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.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgment: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" From: @(#)ifconfig.8 8.3 (Berkeley) 1/5/94 33.\" $FreeBSD$ 34.\" 35.Dd February 13, 1996 36.Dt IFCONFIG 8 37.Os BSD 4.2 38.Sh NAME 39.Nm ifconfig 40.Nd configure network interface parameters 41.Sh SYNOPSIS 42.Nm ifconfig 43.Op Fl L 44.Ar interface 45.Op Ar address_family 46.Oo 47.Ar address 48.Op Ar dest_address 49.Oc 50.Op Ar parameters 51.Nm ifconfig 52.Fl a 53.Op Fl L 54.Op Fl d 55.Op Fl u 56.Op Ar address_family 57.Nm ifconfig 58.Fl l 59.Op Fl d 60.Op Fl u 61.Op Ar address_family 62.Nm ifconfig 63.Op Fl L 64.Op Fl d 65.Op Fl u 66.Sh DESCRIPTION 67.Nm Ifconfig 68is used to assign an address 69to a network interface and/or configure 70network interface parameters. 71.Nm Ifconfig 72must be used at boot time to define the network address 73of each interface present on a machine; it may also be used at 74a later time to redefine an interface's address 75or other operating parameters. 76.Pp 77The following options are available: 78.Bl -tag -width indent 79.It Ar address 80For the 81.Tn DARPA Ns -Internet 82family, 83the address is either a host name present in the host name data 84base, 85.Xr hosts 5 , 86or a 87.Tn DARPA 88Internet address expressed in the Internet standard 89.Dq dot notation . 90.\" For the Xerox Network Systems(tm) family, 91.\" addresses are 92.\" .Ar net:a.b.c.d.e.f , 93.\" where 94.\" .Ar net 95.\" is the assigned network number (in decimal), 96.\" and each of the six bytes of the host number, 97.\" .Ar a 98.\" through 99.\" .Ar f , 100.\" are specified in hexadecimal. 101.\" The host number may be omitted on 10Mb/s Ethernet interfaces, 102.\" which use the hardware physical address, 103.\" and on interfaces other than the first. 104.\" For the 105.\" .Tn ISO 106.\" family, addresses are specified as a long hexadecimal string, 107.\" as in the Xerox family. However, two consecutive dots imply a zero 108.\" byte, and the dots are optional, if the user wishes to (carefully) 109.\" count out long strings of digits in network byte order. 110.It Ar address_family 111Specify the 112.Ar "address family" 113which affects interpretation of the remaining parameters. 114Since an interface can receive transmissions in differing protocols 115with different naming schemes, specifying the address family is recommended. 116The address or protocol families currently 117supported are 118.Dq inet , 119.Dq inet6 , 120.Dq atalk , 121.Dq ether , 122.\" .Dq iso , 123and 124.Dq ipx . 125.\" and 126.\" .Dq ns . 127.It Ar dest_address 128Specify the address of the correspondent on the other end 129of a point to point link. 130.It Ar interface 131This 132parameter is a string of the form 133.Dq name unit , 134for example, 135.Dq en0 . 136.El 137.Pp 138The following parameters may be set with 139.Nm ifconfig : 140.Bl -tag -width indent 141.It Cm add 142Another name for the ``alias'' parameter. Introduced for compatibility 143with BSD/OS. 144.It Cm alias 145Establish an additional network address for this interface. 146This is sometimes useful when changing network numbers, and 147one wishes to accept packets addressed to the old interface. 148If the address is on the same subnet as the first network address 149for this interface, a netmask of 0xffffffff has to be specified. 150.It Fl alias 151Remove the network address specified. 152This would be used if you incorrectly specified an alias, or it 153was no longer needed. 154If you have incorrectly set an NS address having the side effect 155of specifying the host portion, removing all NS addresses will 156allow you to respecify the host portion. 157.It Cm anycast 158(Inet6 only) 159Specify that the address configured is an anycast address. 160Based on the current specification, 161only routers may configure anycast addresses. 162Anycast address will not be used as source address of any of outgoing 163IPv6 packets. 164.It Cm arp 165Enable the use of the Address Resolution Protocol in mapping 166between network level addresses and link level addresses (default). 167This is currently implemented for mapping between 168.Tn DARPA 169Internet 170addresses and 10Mb/s Ethernet addresses. 171.It Fl arp 172Disable the use of the Address Resolution Protocol. 173.It Cm broadcast 174(Inet only) 175Specify the address to use to represent broadcasts to the 176network. 177The default broadcast address is the address with a host part of all 1's. 178.It Cm debug 179Enable driver dependent debugging code; usually, this turns on 180extra console error logging. 181.It Fl debug 182Disable driver dependent debugging code. 183.It Cm delete 184Another name for the ``-alias'' parameter. 185.It Cm down 186Mark an interface ``down''. When an interface is 187marked ``down'', the system will not attempt to 188transmit messages through that interface. 189If possible, the interface will be reset to disable reception as well. 190This action does not automatically disable routes using the interface. 191.\" .It Cm ipdst 192.\" This is used to specify an Internet host who is willing to receive 193.\" ip packets encapsulating NS packets bound for a remote network. 194.\" An apparent point to point link is constructed, and 195.\" the address specified will be taken as the NS address and network 196.\" of the destination. 197.\" IP encapsulation of 198.\" .Tn CLNP 199.\" packets is done differently. 200.It Cm lladdr Ar addr 201Set the link-level address on an interface. This can be used to 202e.g. set a new MAC address on an ethernet interface, though the 203mechanism used is not ethernet-specific. The address 204.Ar addr 205is specified as a series of colon-separated hex digits. 206If the interface is already 207up when this option is used, it will be briefly brought down and 208then brought back up again in order to insure that the receive 209filter in the underlying ethernet hardware is properly reprogrammed. 210.It Cm media Ar type 211If the driver supports the media selection system, set the media type 212of the interface to 213.Ar type . 214Some interfaces support the mutually exclusive use of one of several 215different physical media connectors. For example, a 10Mb/s Ethernet 216interface might support the use of either 217.Tn AUI 218or twisted pair connectors. Setting the media type to 219.Dq 10base5/AUI 220would change the currently active connector to the AUI port. 221Setting it to 222.Dq 10baseT/UTP 223would activate twisted pair. Refer to the interfaces' driver 224specific documentation or man page for a complete list of the 225available types. 226.It Cm mediaopt Ar opts 227If the driver supports the media selection system, set the specified 228media options on the interface. 229.Ar Opts 230is a comma delimited list of options to apply to the interface. 231Refer to the interfaces' driver specific man page for a complete 232list of available options. 233.It Fl mediaopt Ar opts 234If the driver supports the media selection system, disable the 235specified media options on the interface. 236.It Cm vlan Ar vlan_tag 237If the interface is a vlan pseudo interface, set the vlan tag value 238to 239.Ar vlan_tag . 240This value is a 16-bit number which is used to create an 802.1Q 241vlan header for packets sent from the vlan interface. 242Note that 243.Cm vlan 244and 245.Cm vlandev 246must both be set at the same time. 247.It Cm vlandev Ar iface 248If the interface is a vlan pseudo device, associate physical interface 249.Ar iface 250with it. 251Packets transmitted through the vlan interface will be 252diverted to the specified physical interface 253.Ar iface 254with 802.1Q vlan encapsulation. 255Packets with 802.1Q encapsulation received 256by the parent interface with the correct vlan tag will be diverted to 257the associated vlan pseudo-interface. 258The vlan interface is assigned a 259copy of the parent interface's flags and the parent's ethernet address. 260The 261.Cm vlandev 262and 263.Cm vlan 264must both be set at the same time. 265If the vlan interface already has 266a physical interface associated with it, this command will fail. 267To 268change the association to another physical interface, the existing 269association must be cleared first. 270.Pp 271Note: if the 272.Ar link0 273flag is set on the vlan interface, the vlan pseudo 274interface's behavior changes: the 275.Ar link0 276tells the vlan interface that the 277parent interface supports insertion and extraction of vlan tags on its 278own (usually in firmware) and that it should pass packets to and from 279the parent unaltered. 280.It Fl vlandev Ar iface 281If the driver is a vlan pseudo device, disassociate the physical interface 282.Ar iface 283from it. 284This breaks the link between the vlan interface and its parent, 285clears its vlan tag, flags and its link address and shuts the interface down. 286.It Cm metric Ar n 287Set the routing metric of the interface to 288.Ar n , 289default 0. 290The routing metric is used by the routing protocol 291.Pq Xr routed 8 . 292Higher metrics have the effect of making a route 293less favorable; metrics are counted as addition hops 294to the destination network or host. 295.It Cm mtu Ar n 296Set the maximum transmission unit of the interface to 297.Ar n , 298default is interface specific. 299The mtu is used to limit the size of packets that are transmitted on an 300interface. 301Not all interfaces support setting the mtu, and some interfaces have 302range restrictions. 303.It Cm netmask Ar mask 304.\" (Inet and ISO) 305(Inet only) 306Specify how much of the address to reserve for subdividing 307networks into sub-networks. 308The mask includes the network part of the local address 309and the subnet part, which is taken from the host field of the address. 310The mask can be specified as a single hexadecimal number 311with a leading 0x, with a dot-notation Internet address, 312or with a pseudo-network name listed in the network table 313.Xr networks 5 . 314The mask contains 1's for the bit positions in the 32-bit address 315which are to be used for the network and subnet parts, 316and 0's for the host part. 317The mask should contain at least the standard network portion, 318and the subnet field should be contiguous with the network 319portion. 320.It Cm prefixlen Ar len 321(Inet6 only) 322Specify that 323.Ar len 324bits are reserved for subdividing networks into sub-networks. 325The 326.Ar len 327must be integer, and for syntactical reason it must be between 0 to 128. 328It is almost always 64 under the current IPv6 assignment rule. 329If the parameter is ommitted, 64 is used. 330.\" see 331.\" Xr eon 5 . 332.\" .It Cm nsellength Ar n 333.\" .Pf ( Tn ISO 334.\" only) 335.\" This specifies a trailing number of bytes for a received 336.\" .Tn NSAP 337.\" used for local identification, the remaining leading part of which is 338.\" taken to be the 339.\" .Tn NET 340.\" (Network Entity Title). 341.\" The default value is 1, which is conformant to US 342.\" .Tn GOSIP . 343.\" When an ISO address is set in an ifconfig command, 344.\" it is really the 345.\" .Tn NSAP 346.\" which is being specified. 347.\" For example, in 348.\" .Tn US GOSIP , 349.\" 20 hex digits should be 350.\" specified in the 351.\" .Tn ISO NSAP 352.\" to be assigned to the interface. 353.\" There is some evidence that a number different from 1 may be useful 354.\" for 355.\" .Tn AFI 356.\" 37 type addresses. 357.It Cm range 358Under appletalk, set the interface to respond to a 359.Em netrange. 360of the form startnet-endnet. 361Appletalk uses this scheme instead of 362netmasks though 363.Fx 364implements it internally as a set of netmasks. 365.It Cm remove 366Another name for the ``-alias'' parameter. Introduced for compatibility 367with BSD/OS. 368.It Cm phase 369The argument following this specifies the version (phase) of the 370Appletalk network attached to the interface. 371Values of 1 or 2 are permitted. 372.It Cm link[0-2] 373Enable special processing of the link level of the interface. 374These three options are interface specific in actual effect, however, 375they are in general used to select special modes of operation. 376An example 377of this is to enable SLIP compression, or to select the connector type 378for some Ethernet cards. Refer to the man page for the specific driver 379for more information. 380.It Fl link[0-2] 381Disable special processing at the link level with the specified interface. 382.It Cm up 383Mark an interface 384.Dq up . 385This may be used to enable an interface after an 386.Dq ifconfig down . 387It happens automatically when setting the first address on an interface. 388If the interface was reset when previously marked down, 389the hardware will be re-initialized. 390.El 391.Pp 392.Nm Ifconfig 393displays the current configuration for a network interface 394when no optional parameters are supplied. 395If a protocol family is specified, 396.Nm 397will report only the details specific to that protocol family. 398.Pp 399If the driver does supports the media selection system, the supported 400media list will be included in the output. 401.Pp 402If 403.Fl L 404flag is supplied, address lifetime is dislayed for IPv6 addresses, 405as time offset string. 406.Pp 407Optionally, the 408.Fl a 409flag may be used instead of an interface name. This flag instructs 410.Nm 411to display information about all interfaces in the system. 412The 413.Fl d 414flag limits this to interfaces that are down, and 415.Fl u 416limits this to interfaces that are up. 417When no arguments are given, 418.Fl a 419is implied. 420.Pp 421The 422.Fl l 423flag may be used to list all available interfaces on the system, with 424no other additional information. Use of this flag is mutually exclusive 425with all other flags and commands, except for 426.Fl d 427(only list interfaces that are down) 428and 429.Fl u 430(only list interfaces that are up). 431.Pp 432Only the super-user may modify the configuration of a network interface. 433.Sh NOTES 434The media selection system is relatively new and only some drivers support 435it (or have need for it). 436.Sh DIAGNOSTICS 437Messages indicating the specified interface does not exist, the 438requested address is unknown, or the user is not privileged and 439tried to alter an interface's configuration. 440.Sh BUGS 441IPv6 link-local addresses are required for several basic communication 442between IPv6 node. 443If they are deleted by 444.Nm ifconfig 445manually, the kernel might show very strange behavior. 446So, such manual deletions are strongly discouraged. 447.Sh SEE ALSO 448.Xr netstat 1 , 449.Xr netintro 4 , 450.Xr rc 8 , 451.Xr routed 8 452.\" .Xr eon 5 453.Sh HISTORY 454The 455.Nm 456command appeared in 457.Bx 4.2 . 458