1.\" $NetBSD: ifconfig.8,v 1.102 2010/11/15 22:42:37 pooka Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)ifconfig.8 8.4 (Berkeley) 6/1/94 31.\" 32.Dd November 15, 2010 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 N 41.Ar interface address_family 42.Oo 43.Ar address 44.Op Ar dest_address 45.Oc 46.Op Ar parameters 47.Nm 48.Op Fl hLmNvz 49.Ar interface 50.Op Ar protocol_family 51.Nm 52.Fl a 53.Op Fl bdhLNmsuvz 54.Op Ar protocol_family 55.Nm 56.Fl l 57.Op Fl bdsu 58.Nm 59.Fl s 60.Ar interface 61.Nm 62.Fl C 63.Sh DESCRIPTION 64.Nm 65is used to assign an address 66to a network interface and/or configure 67network interface parameters. 68.Nm 69must be used at boot time to define the network address 70of each interface present on a machine; it may also be used at 71a later time to redefine an interface's address 72or other operating parameters. 73.Pp 74Available operands for 75.Nm : 76.Bl -tag -width Ds 77.It Ar address 78For the 79.Tn DARPA-Internet 80family, 81the address is either a host name present in the host name data 82base, 83.Xr hosts 5 , 84or a 85.Tn DARPA 86Internet address expressed in the Internet standard 87.Dq dot notation . 88For the Xerox Network Systems(tm) family, 89addresses are 90.Ar net:a.b.c.d.e.f , 91where 92.Ar net 93is the assigned network number 94.Pq in decimal , 95and each of the six bytes of the host number, 96.Ar a 97through 98.Ar f , 99are specified in hexadecimal. 100The host number may be omitted on Ethernet interfaces, 101which use the hardware physical address, 102and on interfaces other than the first. 103For the 104.Tn ISO 105family, addresses are specified as a long hexadecimal string, 106as in the Xerox family. 107However, two consecutive dots imply a zero 108byte, and the dots are optional, if the user wishes to 109.Pq carefully 110count out long strings of digits in network byte order. 111.It Ar address_family 112Specifies the 113.Ar address_family 114which affects interpretation of the remaining parameters. 115Since an interface can receive transmissions in differing protocols 116with different naming schemes, specifying the address family is recommended. 117The address or protocol families currently 118supported are 119.Dq inet , 120.Dq inet6 , 121.Dq atalk , 122.Dq iso , 123and 124.Dq link . 125.It Ar interface 126The 127.Ar interface 128parameter is a string of the form 129.Dq name unit , 130for example, 131.Dq en0 132.El 133.Pp 134The following parameters may be set with 135.Nm : 136.Bl -tag -width dest_addressxx 137.It Cm active 138This keyword applies when 139.Nm 140adds or modifies any link-layer address. 141It indicates that 142.Nm 143should 144.Dq activate 145the address. 146Activation makes an address the default source for transmissions 147on the interface. 148You may not delete the active address from an interface. 149You must activate some other address, first. 150.It Cm advbase Ar n 151If the driver is a 152.Xr carp 4 153pseudo-device, set the base advertisement interval to 154.Ar n 155seconds. 156This ia an 8-bit number; the default value is 1 second. 157.It Cm advskew Ar n 158If the driver is a 159.Xr carp 4 160pseudo-device, skew the advertisement interval by 161.Ar n . 162This is an 8-bit number; the default value is 0. 163.Pp 164Taken together the 165.Cm advbase 166indicate how frequently, in seconds, the host will advertise the fact that it 167considers itself the master of the virtual host. 168The formula is 169.Cm advbase 170+ 171.Pf ( Cm advskew 172/ 256). 173If the master does not advertise within three times this interval, this host 174will begin advertising as master. 175.It Cm alias 176Establish an additional network address for this interface. 177This is sometimes useful when changing network numbers, and 178one wishes to accept packets addressed to the old interface. 179.It Fl alias 180Remove the specified network address alias. 181.It Cm arp 182Enable the use of the Address Resolution Protocol in mapping 183between network level addresses and link level addresses 184.Pq default . 185This is currently implemented for mapping between 186.Tn DARPA 187Internet 188addresses and Ethernet addresses. 189.It Fl arp 190Disable the use of the Address Resolution Protocol. 191.It Cm anycast 192.Pq inet6 only 193Set the IPv6 anycast address bit. 194.It Fl anycast 195.Pq inet6 only 196Clear the IPv6 anycast address bit. 197.It Cm broadcast Ar mask 198.Pq Inet only 199Specify the address to use to represent broadcasts to the 200network. 201The default broadcast address is the address with a host part of all 1's. 202.It Cm carpdev Ar iface 203If the driver is a 204.Xr carp 4 205pseudo-device, attach it to 206.Ar iface . 207If not specified, the kernel will attempt to select an interface with 208a subnet matching that of the carp interface. 209.It Cm debug 210Enable driver dependent debugging code; usually, this turns on 211extra console error logging. 212.It Fl debug 213Disable driver dependent debugging code. 214.It Cm delete 215Remove the network address specified. 216This would be used if you incorrectly specified an alias, or it 217was no longer needed. 218If you have incorrectly set an NS address having the side effect 219of specifying the host portion, removing all NS addresses will 220allow you to respecify the host portion. 221.Cm delete 222does not work for IPv6 addresses. 223Use 224.Fl alias 225with explicit IPv6 address instead. 226.It Ar dest_address 227Specify the address of the correspondent on the other end 228of a point to point link. 229.It Cm down 230Mark an interface ``down''. 231When an interface is 232marked ``down'', the system will not attempt to 233transmit messages through that interface. 234If possible, the interface will be reset to disable reception as well. 235This action does not automatically disable routes using the interface. 236.It Cm ipdst 237This is used to specify an Internet host who is willing to receive 238ip packets encapsulating NS packets bound for a remote network. 239An apparent point to point link is constructed, and 240the address specified will be taken as the NS address and network 241of the destination. 242IP encapsulation of 243.Tn CLNP 244packets is done differently. 245.It Cm media Ar type 246Set the media type of the interface to 247.Ar type . 248Some interfaces support the mutually exclusive use of one of several 249different physical media connectors. 250For example, a 10Mb/s Ethernet 251interface might support the use of either 252.Tn AUI 253or twisted pair connectors. 254Setting the media type to 255.Dq 10base5 256or 257.Dq AUI 258would change the currently active connector to the AUI port. 259Setting it to 260.Dq 10baseT 261or 262.Dq UTP 263would activate twisted pair. 264Refer to the interfaces' driver 265specific man page for a complete list of the available types 266and the 267.Xr ifmedia 4 268manual page for a list of media types. 269See the 270.Fl m 271flag below. 272.It Cm mediaopt Ar opts 273Set the specified media options on the interface. 274.Ar opts 275is a comma delimited list of options to apply to the interface. 276Refer to the interfaces' driver specific man page for a complete 277list of available options. 278Also see the 279.Xr ifmedia 4 280manual page for a list of media options. 281.It Fl mediaopt Ar opts 282Disable the specified media options on the interface. 283.It Cm mode Ar mode 284If the driver supports the media selection system, set the specified 285operating mode on the interface to 286.Ar mode . 287For IEEE 802.11 wireless interfaces that support multiple operating modes 288this directive is used to select between 802.11a 289.Pq Dq 11a , 290802.11b 291.Pq Dq 11b , 292and 802.11g 293.Pq Dq 11g 294operating modes. 295.It Cm instance Ar minst 296Set the media instance to 297.Ar minst . 298This is useful for devices which have multiple physical layer interfaces 299.Pq PHYs . 300Setting the instance on such devices may not be strictly required 301by the network interface driver as the driver may take care of this 302automatically; see the driver's manual page for more information. 303.It Cm metric Ar n 304Set the routing metric of the interface to 305.Ar n , 306default 0. 307The routing metric is used by the routing protocol 308.Pq Xr routed 8 . 309Higher metrics have the effect of making a route 310less favorable; metrics are counted as addition hops 311to the destination network or host. 312.It Cm mtu Ar n 313Set the maximum transmission unit of the interface to 314.Ar n . 315Most interfaces don't support this option. 316.It Cm netmask Ar mask 317.Pq inet, inet6, and ISO 318Specify how much of the address to reserve for subdividing 319networks into sub-networks. 320The mask includes the network part of the local address 321and the subnet part, which is taken from the host field of the address. 322The mask can be specified as a single hexadecimal number 323with a leading 0x, with a dot-notation Internet address, 324or with a pseudo-network name listed in the network table 325.Xr networks 5 . 326The mask contains 1's for the bit positions in the 32-bit address 327which are to be used for the network and subnet parts, 328and 0's for the host part. 329The mask should contain at least the standard network portion, 330and the subnet field should be contiguous with the network 331portion. 332.Pp 333For INET and INET6 addresses, the netmask can also be given with 334slash-notation after the address 335.Pq e.g 192.168.17.3/24 . 336.\" see 337.\" Xr eon 5 . 338.It Cm nsellength Ar n 339.Pf ( Tn ISO 340only) 341This specifies a trailing number of bytes for a received 342.Tn NSAP 343used for local identification, the remaining leading part of which is 344taken to be the 345.Tn NET 346.Pq Network Entity Title . 347The default value is 1, which is conformant to US 348.Tn GOSIP . 349When an ISO address is set in an ifconfig command, 350it is really the 351.Tn NSAP 352which is being specified. 353For example, in 354.Tn US GOSIP , 35520 hex digits should be 356specified in the 357.Tn ISO NSAP 358to be assigned to the interface. 359There is some evidence that a number different from 1 may be useful 360for 361.Tn AFI 36237 type addresses. 363.It Cm state Ar state 364Explicitly force the 365.Xr carp 4 366pseudo-device to enter this state. 367Valid states are 368.Ar init , 369.Ar backup , 370and 371.Ar master . 372.It Cm frag Ar threshold 373.Pq IEEE 802.11 devices only 374Configure the fragmentation threshold for IEEE 802.11-based wireless 375network interfaces. 376.It Cm rts Ar threshold 377.Pq IEEE 802.11 devices only 378Configure the RTS/CTS threshold for IEEE 802.11-based wireless 379network interfaces. 380This controls the number of bytes used for the RTS/CTS handshake boundary. 381The 382.Ar threshold 383can be any value between 0 and 2347. 384The default is 2347, which indicates the RTS/CTS mechanism should not be used. 385.It Cm ssid Ar id 386.Pq IEEE 802.11 devices only 387Configure the Service Set Identifier (a.k.a. the network name) 388for IEEE 802.11-based wireless network interfaces. 389The 390.Ar id 391can either be any text string up to 32 characters in length, 392or a series of up to 64 hexadecimal digits preceded by 393.Dq 0x . 394Setting 395.Ar id 396to the empty string allows the interface to connect to any available 397access point. 398.It Cm nwid Ar id 399Synonym for 400.Dq ssid . 401.It Cm hidessid 402.Pq IEEE 802.11 devices only 403When operating as an access point, do not broadcast the SSID 404in beacon frames or respond to probe request frames unless 405they are directed to the ap (i.e., they include the ap's SSID). 406By default, the SSID is included in beacon frames and 407undirected probe request frames are answered. 408.It Fl hidessid 409.Pq IEEE 802.11 devices only 410When operating as an access point, broadcast the SSID 411in beacon frames and answer and respond to undirected probe 412request frames (default). 413.It Cm nwkey Ar key 414.Pq IEEE 802.11 devices only 415Enable WEP encryption for IEEE 802.11-based wireless network interfaces 416with the 417.Ar key . 418The 419.Ar key 420can either be a string, a series of hexadecimal digits preceded by 421.Dq 0x , 422or a set of keys in the form 423.Ar n:k1,k2,k3,k4 , 424where 425.Ar n 426specifies which of keys will be used for all transmitted packets, 427and four keys, 428.Ar k1 429through 430.Ar k4 , 431are configured as WEP keys. 432Note that the order must be match within same network if multiple keys 433are used. 434For IEEE 802.11 wireless network, the length of each key is restricted to 43540 bits, i.e. 5-character string or 10 hexadecimal digits, 436while the WaveLAN/IEEE Gold cards accept the 104 bits 437.Pq 13 characters 438key. 439.It Cm nwkey Cm persist 440.Pq IEEE 802.11 devices only 441Enable WEP encryption for IEEE 802.11-based wireless network interfaces 442with the persistent key written in the network card. 443.It Cm nwkey Cm persist: Ns Ar key 444.Pq IEEE 802.11 devices only 445Write the 446.Ar key 447to the persistent memory of the network card, and 448enable WEP encryption for IEEE 802.11-based wireless network interfaces 449with the 450.Ar key . 451.It Fl nwkey 452.Pq IEEE 802.11 devices only 453Disable WEP encryption for IEEE 802.11-based wireless network interfaces. 454.It Cm apbridge 455.Pq IEEE 802.11 devices only 456When operating as an access point, pass packets between 457wireless clients directly (default). 458.It Fl apbridge 459.Pq IEEE 802.11 devices only 460When operating as an access point, pass packets through 461the system so that they can be forwared using some other mechanism. 462Disabling the internal bridging is useful when traffic 463is to be processed with packet filtering. 464.It Cm pass Ar passphrase 465If the driver is a 466.Xr carp 4 467pseudo-device, set the authentication key to 468.Ar passphrase . 469There is no passphrase by default 470.It Cm powersave 471.Pq IEEE 802.11 devices only 472Enable 802.11 power saving mode. 473.It Fl powersave 474.Pq IEEE 802.11 devices only 475Disable 802.11 power saving mode. 476.It Cm powersavesleep Ar duration 477.Pq IEEE 802.11 devices only 478Set the receiver sleep duration in milliseconds for 802.11 power saving mode. 479.It Cm bssid Ar bssid 480.Pq IEEE 802.11 devices only 481Set the desired BSSID for IEEE 802.11-based wireless network interfaces. 482.It Fl bssid 483.Pq IEEE 802.11 devices only 484Unset the desired BSSID for IEEE 802.11-based wireless network interfaces. 485The interface will automatically select a BSSID in this mode, which is 486the default. 487.It Cm chan Ar chan 488.Pq IEEE 802.11 devices only 489Select the channel 490.Pq radio frequency 491to be used for IEEE 802.11-based wireless network interfaces. 492.It Fl chan 493.Pq IEEE 802.11 devices only 494Unset the desired channel to be used 495for IEEE 802.11-based wireless network interfaces. 496It doesn't affect the channel to be created for IBSS or hostap mode. 497.It Cm list scan 498.Pq IEEE 802.11 devices only 499Display the access points and/or ad-hoc neighbors 500located in the vicinity. 501The 502.Fl v 503flag may be used to display long SSIDs. 504.Fl v 505also causes received information elements to be displayed symbolicaly. 506Only the super-user can use this command. 507.It Cm tunnel Ar src_addr Ns Op Ar ,src_port 508.Ar dest_addr Ns Op Ar ,dest_port 509.Pq IP tunnel devices only 510Configure the physical source and destination address for IP tunnel 511interfaces, including 512.Xr gif 4 . 513The arguments 514.Ar src_addr 515and 516.Ar dest_addr 517are interpreted as the outer source/destination for the encapsulating 518IPv4/IPv6 header. 519.Pp 520On a 521.Xr gre 4 522interface in UDP mode, the arguments 523.Ar src_port 524and 525.Ar dest_port 526are interpreted as the outer source/destination port for the encapsulating 527UDP header. 528.It Cm deletetunnel 529Unconfigure the physical source and destination address for IP tunnel 530interfaces previously configured with 531.Cm tunnel . 532.It Cm create 533Create the specified network pseudo-device. 534.It Cm destroy 535Destroy the specified network pseudo-device. 536.It Cm pltime Ar n 537.Pq inet6 only 538Set preferred lifetime for the address. 539.It Cm prefixlen Ar n 540.Pq inet and inet6 only 541Effect is similar to 542.Cm netmask . 543but you can specify by prefix length by digits. 544.It Cm deprecated 545.Pq inet6 only 546Set the IPv6 deprecated address bit. 547.It Fl deprecated 548.Pq inet6 only 549Clear the IPv6 deprecated address bit. 550.It Cm tentative 551.Pq inet6 only 552Set the IPv6 tentative address bit. 553.It Fl tentative 554.Pq inet6 only 555Clear the IPv6 tentative address bit. 556.It Cm eui64 557.Pq inet6 only 558Fill interface index 559.Pq lowermost 64bit of an IPv6 address 560automatically. 561.It Cm link[0-2] 562Enable special processing of the link level of the interface. 563These three options are interface specific in actual effect, however, 564they are in general used to select special modes of operation. 565An example 566of this is to enable SLIP compression, or to select the connector type 567for some Ethernet cards. 568Refer to the man page for the specific driver 569for more information. 570.It Fl link[0-2] 571Disable special processing at the link level with the specified interface. 572.It Cm linkstr 573Set a link-level string parameter for the interface. 574This functionality varies from interface to interface. 575Refer to the man page for the specific driver 576for more information. 577.It Fl linkstr 578Remove an interface link-level string parameter. 579.It Cm up 580Mark an interface ``up''. 581This may be used to enable an interface after an ``ifconfig down.'' 582It happens automatically when setting the first address on an interface. 583If the interface was reset when previously marked down, 584the hardware will be re-initialized. 585.It Cm vhid Ar n 586If the driver is a 587.Xr carp 4 588pseudo-device, set the virtual host ID to 589.Ar n . 590Acceptable values are 1 to 255. 591.It Cm vlan Ar vid 592If the interface is a 593.Xr vlan 4 594pseudo-interface, set the VLAN identifier to 595.Ar vid . 596These are the first 12 bits (0-4095) from a 16-bit integer used 597to create an 802.1Q VLAN header for packets sent from the 598.Xr vlan 4 599interface. 600Note that 601.Cm vlan 602and 603.Cm vlanif 604must be set at the same time. 605.It Cm vlanif Ar iface 606If the interface is a 607.Xr vlan 4 608pseudo-interface, associate the physical interface 609.Ar iface 610with it. 611Packets transmitted through the 612.Xr vlan 4 613interface will be diverted to the specified physical interface 614.Ar iface 615with 802.1Q VLAN encapsulation. 616Packets with 802.1Q encapsulation received 617by the physical interface with the correct VLAN tag will be diverted to the 618associated 619.Xr vlan 4 620pseudo-interface. 621The VLAN interface is assigned a copy of the physical 622interface's flags and 623.Tn Ethernet 624address. 625If the 626.Xr vlan 4 627interface already has a physical interface associated with it, this command 628will fail. 629To change the association to another physical interface, the 630existing association must be cleared first. 631Note that 632.Cm vlanif 633and 634.Cm vlan 635must be set at the same time. 636.It Cm agrport Ar iface 637Add 638.Ar iface 639to the 640.Xr agr 4 641interface. 642.It Cm -agrport Ar iface 643Remove 644.Ar iface 645from the 646.Xr agr 4 647interface. 648.It Cm vltime Ar n 649.Pq inet6 only 650Set valid lifetime for the address. 651.It Cm ip4csum 652Shorthand of 653.Dq ip4csum-tx ip4csum-rx 654.It Cm -ip4csum 655Shorthand of 656.Dq -ip4csum-tx -ip4csum-rx 657.It Cm tcp4csum 658Shorthand of 659.Dq tcp4csum-tx tcp4csum-rx 660.It Cm -tcp4csum 661Shorthand of 662.Dq -tcp4csum-tx -tcp4csum-rx 663.It Cm udp4csum 664Shorthand of 665.Dq udp4csum-tx udp4csum-rx 666.It Cm -udp4csum 667Shorthand of 668.Dq -udp4csum-tx -udp4csum-rx 669.It Cm tcp6csum 670Shorthand of 671.Dq tcp6csum-tx tcp6csum-rx 672.It Cm -tcp6csum 673Shorthand of 674.Dq -tcp6csum-tx -tcp6csum-rx 675.It Cm udp6csum 676Shorthand of 677.Dq udp6csum-tx udp6csum-rx 678.It Cm -udp6csum 679Shorthand of 680.Dq -udp6csum-tx -udp6csum-rx 681.It Cm ip4csum-tx 682Enable hardware-assisted IPv4 header checksums for the out-bound direction. 683.It Cm -ip4csum-tx 684Disable hardware-assisted IPv4 header checksums for the out-bound direction. 685.It Cm ip4csum-rx 686Enable hardware-assisted IPv4 header checksums for the in-bound direction. 687.It Cm -ip4csum-rx 688Disable hardware-assisted IPv4 header checksums for the in-bound direction. 689.It Cm tcp4csum-tx 690Enable hardware-assisted TCP/IPv4 checksums for the out-bound direction. 691.It Cm -tcp4csum-tx 692Disable hardware-assisted TCP/IPv4 checksums for the out-bound direction. 693.It Cm tcp4csum-rx 694Enable hardware-assisted TCP/IPv4 checksums for the in-bound direction. 695.It Cm -tcp4csum-rx 696Disable hardware-assisted TCP/IPv4 checksums for the in-bound direction. 697.It Cm udp4csum-tx 698Enable hardware-assisted UDP/IPv4 checksums for the out-bound direction. 699.It Cm -udp4csum-tx 700Disable hardware-assisted UDP/IPv4 checksums for the out-bound direction. 701.It Cm udp4csum-rx 702Enable hardware-assisted UDP/IPv4 checksums for the in-bound direction. 703.It Cm -udp4csum-rx 704Disable hardware-assisted UDP/IPv4 checksums for the in-bound direction. 705.It Cm tcp6csum-tx 706Enable hardware-assisted TCP/IPv6 checksums for the out-bound direction. 707.It Cm -tcp6csum-tx 708Disable hardware-assisted TCP/IPv6 checksums for the out-bound direction. 709.It Cm tcp6csum-rx 710Enable hardware-assisted TCP/IPv6 checksums for the in-bound direction. 711.It Cm -tcp6csum-rx 712Disable hardware-assisted TCP/IPv6 checksums for the in-bound direction. 713.It Cm udp6csum-tx 714Enable hardware-assisted UDP/IPv6 checksums for the out-bound direction. 715.It Cm -udp6csum-tx 716Disable hardware-assisted UDP/IPv6 checksums for the out-bound direction. 717.It Cm udp6csum-rx 718Enable hardware-assisted UDP/IPv6 checksums for the in-bound direction. 719.It Cm -udp6csum-rx 720Disable hardware-assisted UDP/IPv6 checksums for the in-bound direction. 721.It Cm tso4 722Enable hardware-assisted TCP/IPv4 segmentation on interfaces that 723support it. 724.It Cm -tso4 725Disable hardware-assisted TCP/IPv4 segmentation on interfaces that 726support it. 727.It Cm tso6 728Enable hardware-assisted TCP/IPv6 segmentation on interfaces that 729support it. 730.It Cm -tso6 731Disable hardware-assisted TCP/IPv6 segmentation on interfaces that 732support it. 733.It Cm maxupd Ar n 734If the driver is a 735.Xr pfsync 4 736pseudo-device, indicate the maximum number 737of updates for a single state which can be collapsed into one. 738This is an 8-bit number; the default value is 128. 739.It Cm syncdev Ar iface 740If the driver is a 741.Xr pfsync 4 742pseudo-device, use the specified interface 743to send and receive pfsync state synchronisation messages. 744.It Fl syncdev 745If the driver is a 746.Xr pfsync 4 747pseudo-device, stop sending pfsync state 748synchronisation messages over the network. 749.It Cm syncpeer Ar peer_address 750If the driver is a 751.Xr pfsync 4 752pseudo-device, make the pfsync link point-to-point rather than using 753multicast to broadcast the state synchronisation messages. 754The peer_address is the IP address of the other host taking part in 755the pfsync cluster. 756With this option, 757.Xr pfsync 4 758traffic can be protected using 759.Xr ipsec 4 . 760.It Fl syncpeer 761If the driver is a 762.Xr pfsync 4 763pseudo-device, broadcast the packets using multicast. 764.El 765.Pp 766.Nm 767displays the current configuration for a network interface 768when no optional parameters are supplied. 769If a protocol family is specified, 770.Nm 771will report only the details specific to that protocol 772family. 773.Pp 774If the 775.Fl s 776flag is passed before an interface name, 777.Nm 778will attempt to query the interface for its media status. 779If the 780interface supports reporting media status, and it reports that it does 781not appear to be connected to a network, 782.Nm 783will exit with status of 1 784.Pq false ; 785otherwise, it will exit with a 786zero 787.Pq true 788exit status. 789Not all interface drivers support media 790status reporting. 791.Pp 792If the 793.Fl m 794flag is passed before an interface name, 795.Nm 796will display all of the supported media for the specified interface. 797If the 798.Fl L 799flag is supplied, address lifetime is displayed for IPv6 addresses, 800as time offset string. 801.Pp 802Optionally, the 803.Fl a 804flag may be used instead of an interface name. 805This flag instructs 806.Nm 807to display information about all interfaces in the system. 808.Fl d 809limits this to interfaces that are down, 810.Fl u 811limits this to interfaces that are up, 812.Fl b 813limits this to broadcast interfaces, and 814.Fl s 815omits interfaces which appear not to be connected to a network. 816.Pp 817The 818.Fl l 819flag may be used to list all available interfaces on the system, with 820no other additional information. 821Use of this flag is mutually exclusive 822with all other flags and commands, except for 823.Fl d 824.Pq only list interfaces that are down , 825.Fl u 826.Pq only list interfaces that are up , 827.Fl s 828.Pq only list interfaces that may be connected , 829.Fl b 830.Pq only list broadcast interfaces . 831.Pp 832The 833.Fl C 834flag may be used to list all of the interface cloners available on 835the system, with no additional information. 836Use of this flag is 837mutually exclusive with all other flags and commands. 838.Pp 839The 840.Fl v 841flag prints statistics on packets sent and received on the given 842interface. 843If 844.Fl h 845is used in conjunction with 846.Fl v , 847the byte statistics will be printed in "human-readable" format. 848The 849.Fl z 850flag is identical to the 851.Fl v 852flag except that it zeros the interface input and output statistics 853after printing them. 854.Pp 855The 856.Fl N 857flag is just the opposite of the 858.Fl n 859flag in 860.Xr netstat 1 861or in 862.Xr route 8 : 863it tells 864.Nm 865to try to resolve numbers to hostnames or to service names. 866The default 867.Nm 868behavior is to print numbers instead of names. 869.Pp 870Only the super-user may modify the configuration of a network interface. 871.Sh EXAMPLES 872Add a link-layer (MAC) address to an Ethernet: 873.Pp 874.Ic ifconfig sip0 link 00:11:22:33:44:55 875.Pp 876Add and activate a link-layer (MAC) address: 877.Pp 878.Ic ifconfig sip0 link 00:11:22:33:44:55 active 879.Sh DIAGNOSTICS 880Messages indicating the specified interface does not exist, the 881requested address is unknown, or the user is not privileged and 882tried to alter an interface's configuration. 883.Sh SEE ALSO 884.Xr netstat 1 , 885.Xr agr 4 , 886.Xr carp 4 , 887.Xr ifmedia 4 , 888.Xr netintro 4 , 889.Xr pfsync 4 , 890.Xr vlan 4 , 891.Xr ifconfig.if 5 , 892.\" .Xr eon 5 , 893.Xr rc 8 , 894.Xr routed 8 895.Sh HISTORY 896The 897.Nm 898command appeared in 899.Bx 4.2 . 900