1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" From: @(#)ifconfig.8 8.3 (Berkeley) 1/5/94 29.\" $FreeBSD: src/sbin/ifconfig/ifconfig.8,v 1.85 2004/07/27 09:51:49 yar Exp $ 30.\" $DragonFly: src/sbin/ifconfig/ifconfig.8,v 1.8 2005/10/13 10:57:50 swildner Exp $ 31.\" 32.Dd July 26, 2004 33.Dt IFCONFIG 8 34.Os 35.Sh NAME 36.Nm ifconfig 37.Nd configure network interface parameters 38.Sh SYNOPSIS 39.Nm 40.Op Fl L 41.Op Fl m 42.Ar interface 43.Op Cm create 44.Op Ar address_family 45.Oo 46.Ar address 47.Op Ar dest_address 48.Oc 49.Op Ar parameters 50.Nm 51.Ar interface 52.Cm destroy 53.Nm 54.Fl a 55.Op Fl L 56.Op Fl d 57.Op Fl m 58.Op Fl u 59.Op Ar address_family 60.Nm 61.Fl l 62.Op Fl d 63.Op Fl u 64.Op Ar address_family 65.Nm 66.Op Fl L 67.Op Fl d 68.Op Fl m 69.Op Fl u 70.Op Fl C 71.Sh DESCRIPTION 72The 73.Nm 74utility is used to assign an address 75to a network interface and/or configure 76network interface parameters. 77The 78.Nm 79utility must be used at boot time to define the network address 80of each interface present on a machine; it may also be used at 81a later time to redefine an interface's address 82or other operating parameters. 83.Pp 84The following options are available: 85.Bl -tag -width indent 86.It Ar address 87For the 88.Tn DARPA Ns -Internet 89family, 90the address is either a host name present in the host name data 91base, 92.Xr hosts 5 , 93or a 94.Tn DARPA 95Internet address expressed in the Internet standard 96.Dq dot notation . 97.Pp 98It is also possible to use the CIDR notation (also known as the 99slash notation) to include the netmask. 100That is, one can specify an address like 101.Li 192.168.0.1/16 . 102.Pp 103For 104.Dq inet6 105family, it is also possible to specify the prefix length using the slash 106notation, like 107.Li ::1/128 . 108See the 109.Cm prefixlen 110parameter below for more information. 111.\" For the Xerox Network Systems(tm) family, 112.\" addresses are 113.\" .Ar net:a.b.c.d.e.f , 114.\" where 115.\" .Ar net 116.\" is the assigned network number (in decimal), 117.\" and each of the six bytes of the host number, 118.\" .Ar a 119.\" through 120.\" .Ar f , 121.\" are specified in hexadecimal. 122.\" The host number may be omitted on IEEE 802 protocol 123.\" (Ethernet, FDDI, and Token Ring) interfaces, 124.\" which use the hardware physical address, 125.\" and on interfaces other than the first. 126.\" For the 127.\" .Tn ISO 128.\" family, addresses are specified as a long hexadecimal string, 129.\" as in the Xerox family. 130.\" However, two consecutive dots imply a zero 131.\" byte, and the dots are optional, if the user wishes to (carefully) 132.\" count out long strings of digits in network byte order. 133.Pp 134The link-level 135.Pq Dq link 136address 137is specified as a series of colon-separated hex digits. 138This can be used to 139e.g.\& set a new MAC address on an ethernet interface, though the 140mechanism used is not ethernet-specific. 141If the interface is already 142up when this option is used, it will be briefly brought down and 143then brought back up again in order to ensure that the receive 144filter in the underlying ethernet hardware is properly reprogrammed. 145.It Ar address_family 146Specify the 147address family 148which affects interpretation of the remaining parameters. 149Since an interface can receive transmissions in differing protocols 150with different naming schemes, specifying the address family is recommended. 151The address or protocol families currently 152supported are 153.Dq inet , 154.Dq inet6 , 155.Dq atalk , 156.Dq ipx , 157.\" .Dq iso , 158and 159.Dq link . 160.\" and 161.\" .Dq ns . 162The default is 163.Dq inet . 164.Dq ether 165and 166.Dq lladdr 167are synonyms for 168.Dq link . 169.It Ar dest_address 170Specify the address of the correspondent on the other end 171of a point to point link. 172.It Ar interface 173This 174parameter is a string of the form 175.Dq name unit , 176for example, 177.Dq Li ed0 . 178.El 179.Pp 180The following parameters may be set with 181.Nm : 182.Bl -tag -width indent 183.It Cm add 184Another name for the 185.Cm alias 186parameter. 187Introduced for compatibility 188with 189.Bsx . 190.It Cm alias 191Establish an additional network address for this interface. 192This is sometimes useful when changing network numbers, and 193one wishes to accept packets addressed to the old interface. 194If the address is on the same subnet as the first network address 195for this interface, a non-conflicting netmask must be given. 196Usually 197.Li 0xffffffff 198is most appropriate. 199.It Fl alias 200Remove the network address specified. 201This would be used if you incorrectly specified an alias, or it 202was no longer needed. 203If you have incorrectly set an NS address having the side effect 204of specifying the host portion, removing all NS addresses will 205allow you to respecify the host portion. 206.It Cm anycast 207(Inet6 only.) 208Specify that the address configured is an anycast address. 209Based on the current specification, 210only routers may configure anycast addresses. 211Anycast address will not be used as source address of any of outgoing 212IPv6 packets. 213.It Cm arp 214Enable the use of the Address Resolution Protocol 215.Pq Xr arp 4 216in mapping 217between network level addresses and link level addresses (default). 218This is currently implemented for mapping between 219.Tn DARPA 220Internet 221addresses and 222.Tn IEEE 223802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses). 224.It Fl arp 225Disable the use of the Address Resolution Protocol 226.Pq Xr arp 4 . 227.It Cm broadcast 228(Inet only.) 229Specify the address to use to represent broadcasts to the 230network. 231The default broadcast address is the address with a host part of all 1's. 232.It Cm debug 233Enable driver dependent debugging code; usually, this turns on 234extra console error logging. 235.It Fl debug 236Disable driver dependent debugging code. 237.It Cm polling 238Enable 239.Xr polling 4 240for the interface. 241.It Fl polling 242Disable 243.Xr polling 4 244for the interface. 245.It Cm promisc 246Put interface into permanently promiscuous mode. 247.It Fl promisc 248Disable permanently promiscuous mode. 249.It Cm delete 250Another name for the 251.Fl alias 252parameter. 253.It Cm down 254Mark an interface 255.Dq down . 256When an interface is marked 257.Dq down , 258the system will not attempt to 259transmit messages through that interface. 260If possible, the interface will be reset to disable reception as well. 261This action does not automatically disable routes using the interface. 262.It Cm eui64 263(Inet6 only.) 264Fill interface index 265(lowermost 64bit of an IPv6 address) 266automatically. 267.\" .It Cm ipdst 268.\" This is used to specify an Internet host who is willing to receive 269.\" ip packets encapsulating NS packets bound for a remote network. 270.\" An apparent point to point link is constructed, and 271.\" the address specified will be taken as the NS address and network 272.\" of the destination. 273.\" IP encapsulation of 274.\" .Tn CLNP 275.\" packets is done differently. 276.It Cm media Ar type 277If the driver supports the media selection system, set the media type 278of the interface to 279.Ar type . 280Some interfaces support the mutually exclusive use of one of several 281different physical media connectors. 282For example, a 10Mb/s Ethernet 283interface might support the use of either 284.Tn AUI 285or twisted pair connectors. 286Setting the media type to 287.Dq Li 10base5/AUI 288would change the currently active connector to the AUI port. 289Setting it to 290.Dq Li 10baseT/UTP 291would activate twisted pair. 292Refer to the interfaces' driver 293specific documentation or man page for a complete list of the 294available types. 295.It Cm mediaopt Ar opts 296If the driver supports the media selection system, set the specified 297media options on the interface. 298The 299.Ar opts 300argument 301is a comma delimited list of options to apply to the interface. 302Refer to the interfaces' driver specific man page for a complete 303list of available options. 304.It Fl mediaopt Ar opts 305If the driver supports the media selection system, disable the 306specified media options on the interface. 307.It Cm mode Ar mode 308If the driver supports the media selection system, set the specified 309operating mode on the interface to 310.Ar mode . 311For IEEE 802.11 wireless interfaces that support multiple operating modes 312this directive is used to select between 802.11a 313.Pq Dq Li 11a , 314802.11b 315.Pq Dq Li 11b , 316and 802.11g 317.Pq Dq Li 11g 318operating modes. 319.It Cm name Ar name 320Set the interface name to 321.Ar name . 322.It Cm rxcsum , txcsum 323If the driver supports user-configurable checksum offloading, 324enable receive (or transmit) checksum offloading on the interface. 325Some drivers may not be able to enable these flags independently 326of each other, so setting one may also set the other. 327The driver will offload as much checksum work as it can reliably 328support, the exact level of offloading varies between drivers. 329.\".It Fl rxcsum , Fl txcsum 330.\"If the driver supports user-configurable checksum offloading, 331.\"disable receive (or transmit) checksum offloading on the interface. 332.\"These settings may not always be independent of each other. 333.\".It Cm polling 334.\"If the driver has user-configurable 335.\".Xr polling 4 336.\"support, select the polling mode on the interface. 337.\".It Fl polling 338.\"If the driver has user-configurable 339.\".Xr polling 4 340.\"support, select the interrupt mode on the interface. 341.It Cm tunnel Ar src_addr dest_addr 342(IP tunnel devices only.) 343Configure the physical source and destination address for IP tunnel 344interfaces 345.Pq Xr gif 4 . 346The arguments 347.Ar src_addr 348and 349.Ar dest_addr 350are interpreted as the outer source/destination for the encapsulating 351IPv4/IPv6 header. 352.It Cm deletetunnel 353Unconfigure the physical source and destination address for IP tunnel 354interfaces previously configured with 355.Cm tunnel . 356.It Cm create 357Create the specified network pseudo-device. 358If the interface is given without a unit number, try to create a new 359device with an arbitrary unit number. 360If creation of an arbitrary device is successful, the new device name is 361printed to standard output. 362.It Cm destroy 363Destroy the specified network pseudo-device. 364.It Cm plumb 365Another name for the 366.Cm create 367parameter. 368Included for 369.Tn Solaris 370compatibility. 371.It Cm unplumb 372Another name for the 373.Cm destroy 374parameter. 375Included for 376.Tn Solaris 377compatibility. 378.It Cm vlan Ar vlan_tag 379If the interface is a 380.Xr vlan 4 381pseudo interface, set the VLAN tag value 382to 383.Ar vlan_tag . 384This value is a 16-bit number which is used to create an 802.1Q 385VLAN header for packets sent from the 386.Xr vlan 4 387interface. 388Note that 389.Cm vlan 390and 391.Cm vlandev 392must both be set at the same time. 393.It Cm vlandev Ar iface 394If the interface is a 395.Xr vlan 4 396pseudo device, associate physical interface 397.Ar iface 398with it. 399Packets transmitted through the 400.Xr vlan 4 401interface will be 402diverted to the specified physical interface 403.Ar iface 404with 802.1Q VLAN encapsulation. 405Packets with 802.1Q encapsulation received 406by the parent interface with the correct VLAN tag will be diverted to 407the associated 408.Xr vlan 4 409pseudo-interface. 410The 411.Xr vlan 4 412interface is assigned a 413copy of the parent interface's flags and the parent's ethernet address. 414The 415.Cm vlandev 416and 417.Cm vlan 418must both be set at the same time. 419If the 420.Xr vlan 4 421interface already has 422a physical interface associated with it, this command will fail. 423To 424change the association to another physical interface, the existing 425association must be cleared first. 426.Pp 427Note: if the hardware tagging capability 428is set on the parent interface, the 429.Xr vlan 4 430pseudo 431interface's behavior changes: 432the 433.Xr vlan 4 434interface recognizes that the 435parent interface supports insertion and extraction of VLAN tags on its 436own (usually in firmware) and that it should pass packets to and from 437the parent unaltered. 438.It Fl vlandev Ar iface 439If the driver is a 440.Xr vlan 4 441pseudo device, disassociate the physical interface 442.Ar iface 443from it. 444This breaks the link between the 445.Xr vlan 4 446interface and its parent, 447clears its VLAN tag, flags and its link address and shuts the interface down. 448.It Cm vlanmtu , vlanhwtag 449If the driver offers user-configurable VLAN support, enable 450reception of extended frames or tag processing in hardware, 451respectively. 452Note that this must be issued on a physical interface associated with 453.Xr vlan 4 , 454not on a 455.Xr vlan 4 456interface itself. 457.It Fl vlanmtu , Fl vlanhwtag 458If the driver offers user-configurable VLAN support, disable 459reception of extended frames or tag processing in hardware, 460respectively. 461.It Cm metric Ar n 462Set the routing metric of the interface to 463.Ar n , 464default 0. 465The routing metric is used by the routing protocol 466.Pq Xr routed 8 . 467Higher metrics have the effect of making a route 468less favorable; metrics are counted as addition hops 469to the destination network or host. 470.It Cm mtu Ar n 471Set the maximum transmission unit of the interface to 472.Ar n , 473default is interface specific. 474The MTU is used to limit the size of packets that are transmitted on an 475interface. 476Not all interfaces support setting the MTU, and some interfaces have 477range restrictions. 478.It Cm netmask Ar mask 479.\" (Inet and ISO.) 480(Inet only.) 481Specify how much of the address to reserve for subdividing 482networks into sub-networks. 483The mask includes the network part of the local address 484and the subnet part, which is taken from the host field of the address. 485The mask can be specified as a single hexadecimal number 486with a leading 487.Ql 0x , 488with a dot-notation Internet address, 489or with a pseudo-network name listed in the network table 490.Xr networks 5 . 491The mask contains 1's for the bit positions in the 32-bit address 492which are to be used for the network and subnet parts, 493and 0's for the host part. 494The mask should contain at least the standard network portion, 495and the subnet field should be contiguous with the network 496portion. 497.Pp 498The netmask can also be specified in CIDR notation after the address. 499See the 500.Ar address 501option above for more information. 502.It Cm prefixlen Ar len 503(Inet6 only.) 504Specify that 505.Ar len 506bits are reserved for subdividing networks into sub-networks. 507The 508.Ar len 509must be integer, and for syntactical reason it must be between 0 to 128. 510It is almost always 64 under the current IPv6 assignment rule. 511If the parameter is omitted, 64 is used. 512.Pp 513The prefix can also be specified using the slash notation after the address. 514See the 515.Ar address 516option above for more information. 517.\" see 518.\" Xr eon 5 . 519.\" .It Cm nsellength Ar n 520.\" .Pf ( Tn ISO 521.\" only) 522.\" This specifies a trailing number of bytes for a received 523.\" .Tn NSAP 524.\" used for local identification, the remaining leading part of which is 525.\" taken to be the 526.\" .Tn NET 527.\" (Network Entity Title). 528.\" The default value is 1, which is conformant to US 529.\" .Tn GOSIP . 530.\" When an ISO address is set in an ifconfig command, 531.\" it is really the 532.\" .Tn NSAP 533.\" which is being specified. 534.\" For example, in 535.\" .Tn US GOSIP , 536.\" 20 hex digits should be 537.\" specified in the 538.\" .Tn ISO NSAP 539.\" to be assigned to the interface. 540.\" There is some evidence that a number different from 1 may be useful 541.\" for 542.\" .Tn AFI 543.\" 37 type addresses. 544.It Cm range Ar netrange 545Under appletalk, set the interface to respond to a 546.Ar netrange 547of the form 548.Ar startnet Ns - Ns Ar endnet . 549Appletalk uses this scheme instead of 550netmasks though 551.Fx 552implements it internally as a set of netmasks. 553.It Cm remove 554Another name for the 555.Fl alias 556parameter. 557Introduced for compatibility 558with 559.Bsx . 560.It Cm phase 561The argument following this specifies the version (phase) of the 562Appletalk network attached to the interface. 563Values of 1 or 2 are permitted. 564.Sm off 565.It Cm link Op Cm 0 No - Cm 2 566.Sm on 567Enable special processing of the link level of the interface. 568These three options are interface specific in actual effect, however, 569they are in general used to select special modes of operation. 570An example 571of this is to enable SLIP compression, or to select the connector type 572for some Ethernet cards. 573Refer to the man page for the specific driver 574for more information. 575.Sm off 576.It Fl link Op Cm 0 No - Cm 2 577.Sm on 578Disable special processing at the link level with the specified interface. 579.\".It Cm monitor 580.\"Put the interface in monitor mode. 581.\"No packets are transmitted, and received packets are discarded after 582.\".Xr bpf 4 583.\"processing. 584.\".It Fl monitor 585.\"Take the interface out of monitor mode. 586.It Cm up 587Mark an interface 588.Dq up . 589This may be used to enable an interface after an 590.Dq Nm Cm down . 591It happens automatically when setting the first address on an interface. 592If the interface was reset when previously marked down, 593the hardware will be re-initialized. 594.It Cm ssid Ar ssid 595For IEEE 802.11 wireless interfaces, set the desired Service Set 596Identifier (aka network name). 597The SSID is a string up to 32 characters 598in length and may be specified as either a normal string or in 599hexadecimal when proceeded by 600.Ql 0x . 601Additionally, the SSID may be cleared by setting it to 602.Ql - . 603.It Cm nwid Ar ssid 604Another name for the 605.Cm ssid 606parameter. 607Included for 608.Nx 609compatibility. 610.It Cm stationname Ar name 611For IEEE 802.11 wireless interfaces, set the name of this station. 612It appears that the station name is not really part of the IEEE 802.11 613protocol though all interfaces seem to support it. 614As such it only 615seems to be meaningful to identical or virtually identical equipment. 616Setting the station name is identical in syntax to setting the SSID. 617.It Cm station Ar name 618Another name for the 619.Cm stationname 620parameter. 621Included for 622.Bsx 623compatibility. 624.It Cm channel Ar number 625For IEEE 802.11 wireless interfaces, set the desired channel. 626Channels range from 1 to 14, but the exact selection available 627depends on the region your adaptor was manufactured for. 628Setting 629the channel to 0 will give you the default for your adaptor. 630Many 631adaptors ignore this setting unless you are in ad-hoc mode. 632.It Cm authmode Ar mode 633For IEEE 802.11 wireless interfaces, set the desired authentication mode 634in infrastructure mode. 635Not all adaptors support all modes. 636The set of 637valid modes is 638.Dq Li none , 639.Dq Li open , 640and 641.Dq Li shared . 642Modes are case insensitive. 643.It Cm powersave 644For IEEE 802.11 wireless interfaces, enable powersave mode. 645.It Fl powersave 646For IEEE 802.11 wireless interfaces, disable powersave mode. 647.It Cm powersavesleep Ar sleep 648For IEEE 802.11 wireless interfaces, set the desired max powersave sleep 649time in milliseconds. 650.It Cm protmode Ar technique 651For IEEE 802.11 wireless interfaces operating in 11g, use the specified 652.Ar technique 653for protecting OFDM frames in a mixed 11b/11g network. 654The set of valid techniques is 655.Dq Li off , 656.Dq Li cts 657(CTS to self), 658and 659.Dq Li rtscts 660(RTS/CTS). 661Technique names are case insensitive. 662.It Cm rtsthreshold Ar length 663For IEEE 802.11 wireless interfaces, set the threshold for which 664transmitted frames are preceded by transmission of an 665RTS 666control frame. 667The 668.Ar length 669argument 670is the frame size in bytes and must be in the range 1 to 2312. 671Not all adaptors support setting the RTS threshold. 672.It Cm txpower Ar power 673For IEEE 802.11 wireless interfaces, set the power used to transmit frames. 674The 675.Ar power 676argument 677is a unitless value in the range 0 to 100 that is interpreted 678by drivers to derive a device-specific value. 679Out of range values are truncated. 680Typically only a few discreet power settings are available and 681the driver will use the setting closest to the specified value. 682Not all adaptors support changing the transmit power. 683.It Cm wepmode Ar mode 684For IEEE 802.11 wireless interfaces, set the desired WEP mode. 685Not all adaptors support all modes. 686The set of valid modes is 687.Dq Li off , 688.Dq Li on , 689and 690.Dq Li mixed . 691The 692.Dq Li mixed 693mode explicitly tells the adaptor to allow association with access 694points which allow both encrypted and unencrypted traffic. 695On these adaptors, 696.Dq Li on 697means that the access point must only allow encrypted connections. 698On other adaptors, 699.Dq Li on 700is generally another name for 701.Dq Li mixed . 702Modes are case insensitive. 703.It Cm weptxkey Ar index 704For IEEE 802.11 wireless interfaces, set the WEP key to be used for 705transmission. 706.It Cm wepkey Ar key Ns | Ns Ar index : Ns Ar key 707For IEEE 802.11 wireless interfaces, set the selected WEP key. 708If an 709.Ar index 710is not given, key 1 is set. 711A WEP key will be either 5 or 13 712characters (40 or 104 bits) depending of the local network and the 713capabilities of the adaptor. 714It may be specified either as a plain 715string or as a string of hexadecimal digits proceeded by 716.Ql 0x . 717For maximum portability, hex keys are recommended; 718the mapping of text keys to WEP encryption is usually driver-specific. 719In particular, the 720.Tn Windows 721drivers do this mapping differently to 722.Fx . 723A key may be cleared by setting it to 724.Ql - . 725If WEP is supported then there are at least four keys. 726Some adaptors support more than four keys. 727If that is the case, then the first four keys 728(1-4) will be the standard temporary keys and any others will be adaptor 729specific keys such as permanent keys stored in NVRAM. 730.It Cm wep 731Another way of saying 732.Cm wepmode on . 733Included for 734.Bsx 735compatibility. 736.It Fl wep 737Another way of saying 738.Cm wepmode off . 739Included for 740.Bsx 741compatibility. 742.It Cm nwkey key 743Another way of saying: 744.Pp 745.Dq Li "wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey 4:-" . 746.Pp 747Included for 748.Nx 749compatibility. 750.It Cm nwkey Xo 751.Sm off 752.Ar n : k1 , k2 , k3 , k4 753.Sm on 754.Xc 755Another way of saying 756.Pp 757.Dq Li "wepmode on weptxkey n wepkey 1:k1 wepkey 2:k2 wepkey 3:k3 wepkey 4:k4" . 758.Pp 759Included for 760.Nx 761compatibility. 762.It Fl nwkey 763Another way of saying 764.Cm wepmode off . 765.Pp 766Included for 767.Nx 768compatibility. 769.El 770.Pp 771The 772.Nm 773utility displays the current configuration for a network interface 774when no optional parameters are supplied. 775If a protocol family is specified, 776.Nm 777will report only the details specific to that protocol family. 778.Pp 779If the driver does supports the media selection system, the supported 780media list will be included in the output. 781.Pp 782If the 783.Fl m 784flag is passed before an interface name, 785.Nm 786will display the capability list and all 787of the supported media for the specified interface. 788If 789.Fl L 790flag is supplied, address lifetime is displayed for IPv6 addresses, 791as time offset string. 792.Pp 793Optionally, the 794.Fl a 795flag may be used instead of an interface name. 796This flag instructs 797.Nm 798to display information about all interfaces in the system. 799The 800.Fl d 801flag limits this to interfaces that are down, and 802.Fl u 803limits this to interfaces that are up. 804When no arguments are given, 805.Fl a 806is implied. 807.Pp 808The 809.Fl l 810flag may be used to list all available interfaces on the system, with 811no other additional information. 812Use of this flag is mutually exclusive 813with all other flags and commands, except for 814.Fl d 815(only list interfaces that are down) 816and 817.Fl u 818(only list interfaces that are up). 819.Pp 820The 821.Fl C 822flag may be used to list all of the interface cloners available on 823the system, with no additional information. 824Use of this flag is mutually exclusive with all other flags and commands. 825.Pp 826Only the super-user may modify the configuration of a network interface. 827.Sh NOTES 828The media selection system is relatively new and only some drivers support 829it (or have need for it). 830.Sh DIAGNOSTICS 831Messages indicating the specified interface does not exist, the 832requested address is unknown, or the user is not privileged and 833tried to alter an interface's configuration. 834.Sh BUGS 835Basic IPv6 node operation requires a link-local address on each 836interface configured for IPv6. 837Normally, such an address is automatically configured by the 838kernel on each interface added to the system; this behaviour may 839be disabled by setting the sysctl MIB variable 840.Va net.inet6.ip6.auto_linklocal 841to 0. 842.Pp 843If you delete such an address using 844.Nm , 845the kernel may act very oddly. 846Do this at your own risk. 847.Sh SEE ALSO 848.Xr netstat 1 , 849.Xr netintro 4 , 850.Xr vlan 4 , 851.\" .Xr eon 5 , 852.Xr rc 8 , 853.Xr routed 8 , 854.Xr sysctl 8 855.Sh HISTORY 856The 857.Nm 858utility appeared in 859.Bx 4.2 . 860