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