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.\" $FreeBSD$ 30.\" 31.Dd June 14, 2004 32.Dt IFCONFIG 8 33.Os 34.Sh NAME 35.Nm ifconfig 36.Nd configure network interface parameters 37.Sh SYNOPSIS 38.Nm 39.Op Fl L 40.Op Fl m 41.Ar interface 42.Op Cm create 43.Op Ar address_family 44.Oo 45.Ar address 46.Op Ar dest_address 47.Oc 48.Op Ar parameters 49.Nm 50.Ar interface 51.Cm destroy 52.Nm 53.Fl a 54.Op Fl L 55.Op Fl d 56.Op Fl m 57.Op Fl u 58.Op Ar address_family 59.Nm 60.Fl l 61.Op Fl d 62.Op Fl u 63.Op Ar address_family 64.Nm 65.Op Fl L 66.Op Fl d 67.Op Fl m 68.Op Fl u 69.Op Fl C 70.Sh DESCRIPTION 71The 72.Nm 73utility is used to assign an address 74to a network interface and/or configure 75network interface parameters. 76The 77.Nm 78utility must be used at boot time to define the network address 79of each interface present on a machine; it may also be used at 80a later time to redefine an interface's address 81or other operating parameters. 82.Pp 83The following options are available: 84.Bl -tag -width indent 85.It Ar address 86For the 87.Tn DARPA Ns -Internet 88family, 89the address is either a host name present in the host name data 90base, 91.Xr hosts 5 , 92or a 93.Tn DARPA 94Internet address expressed in the Internet standard 95.Dq dot notation . 96.Pp 97It is also possible to use the CIDR notation (also known as the 98slash notation) to include the netmask. 99That is, one can specify an address like 100.Li 192.168.0.1/16 . 101.Pp 102For 103.Dq inet6 104family, it is also possible to specify the prefix length using the slash 105notation, like 106.Li ::1/128 . 107See the 108.Cm prefixlen 109parameter below for more information. 110.\" For the Xerox Network Systems(tm) family, 111.\" addresses are 112.\" .Ar net:a.b.c.d.e.f , 113.\" where 114.\" .Ar net 115.\" is the assigned network number (in decimal), 116.\" and each of the six bytes of the host number, 117.\" .Ar a 118.\" through 119.\" .Ar f , 120.\" are specified in hexadecimal. 121.\" The host number may be omitted on IEEE 802 protocol 122.\" (Ethernet, FDDI, and Token Ring) interfaces, 123.\" which use the hardware physical address, 124.\" and on interfaces other than the first. 125.\" For the 126.\" .Tn ISO 127.\" family, addresses are specified as a long hexadecimal string, 128.\" as in the Xerox family. 129.\" However, two consecutive dots imply a zero 130.\" byte, and the dots are optional, if the user wishes to (carefully) 131.\" count out long strings of digits in network byte order. 132.Pp 133The link-level 134.Pq Dq link 135address 136is specified as a series of colon-separated hex digits. 137This can be used to 138e.g.\& set a new MAC address on an ethernet interface, though the 139mechanism used is not ethernet-specific. 140If the interface is already 141up when this option is used, it will be briefly brought down and 142then brought back up again in order to ensure that the receive 143filter in the underlying ethernet hardware is properly reprogrammed. 144.It Ar address_family 145Specify the 146address family 147which affects interpretation of the remaining parameters. 148Since an interface can receive transmissions in differing protocols 149with different naming schemes, specifying the address family is recommended. 150The address or protocol families currently 151supported are 152.Dq inet , 153.Dq inet6 , 154.Dq atalk , 155.Dq ipx , 156.\" .Dq iso , 157and 158.Dq link . 159.\" and 160.\" .Dq ns . 161The default is 162.Dq inet . 163.Dq ether 164and 165.Dq lladdr 166are synonyms for 167.Dq link . 168.It Ar dest_address 169Specify the address of the correspondent on the other end 170of a point to point link. 171.It Ar interface 172This 173parameter is a string of the form 174.Dq name unit , 175for example, 176.Dq Li ed0 . 177.El 178.Pp 179The following parameters may be set with 180.Nm : 181.Bl -tag -width indent 182.It Cm add 183Another name for the 184.Cm alias 185parameter. 186Introduced for compatibility 187with 188.Bsx . 189.It Cm alias 190Establish an additional network address for this interface. 191This is sometimes useful when changing network numbers, and 192one wishes to accept packets addressed to the old interface. 193If the address is on the same subnet as the first network address 194for this interface, a non-conflicting netmask must be given. 195Usually 196.Li 0xffffffff 197is most appropriate. 198.It Fl alias 199Remove the network address specified. 200This would be used if you incorrectly specified an alias, or it 201was no longer needed. 202If you have incorrectly set an NS address having the side effect 203of specifying the host portion, removing all NS addresses will 204allow you to respecify the host portion. 205.It Cm anycast 206(Inet6 only.) 207Specify that the address configured is an anycast address. 208Based on the current specification, 209only routers may configure anycast addresses. 210Anycast address will not be used as source address of any of outgoing 211IPv6 packets. 212.It Cm arp 213Enable the use of the Address Resolution Protocol 214.Pq Xr arp 4 215in mapping 216between network level addresses and link level addresses (default). 217This is currently implemented for mapping between 218.Tn DARPA 219Internet 220addresses and 221.Tn IEEE 222802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses). 223.It Fl arp 224Disable the use of the Address Resolution Protocol 225.Pq Xr arp 4 . 226.It Cm staticarp 227If the Address Resolution Protocol is enabled, 228the host will only reply to requests for its addresses, 229and will never send any requests. 230.It Fl staticarp 231If the Address Resolution Protocol is enabled, 232the host will perform normally, 233sending out requests and listening for replies. 234.It Cm broadcast 235(Inet only.) 236Specify the address to use to represent broadcasts to the 237network. 238The default broadcast address is the address with a host part of all 1's. 239.It Cm debug 240Enable driver dependent debugging code; usually, this turns on 241extra console error logging. 242.It Fl debug 243Disable driver dependent debugging code. 244.It Cm promisc 245Put interface into permanently promiscuous mode. 246.It Fl promisc 247Disable permanently promiscuous mode. 248.It Cm delete 249Another name for the 250.Fl alias 251parameter. 252.It Cm down 253Mark an interface 254.Dq down . 255When an interface is marked 256.Dq down , 257the system will not attempt to 258transmit messages through that interface. 259If possible, the interface will be reset to disable reception as well. 260This action does not automatically disable routes using the interface. 261.It Cm eui64 262(Inet6 only.) 263Fill interface index 264(lowermost 64bit of an IPv6 address) 265automatically. 266.It Cm ipdst 267This is used to specify an Internet host who is willing to receive 268IP packets encapsulating IPX packets bound for a remote network. 269An apparent point to point link is constructed, and 270the address specified will be taken as the IPX address and network 271of the destination. 272.It Cm maclabel Ar label 273If Mandatory Access Control support is enabled in the kernel, 274set the MAC label to 275.Ar label . 276.\" (see 277.\" .Xr maclabel 7 ) . 278.It Cm media Ar type 279If the driver supports the media selection system, set the media type 280of the interface to 281.Ar type . 282Some interfaces support the mutually exclusive use of one of several 283different physical media connectors. 284For example, a 10Mb/s Ethernet 285interface might support the use of either 286.Tn AUI 287or twisted pair connectors. 288Setting the media type to 289.Dq Li 10base5/AUI 290would change the currently active connector to the AUI port. 291Setting it to 292.Dq Li 10baseT/UTP 293would activate twisted pair. 294Refer to the interfaces' driver 295specific documentation or man page for a complete list of the 296available types. 297.It Cm mediaopt Ar opts 298If the driver supports the media selection system, set the specified 299media options on the interface. 300The 301.Ar opts 302argument 303is a comma delimited list of options to apply to the interface. 304Refer to the interfaces' driver specific man page for a complete 305list of available options. 306.It Fl mediaopt Ar opts 307If the driver supports the media selection system, disable the 308specified media options on the interface. 309.It Cm mode Ar mode 310If the driver supports the media selection system, set the specified 311operating mode on the interface to 312.Ar mode . 313For IEEE 802.11 wireless interfaces that support multiple operating modes 314this directive is used to select between 802.11a 315.Pq Dq Li 11a , 316802.11b 317.Pq Dq Li 11b , 318and 802.11g 319.Pq Dq Li 11g 320operating modes. 321.It Cm name Ar name 322Set the interface name to 323.Ar name . 324.It Cm rxcsum , txcsum 325If the driver supports user-configurable checksum offloading, 326enable receive (or transmit) checksum offloading on the interface. 327Some drivers may not be able to enable these flags independently 328of each other, so setting one may also set the other. 329The driver will offload as much checksum work as it can reliably 330support, the exact level of offloading varies between drivers. 331.It Fl rxcsum , Fl txcsum 332If the driver supports user-configurable checksum offloading, 333disable receive (or transmit) checksum offloading on the interface. 334These settings may not always be independent of each other. 335.It Cm polling 336If the driver has user-configurable 337.Xr polling 4 338support, select the polling mode on the interface. 339.It Fl polling 340If the driver has user-configurable 341.Xr polling 4 342support, select the interrupt mode on the interface. 343.It Cm tunnel Ar src_addr dest_addr 344(IP tunnel devices only.) 345Configure the physical source and destination address for IP tunnel 346interfaces 347.Pq Xr gif 4 . 348The arguments 349.Ar src_addr 350and 351.Ar dest_addr 352are interpreted as the outer source/destination for the encapsulating 353IPv4/IPv6 header. 354.It Cm deletetunnel 355Unconfigure the physical source and destination address for IP tunnel 356interfaces previously configured with 357.Cm tunnel . 358.It Cm create 359Create the specified network pseudo-device. 360If the interface is given without a unit number, try to create a new 361device with an arbitrary unit number. 362If creation of an arbitrary device is successful, the new device name is 363printed to standard output unless the interface is renamed or destroyed 364in the same 365.Nm 366invocation. 367.It Cm destroy 368Destroy the specified network pseudo-device. 369.It Cm plumb 370Another name for the 371.Cm create 372parameter. 373Included for 374.Tn Solaris 375compatibility. 376.It Cm unplumb 377Another name for the 378.Cm destroy 379parameter. 380Included for 381.Tn Solaris 382compatibility. 383.It Cm vlan Ar vlan_tag 384If the interface is a 385.Xr vlan 4 386pseudo interface, set the VLAN tag value 387to 388.Ar vlan_tag . 389This value is a 16-bit number which is used to create an 802.1Q 390VLAN header for packets sent from the 391.Xr vlan 4 392interface. 393Note that 394.Cm vlan 395and 396.Cm vlandev 397must both be set at the same time. 398.It Cm vlandev Ar iface 399If the interface is a 400.Xr vlan 4 401pseudo device, associate physical interface 402.Ar iface 403with it. 404Packets transmitted through the 405.Xr vlan 4 406interface will be 407diverted to the specified physical interface 408.Ar iface 409with 802.1Q VLAN encapsulation. 410Packets with 802.1Q encapsulation received 411by the parent interface with the correct VLAN tag will be diverted to 412the associated 413.Xr vlan 4 414pseudo-interface. 415The 416.Xr vlan 4 417interface is assigned a 418copy of the parent interface's flags and the parent's ethernet address. 419The 420.Cm vlandev 421and 422.Cm vlan 423must both be set at the same time. 424If the 425.Xr vlan 4 426interface already has 427a physical interface associated with it, this command will fail. 428To 429change the association to another physical interface, the existing 430association must be cleared first. 431.Pp 432Note: if the hardware tagging capability 433is set on the parent interface, the 434.Xr vlan 4 435pseudo 436interface's behavior changes: 437the 438.Xr vlan 4 439interface recognizes that the 440parent interface supports insertion and extraction of VLAN tags on its 441own (usually in firmware) and that it should pass packets to and from 442the parent unaltered. 443.It Fl vlandev Ar iface 444If the driver is a 445.Xr vlan 4 446pseudo device, disassociate the physical interface 447.Ar iface 448from it. 449This breaks the link between the 450.Xr vlan 4 451interface and its parent, 452clears its VLAN tag, flags and its link address and shuts the interface down. 453.It Cm metric Ar n 454Set the routing metric of the interface to 455.Ar n , 456default 0. 457The routing metric is used by the routing protocol 458.Pq Xr routed 8 . 459Higher metrics have the effect of making a route 460less favorable; metrics are counted as addition hops 461to the destination network or host. 462.It Cm mtu Ar n 463Set the maximum transmission unit of the interface to 464.Ar n , 465default is interface specific. 466The MTU is used to limit the size of packets that are transmitted on an 467interface. 468Not all interfaces support setting the MTU, and some interfaces have 469range restrictions. 470.It Cm netmask Ar mask 471.\" (Inet and ISO.) 472(Inet only.) 473Specify how much of the address to reserve for subdividing 474networks into sub-networks. 475The mask includes the network part of the local address 476and the subnet part, which is taken from the host field of the address. 477The mask can be specified as a single hexadecimal number 478with a leading 479.Ql 0x , 480with a dot-notation Internet address, 481or with a pseudo-network name listed in the network table 482.Xr networks 5 . 483The mask contains 1's for the bit positions in the 32-bit address 484which are to be used for the network and subnet parts, 485and 0's for the host part. 486The mask should contain at least the standard network portion, 487and the subnet field should be contiguous with the network 488portion. 489.Pp 490The netmask can also be specified in CIDR notation after the address. 491See the 492.Ar address 493option above for more information. 494.It Cm prefixlen Ar len 495(Inet6 only.) 496Specify that 497.Ar len 498bits are reserved for subdividing networks into sub-networks. 499The 500.Ar len 501must be integer, and for syntactical reason it must be between 0 to 128. 502It is almost always 64 under the current IPv6 assignment rule. 503If the parameter is omitted, 64 is used. 504.Pp 505The prefix can also be specified using the slash notation after the address. 506See the 507.Ar address 508option above for more information. 509.\" see 510.\" Xr eon 5 . 511.\" .It Cm nsellength Ar n 512.\" .Pf ( Tn ISO 513.\" only) 514.\" This specifies a trailing number of bytes for a received 515.\" .Tn NSAP 516.\" used for local identification, the remaining leading part of which is 517.\" taken to be the 518.\" .Tn NET 519.\" (Network Entity Title). 520.\" The default value is 1, which is conformant to US 521.\" .Tn GOSIP . 522.\" When an ISO address is set in an ifconfig command, 523.\" it is really the 524.\" .Tn NSAP 525.\" which is being specified. 526.\" For example, in 527.\" .Tn US GOSIP , 528.\" 20 hex digits should be 529.\" specified in the 530.\" .Tn ISO NSAP 531.\" to be assigned to the interface. 532.\" There is some evidence that a number different from 1 may be useful 533.\" for 534.\" .Tn AFI 535.\" 37 type addresses. 536.It Cm range Ar netrange 537Under appletalk, set the interface to respond to a 538.Ar netrange 539of the form 540.Ar startnet Ns - Ns Ar endnet . 541Appletalk uses this scheme instead of 542netmasks though 543.Fx 544implements it internally as a set of netmasks. 545.It Cm remove 546Another name for the 547.Fl alias 548parameter. 549Introduced for compatibility 550with 551.Bsx . 552.It Cm phase 553The argument following this specifies the version (phase) of the 554Appletalk network attached to the interface. 555Values of 1 or 2 are permitted. 556.Sm off 557.It Cm link Op Cm 0 No - Cm 2 558.Sm on 559Enable special processing of the link level of the interface. 560These three options are interface specific in actual effect, however, 561they are in general used to select special modes of operation. 562An example 563of this is to enable SLIP compression, or to select the connector type 564for some Ethernet cards. 565Refer to the man page for the specific driver 566for more information. 567.Sm off 568.It Fl link Op Cm 0 No - Cm 2 569.Sm on 570Disable special processing at the link level with the specified interface. 571.It Cm monitor 572Put the interface in monitor mode. 573No packets are transmitted, and received packets are discarded after 574.Xr bpf 4 575processing. 576.It Fl monitor 577Take the interface out of monitor mode. 578.It Cm up 579Mark an interface 580.Dq up . 581This may be used to enable an interface after an 582.Dq Nm Cm down . 583It happens automatically when setting the first address on an interface. 584If the interface was reset when previously marked down, 585the hardware will be re-initialized. 586.It Cm ssid Ar ssid 587For IEEE 802.11 wireless interfaces, set the desired Service Set 588Identifier (aka network name). 589The SSID is a string up to 32 characters 590in length and may be specified as either a normal string or in 591hexadecimal when proceeded by 592.Ql 0x . 593Additionally, the SSID may be cleared by setting it to 594.Ql - . 595.It Cm nwid Ar ssid 596Another name for the 597.Cm ssid 598parameter. 599Included for 600.Nx 601compatibility. 602.It Cm stationname Ar name 603For IEEE 802.11 wireless interfaces, set the name of this station. 604It appears that the station name is not really part of the IEEE 802.11 605protocol though all interfaces seem to support it. 606As such it only 607seems to be meaningful to identical or virtually identical equipment. 608Setting the station name is identical in syntax to setting the SSID. 609.It Cm station Ar name 610Another name for the 611.Cm stationname 612parameter. 613Included for 614.Bsx 615compatibility. 616.It Cm channel Ar number 617For IEEE 802.11 wireless interfaces, set the desired channel. 618Channels range from 1 to 14, but the exact selection available 619depends on the region your adaptor was manufactured for. 620Setting 621the channel to 0 will give you the default for your adaptor. 622Many 623adaptors ignore this setting unless you are in ad-hoc mode. 624.It Cm authmode Ar mode 625For IEEE 802.11 wireless interfaces, set the desired authentication mode 626in infrastructure mode. 627Not all adaptors support all modes. 628The set of 629valid modes is 630.Dq Li none , 631.Dq Li open , 632and 633.Dq Li shared . 634Modes are case insensitive. 635.It Cm powersave 636For IEEE 802.11 wireless interfaces, enable powersave mode. 637.It Fl powersave 638For IEEE 802.11 wireless interfaces, disable powersave mode. 639.It Cm powersavesleep Ar sleep 640For IEEE 802.11 wireless interfaces, set the desired max powersave sleep 641time in milliseconds. 642.It Cm protmode Ar technique 643For IEEE 802.11 wireless interfaces operating in 11g, use the specified 644.Ar technique 645for protecting OFDM frames in a mixed 11b/11g network. 646The set of valid techniques is 647.Dq Li off , 648.Dq Li cts 649(CTS to self), 650and 651.Dq Li rtscts 652(RTS/CTS). 653Technique names are case insensitive. 654.It Cm rtsthreshold Ar length 655For IEEE 802.11 wireless interfaces, set the threshold for which 656transmitted frames are preceded by transmission of an 657RTS 658control frame. 659The 660.Ar length 661argument 662is the frame size in bytes and must be in the range 1 to 2312. 663Not all adaptors support setting the RTS threshold. 664.It Cm txpower Ar power 665For IEEE 802.11 wireless interfaces, set the power used to transmit frames. 666The 667.Ar power 668argument 669is a unitless value in the range 0 to 100 that is interpreted 670by drivers to derive a device-specific value. 671Out of range values are truncated. 672Typically only a few discreet power settings are available and 673the driver will use the setting closest to the specified value. 674Not all adaptors support changing the transmit power. 675.It Cm wepmode Ar mode 676For IEEE 802.11 wireless interfaces, set the desired WEP mode. 677Not all adaptors support all modes. 678The set of valid modes is 679.Dq Li off , 680.Dq Li on , 681and 682.Dq Li mixed . 683The 684.Dq Li mixed 685mode explicitly tells the adaptor to allow association with access 686points which allow both encrypted and unencrypted traffic. 687On these adaptors, 688.Dq Li on 689means that the access point must only allow encrypted connections. 690On other adaptors, 691.Dq Li on 692is generally another name for 693.Dq Li mixed . 694Modes are case insensitive. 695.It Cm weptxkey Ar index 696For IEEE 802.11 wireless interfaces, set the WEP key to be used for 697transmission. 698.It Cm wepkey Ar key Ns | Ns Ar index : Ns Ar key 699For IEEE 802.11 wireless interfaces, set the selected WEP key. 700If an 701.Ar index 702is not given, key 1 is set. 703A WEP key will be either 5 or 13 704characters (40 or 104 bits) depending of the local network and the 705capabilities of the adaptor. 706It may be specified either as a plain 707string or as a string of hexadecimal digits proceeded by 708.Ql 0x . 709For maximum portability, hex keys are recommended; 710the mapping of text keys to WEP encryption is usually driver-specific. 711In particular, the 712.Tn Windows 713drivers do this mapping differently to 714.Fx . 715A key may be cleared by setting it to 716.Ql - . 717If WEP is supported then there are at least four keys. 718Some adaptors support more than four keys. 719If that is the case, then the first four keys 720(1-4) will be the standard temporary keys and any others will be adaptor 721specific keys such as permanent keys stored in NVRAM. 722.It Cm wep 723Another way of saying 724.Cm wepmode on . 725Included for 726.Bsx 727compatibility. 728.It Fl wep 729Another way of saying 730.Cm wepmode off . 731Included for 732.Bsx 733compatibility. 734.It Cm nwkey key 735Another way of saying: 736.Pp 737.Dq Li "wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey 4:-" . 738.Pp 739Included for 740.Nx 741compatibility. 742.It Cm nwkey Xo 743.Sm off 744.Ar n : k1 , k2 , k3 , k4 745.Sm on 746.Xc 747Another way of saying 748.Pp 749.Dq Li "wepmode on weptxkey n wepkey 1:k1 wepkey 2:k2 wepkey 3:k3 wepkey 4:k4" . 750.Pp 751Included for 752.Nx 753compatibility. 754.It Fl nwkey 755Another way of saying 756.Cm wepmode off . 757.Pp 758Included for 759.Nx 760compatibility. 761.El 762.Pp 763The 764.Nm 765utility displays the current configuration for a network interface 766when no optional parameters are supplied. 767If a protocol family is specified, 768.Nm 769will report only the details specific to that protocol family. 770.Pp 771If the driver does supports the media selection system, the supported 772media list will be included in the output. 773.Pp 774If the 775.Fl m 776flag is passed before an interface name, 777.Nm 778will display the capability list and all 779of the supported media for the specified interface. 780If 781.Fl L 782flag is supplied, address lifetime is displayed for IPv6 addresses, 783as time offset string. 784.Pp 785Optionally, the 786.Fl a 787flag may be used instead of an interface name. 788This flag instructs 789.Nm 790to display information about all interfaces in the system. 791The 792.Fl d 793flag limits this to interfaces that are down, and 794.Fl u 795limits this to interfaces that are up. 796When no arguments are given, 797.Fl a 798is implied. 799.Pp 800The 801.Fl l 802flag may be used to list all available interfaces on the system, with 803no other additional information. 804Use of this flag is mutually exclusive 805with all other flags and commands, except for 806.Fl d 807(only list interfaces that are down) 808and 809.Fl u 810(only list interfaces that are up). 811.Pp 812The 813.Fl C 814flag may be used to list all of the interface cloners available on 815the system, with no additional information. 816Use of this flag is mutually exclusive with all other flags and commands. 817.Pp 818Only the super-user may modify the configuration of a network interface. 819.Sh NOTES 820The media selection system is relatively new and only some drivers support 821it (or have need for it). 822.Sh DIAGNOSTICS 823Messages indicating the specified interface does not exist, the 824requested address is unknown, or the user is not privileged and 825tried to alter an interface's configuration. 826.Sh BUGS 827Basic IPv6 node operation requires a link-local address on each 828interface configured for IPv6. 829Normally, such an address is automatically configured by the 830kernel on each interface added to the system; this behaviour may 831be disabled by setting the sysctl MIB variable 832.Va net.inet6.ip6.auto_linklocal 833to 0. 834.Pp 835If you delete such an address using 836.Nm , 837the kernel may act very oddly. 838Do this at your own risk. 839.Sh SEE ALSO 840.Xr netstat 1 , 841.Xr netintro 4 , 842.Xr vlan 4 , 843.\" .Xr eon 5 , 844.Xr rc 8 , 845.Xr routed 8 , 846.Xr sysctl 8 847.Sh HISTORY 848The 849.Nm 850utility appeared in 851.Bx 4.2 . 852