(4) keepalive with a packet sent every period seconds. A second timer is run with a timeout of count * period. If no keepalive response is received during that time, the link is considered down. The minimal usable count is 2 since the round-trip time of keepalive packets needs to be accounted for.
 
 
Disable the gre(4) keepalive mechanism.
 
 
src_address dest_address[
:dest_port
]
Set the source and destination tunnel addresses on a tunnel interface. Packets routed to this interface will be encapsulated in IPv4 or IPv6, depending on the source and destination address families. Both addresses must be of the same family. The optional destination port can be specified for interfaces such as vxlan(4), which further encapsulate the packets in UDP datagrams.
 
 
Remove the source and destination tunnel addresses.
 
 
Do not allow fragmentation of encapsulated packets.
 
 
Allow fragmentation of encapsulated packets.
 
 
rtable
Use routing table rtable instead of the default table. The tunnel does not need to terminate in the same routing domain as the interface itself. rtable can be set to any valid routing table ID; the corresponding routing domain is derived from this table.
 
 
Use the default routing table and routing domain 0.
 
 
ttl
Set the IP or multicast TTL of the tunnel packets. If supported by the tunnel protocol, the value can also be set to copy to have the TTL copied between the encapsulated protocol headers and the tunnel protocol headers.
 
 
Use a portion of the virtual network identifier space for a flow identifier. This allows load balancing of the encapsulated traffic over multiple links.
 
 
Disable the use of a flow identifier in the virtual network identifier.
 
 
network-id
Set the virtual network identifier. This is a number which is used by tunnel protocols such as vxlan(4) to identify packets with a virtual network. The accepted size of the number depends on the individual tunnel protocol; it is a 24-bit number for vxlan(4). If supported by the tunnel protocol, the value can also be set to any to accept packets with arbitrary network identifiers (for example for multipoint-to-multipoint modes).
 
 
Clear the virtual network identifier.

ifconfig umb-interface [
[
-
]apn apn
] [
chgpin oldpin newpin
] [
[
-
]class class,class,...
] [
pin pin
] [
puk puk newpin
] [
[
-
]roaming
]
The following options are available for a umb(4) interface:
 
 
apn
Set the Access Point Name (APN) required by the network provider.
 
 
Clear the current APN.
 
 
oldpin newpin
Permanently change the PIN of the SIM card from the current value oldpin to newpin.
 
 
List all available cell classes.
 
 
class,class,...
Set the preferred cell classes. Apart from those listed by class the following aliases can be used: 4G, 3G, and 2G.
 
 
Clear any cell class preferences.
 
 
Marking the interface as "down" will terminate any existing data connection and deregister with the service provider.
 
 
pin
Enter the PIN required to unlock the SIM card. Most SIM cards will not be able to establish a network association without providing a PIN.
 
 
puk newpin
Sets the PIN of the SIM card to newpin using the PUK puk to validate the request.
 
 
Enable data roaming.
 
 
Disable data roaming.
 
 
As soon as the interface is marked as "up", the umb(4) device will try to establish a data connection with the service provider.

ifconfig vlan-interface [
[
-
]parent parent-interface
] [
[
-
]vnetid vlan-tag
]
The following options are available for vlan(4) and svlan(4) VLAN interfaces:
 
 
parent-interface
Associate the VLAN interface with the interface parent-interface. Packets transmitted on vlan(4) or svlan(4) interfaces will be tagged with 802.1Q or 802.1ad headers respectively and transmitted on the specified parent interface. Packets with 802.1Q or 802.1ad tags received by the parent interface with the specified VLAN tag will be diverted to the associated VLAN interface. Unless a custom Ethernet address is assigned to the VLAN interface, it will inherit a copy of the parent interface's Ethernet address.
 
 
Disassociate from the parent interface. This breaks the link between the VLAN interface and its parent.
 
 
vlan-tag
Set the VLAN tag value to vlan-tag. This value is a 12-bit number which is used in the 802.1Q or 802.1ad headers in packets handled by vlan(4) or svlan(4) interfaces respectively. Valid tag values are from 1 to 4095 inclusive.
 
 
Clear the tag value. Packets on a VLAN interface without a tag set will use a value of 0 in their headers.

Assign the address of 192.168.1.10 with a network mask of 255.255.255.0 to interface fxp0:
# ifconfig fxp0 inet 192.168.1.10 netmask 255.255.255.0
Configure the xl0 interface to use 100baseTX, full duplex:
# ifconfig xl0 media 100baseTX mediaopt full-duplex
Label the em0 interface as an uplink:
# ifconfig em0 description "Uplink to Gigabit Switch 2"
Create the gif1 network interface:
# ifconfig gif1 create
Put the athn0 wireless interface into monitor mode:
# ifconfig athn0 mediaopt monitor

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.

netstat(1), ifmedia(4), inet(4), intro(4), netintro(4), route(4), hostname.if(5), hosts(5), rc(8), slaacd(8), tcpdump(8)

The ifconfig command appeared in 4.2BSD.
September 8, 2018 OpenBSD-current