MirOS Manual: ifconfig(8)

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


     ifconfig - configure network interface parameters


     ifconfig interface [address_family] [address [dest_address]] [parameters]
     ifconfig -A | -Am | -a | -am [address_family]
     ifconfig -C
     ifconfig -l
     ifconfig -m interface [address_family]
     ifconfig interface create
     ifconfig interface destroy
     ifconfig carp-interface vhid host-id
     ifconfig pfsync-interface syncif iface
     ifconfig pppoe-interface [pppoedev parent-interface] [pppoesvc service]
              [pppoeac access-concentrator]
     ifconfig tunnel-interface tunnel src_address dest_address
     ifconfig tunnel-interface deletetunnel
     ifconfig vlan-interface vlan vlan-tag vlandev parent-interface


     The ifconfig utility is used to assign an address to a network interface
     and/or configure network interface parameters. ifconfig must be used at
     boot-time to define the network address of each interface present on a
     machine; it may also be used at a later time to redefine an interface's
     address or other operating parameters. To configure a bridge interface,
     use the brconfig(8) program instead.

     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.

     Only the superuser may modify the configuration of a network interface.

     The options are as follows:

     -A      Causes full interface alias information for each interface to be

     -Am     The same as the -A option, but additionally prints interface
             media information for all interfaces.

     -a      Causes ifconfig to print information on all interfaces. The pro-
             tocol family may be specified as well.

     -am     The same as the -a option, but additionally prints interface
             media information for all interfaces.

     -C      Print the names of all network pseudo-devices that can be created
             dynamically at runtime using ifconfig create.

     -l      Print the names of all network interfaces, except some virtual
             interfaces like pflog, pfsync, enc, irip, separated by spaces.

     -m interface
             Print media information for a given interface.

             For the DARPA Internet family, the address is either a host name
             present in the host name database, hosts(5), or a DARPA Internet
             address expressed in the Internet standard "dot notation".

             Internet version 6 addresses are either a host name present in
             the host name database, hosts(5), or an Internet version 6 ad-
             dress in standard colon separated form, as described in the
             inet(3) manual page.

             For the Xerox Network Systems(tm) and Internetwork Packet Ex-
             change families, addresses are of 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 speci-
             fied in hexadecimal. The host number may be omitted on Ethernet
             interfaces, which use the hardware physical address, and on in-
             terfaces other than the first. AppleTalk (LLAP) addresses are
             specified as "nn.na" ("Network Number.Node Address"). Node ad-
             dresses are divided into two classes: User Node IDs and Server
             Node IDs. 1-127($01-$7F) are for User Node IDs while 128-
             254($80-$FE) are used for Server Node IDs. Node 0($00) is not al-
             lowed (unknown) while Node 255($FF) is reserved for the AppleTalk
             broadcast hardware address (broadcast ID).

             IPX addresses are specified as listed in the ipx(3) manual page.

             Specifies the address family which affects interpretation of the
             remaining parameters. Since an interface can receive transmis-
             sions in differing protocols with different naming schemes,
             specifying the address family is recommended. The address or pro-
             tocol families currently supported are "inet", "inet6", "atalk"
             and "ipx".

             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". In this case, all interfaces
             of that type will be displayed. For example, "carp" will display
             the current configuration of all carp(4) interfaces.

     The following parameters may be set with ifconfig:

     802.2 802.2tr 802.3 snap EtherII
                     Set the ipx(3) frame type to be either 802.2, 802.2tr,
                     802.3, snap, or Ethernet II.

     advbase n       If the driver is a carp(4) pseudo-device, set the base
                     advertisement interval to n seconds. This is an 8-bit
                     number; the default value is 1 second.

     advskew n       If the driver is a carp(4) pseudo-device, skew the adver-
                     tisement interval by n. This is an 8-bit number; the de-
                     fault value is 0.

                     Taken together the advbase and advskew indicate how fre-
                     quently, in seconds, the host will advertise the fact
                     that it considers itself master of the virtual host. The
                     formula is advbase + (advskew / 255 ). If the master does
                     not advertise within three times this interval, this host
                     will begin advertising as master.

     alias           Establish an additional network address for this inter-
                     face. This is sometimes useful when changing network
                     numbers, and one wishes to accept packets addressed to
                     the old interface.

     -alias          Remove the specified network address alias.

     anycast         (inet6 only) Set the IPv6 anycast address bit.

     -anycast        (inet6 only) Clear the IPv6 anycast address bit.

     arp             Enable the use of the Address Resolution Protocol
                     (``ARP''; see arp(4)) in mapping between network level
                     addresses and link level addresses (default). This is
                     currently implemented for mapping between DARPA Internet
                     addresses and Ethernet addresses.

     -arp            Disable the use of ARP.

     broadcast 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          Create the specified network pseudo-device. At least the
                     following devices can be created on demand:

                     bridge(4), carp(4), gif(4), gre(4), lo(4), ppp(4),
                     pppoe(4), sl(4), tun(4), vlan(4)

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

     -debug          Disable driver-dependent debugging code.

     delete          Remove the network address specified. This would be used
                     if you incorrectly specified an alias, or it was no
                     longer needed.

     deletetunnel    Removes the source and destination tunnel addresses, con-
                     figured onto a tunnel interface.

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

     destroy         Destroy the specified network pseudo-device.

     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 au-
                     tomatically disables routes using the interface.

     eui64           (inet6 only) Fill the interface index (the lowermost 64th
                     bit of an IPv6 address) automatically.

     instance minst  Set the media instance to minst. This is useful for dev-
                     ices 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.

     link[0-2]       Enable special processing of the link level of the inter-
                     face. These three options are interface specific in actu-
                     al effect; however, they are in general used to select
                     special modes of operation. An example of this is to en-
                     able SLIP compression, or to select the connector type
                     for some Ethernet cards. Refer to the man page for the
                     specific driver for more information.

     -link[0-2]      Disable special processing at the link level with the
                     specified interface.

     maxupd n        If the driver is a pfsync(4) pseudo-device, 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.

     media type      Set the media type of the interface to type. Some inter-
                     faces 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 ei-
                     ther AUI or twisted pair connectors. Setting the media
                     type to "10base5" or "AUI" would change the currently ac-
                     tive connector to the AUI port. Setting it to "10baseT"
                     or "UTP" would activate twisted pair. Refer to the
                     interface's driver-specific man page for a complete list
                     of the available types, or use

                           $ ifconfig -m interface

                     for a listing of choices.

     mediaopt opts   Set the specified media options on the interface. opts is
                     a comma delimited list of options to apply to the inter-
                     face. Refer to the interface's driver-specific man page
                     for a complete list of available options, or use

                           $ ifconfig -m interface

                     for a listing of choices.

     -mediaopt opts  Disable the specified media options on the interface.

     metric nhops    Set the routing metric of the interface to nhops, default
                     0. The routing metric is used by the routing protocol
                     (see 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 value       Set the MTU for this device to the given value. Cloned
                     routes will inherit this value as a default. Currently,
                     not all devices support setting the MTU.

     netmask mask    (inet, inet6) Specify how much of the address to reserve
                     for subdividing networks into subnetworks. The mask in-
                     cludes the network part of the local address and the sub-
                     net part, which is taken from the host field of the ad-
                     dress. 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 net-
                     work 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.

     nwkey key       (IEEE 802.11 devices only) Enable WEP encryption for IEEE
                     802.11-based wireless network interfaces using the speci-
                     fied 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 multi-
                     ple keys are used, their order must be the same within
                     the network. For IEEE 802.11 wireless networks, the
                     length of each key is restricted to 40 bits, i.e. a 5-
                     character string or 10 hexadecimal digits. WaveLAN/IEEE
                     Gold and newer Prism cards will also accept a 104-bit
                     (13-character) key.

     -nwkey          (IEEE 802.11 devices only) Disable WEP encryption for
                     IEEE 802.11-based wireless network interfaces.

     nwkey persist   (IEEE 802.11 devices only) Enable WEP encryption for IEEE
                     802.11-based wireless network interfaces with the per-
                     sistent key stored in the network card.

     nwkey persist:key
                     (IEEE 802.11 devices only) Write key to the persistent
                     memory of the network card, and enable WEP encryption for
                     IEEE 802.11-based wireless network interfaces using that

     pass passphrase
                     If the driver is a carp(4) pseudo-device, set the authen-
                     tication key to passphrase. There is no passphrase by de-

     phase n         The argument n specifies the version (phase) of the Ap-
                     pleTalk network attached to the interface. Values of 1 or
                     2 are permitted.

     pltime n        (inet6 only) Set preferred lifetime for the address.

     powersave       (IEEE 802.11 devices only) Enable 802.11 power saving

     -powersave      (IEEE 802.11 devices only) Disable 802.11 power saving

     powersavesleep duration
                     (IEEE 802.11 devices only) Set the receiver sleep dura-
                     tion (in milliseconds) for 802.11 power saving mode.

     pppoeac access-concentrator
                     Set the name of the access-concentrator for the pppoe(4)

     -pppoeac        Clear a previously set access-concentrator name.

     pppoedev parent-interface
                     Set the name of the interface through which pppoe(4)
                     packets will be transmitted and received.

     pppoesvc service
                     Set the service name of the pppoe(4) interface.

     -pppoesvc       Clear a previously set service name.

     prefixlen n     (inet and inet6 only) Effect is similar to netmask, but
                     you can specify prefix length by digits.

     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 OpenBSD implements
                     it internally as a set of netmasks.

     state state     Explicitly force the carp(4) pseudo-device to enter this
                     state. Valid states are init, backup, and master.

     syncif iface    If the driver is a pfsync(4) pseudo-device, use the
                     specified interface to send and receive pfsync state syn-
                     chronisation messages.

     -syncif         If the driver is a pfsync(4) pseudo-device, stop sending
                     pfsync state synchronisation messages over the network.

     tentative       (inet6 only) Set the IPv6 tentative address bit.

     -tentative      (inet6 only) Clear the IPv6 tentative address bit.

     trailers        Request the use of a "trailer" link level encapsulation
                     when sending (default). If a network interface supports
                     trailers, the system will, when possible, encapsulate
                     outgoing messages in a manner which minimizes the number
                     of memory to memory copy operations performed by the re-
                     ceiver. On networks that support ARP (currently, only
                     Ethernet), this flag indicates that the system should re-
                     quest that other systems use trailers when sending to
                     this host. Similarly, trailer encapsulations will be sent
                     to other hosts that have made such requests. Currently
                     used by Internet protocols only.

     -trailers       Disable the use of a "trailer" link level encapsulation.

     tunnel src_address dest_address
                     Set the source and destination tunnel addresses on a tun-
                     nel interface, including gif(4). Packets routed to this
                     interface will be encapsulated in IPv4 or IPv6, depending
                     on the source and destination address families. Both ad-
                     dresses must be of the same family.

     up              Mark an interface "up". This may be used to enable an in-
                     terface 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.

     vhid n          If the driver is a carp(4) pseudo-device, set the virtual
                     host ID to n. Acceptable values are 1 to 255.

     vlan vlan_tag   If the interface is a vlan(4) pseudo-interface, set the
                     vlan tag value to vlan_tag. This value is a 12-bit number
                     which is used to create an 802.1Q vlan header for packets
                     sent from the vlan interface. Note that vlan and vlandev
                     must both be set at the same time.

     vlandev iface   If the interface is a vlan(4) pseudo-device, associate
                     physical interface iface with it. Packets transmitted
                     through the vlan interface will be diverted to the speci-
                     fied physical interface iface with 802.1Q vlan encapsula-
                     tion. Packets with 802.1Q encapsulation received by the
                     parent interface with the correct vlan tag will be
                     diverted to the associated vlan pseudo-interface. The
                     vlan interface is assigned a copy of the parent
                     interface's flags and the parent's Ethernet address.
                     vlandev and vlan must both be set at the same time. If
                     the vlan interface already has a physical interface asso-
                     ciated with it, this command will fail. To change the as-
                     sociation to another physical interface, the existing as-
                     sociation must be cleared first.

                     Note: if the link0 flag is set on the vlan interface, the
                     vlan pseudo-interface's behavior changes; link0 tells the
                     vlan interface that the parent interface supports inser-
                     tion and extraction of vlan tags on its own (usually in
                     firmware) and that it should pass packets to and from the
                     parent unaltered.

     -vlandev        If the driver is a vlan(4) pseudo-device, disassociate
                     the physical interface from it. This breaks the link
                     between the vlan interface and its parent, clears its
                     vlan tag, flags, and link address, and shuts the inter-
                     face down.

     vltime n        (inet6 only) Set valid lifetime for the address.


     Assign the inet(3) address of with a network mask of to interface fxp0:

           # ifconfig fxp0 inet netmask

     Assign the ipx(3) address of 12625920 specified in decimal to interface

           # ifconfig fxp0 ipx 12625920

     Assign the AppleTalk network 39108 and server node 128 with a network
     range of 39107-39109 to interface fxp0 on a phase 2 AppleTalk network:

           # ifconfig fxp0 atalk 39108.128 range 39107-39109 phase 2

     Configure the xl0 interface to use 10baseT:

           # ifconfig xl0 media 10baseT

     Configure the xl0 interface to use 100baseTX, full duplex:

           # ifconfig xl0 media 100baseTX mediaopt full-duplex

     Configure the vlan0 interface for IP address, vlan tag 4,
     and vlan parent device fxp0:

           # ifconfig vlan0 vlan 4 vlandev fxp0

     Configure the carp0 interface for IP address, virtual host
     ID 1:

           # ifconfig carp0 vhid 1

     Create the gif1 network interface:

           # ifconfig gif1 create

     Destroy the gif1 network interface:

           # ifconfig gif1 destroy


     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), inet(3), ipx(3), arp(4), bridge(4), carp(4), gif(4), gre(4),
     ifmedia(4), inet(4), lo(4), netintro(4), pfsync(4), ppp(4), pppoe(4),
     sl(4), tun(4), vlan(4), hostname.if(5), hosts(5), networks(5),
     brconfig(8), rc(8), routed(8)


     The ifconfig command appeared in 4.2BSD.

MirOS BSD #10-current         September 3, 1998                              6

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