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 atalk , 113.\" .Dq iso , 114and 115.Dq ipx . 116.\" and 117.\" .Dq ns . 118.It Ar dest_address 119Specify the address of the correspondent on the other end 120of a point to point link. 121.It Ar interface 122This 123parameter is a string of the form 124.Dq name unit , 125for example, 126.Dq en0 . 127.El 128.Pp 129The following parameters may be set with 130.Nm ifconfig : 131.Bl -tag -width indent 132.It Cm alias 133Establish an additional network address for this interface. 134This is sometimes useful when changing network numbers, and 135one wishes to accept packets addressed to the old interface. 136.It Cm arp 137Enable the use of the Address Resolution Protocol in mapping 138between network level addresses and link level addresses (default). 139This is currently implemented for mapping between 140.Tn DARPA 141Internet 142addresses and 10Mb/s Ethernet addresses. 143.It Fl arp 144Disable the use of the Address Resolution Protocol. 145.It Cm broadcast 146(Inet only) 147Specify the address to use to represent broadcasts to the 148network. 149The default broadcast address is the address with a host part of all 1's. 150.It Cm debug 151Enable driver dependent debugging code; usually, this turns on 152extra console error logging. 153.It Fl debug 154Disable driver dependent debugging code. 155.It Cm delete 156Remove the network address specified. 157This would be used if you incorrectly specified an alias, or it 158was no longer needed. 159If you have incorrectly set an NS address having the side effect 160of specifying the host portion, removing all NS addresses will 161allow you to respecify the host portion. 162.It Cm down 163Mark an interface ``down''. When an interface is 164marked ``down'', the system will not attempt to 165transmit messages through that interface. 166If possible, the interface will be reset to disable reception as well. 167This action does not automatically disable routes using the interface. 168.\" .It Cm ipdst 169.\" This is used to specify an Internet host who is willing to receive 170.\" ip packets encapsulating NS packets bound for a remote network. 171.\" An apparent point to point link is constructed, and 172.\" the address specified will be taken as the NS address and network 173.\" of the destination. 174.\" IP encapsulation of 175.\" .Tn CLNP 176.\" packets is done differently. 177.It Cm media Ar type 178If the driver supports the media selection system, set the media type 179of the interface to 180.Ar type . 181Some interfaces support the mutually exclusive use of one of several 182different physical media connectors. For example, a 10Mb/s Ethernet 183interface might support the use of either 184.Tn AUI 185or twisted pair connectors. Setting the media type to 186.Dq 10base5/AUI 187would change the currently active connector to the AUI port. 188Setting it to 189.Dq 10baseT/UTP 190would activate twisted pair. Refer to the interfaces' driver 191specific documentation or man page for a complete list of the 192available types. 193.It Cm mediaopt Ar opts 194If the driver supports the media selection system, set the specified 195media options on the interface. 196.Ar Opts 197is a comma delimited list of options to apply to the interface. 198Refer to the interfaces' driver specific man page for a complete 199list of available options. 200.It Fl mediaopt Ar opts 201If the driver supports the media selection system, disable the 202specified media options on the interface. 203.It Cm vlan Ar vlan_tag 204If the interface is a vlan pseudo interface, set the vlan tag value 205to 206.Ar vlan_tag . 207This value is a 16-bit number which is used to create an 802.1Q 208vlan header for packets sent from the vlan interface. Note that 209.Cm vlan 210and 211.Cm vlandev 212must both be set at the same time. 213.It Cm vlandev Ar iface 214If the interface is a vlan pseudo device, associate physical interface 215.Ar iface 216with it. Packets transmitted through the vlan interface will be 217diverted to the specified physical interface 218.Ar iface 219with 802.1Q vlan encapsulation. Packets with 802.1Q encapsulation received 220by the parent interface with the correct vlan tag will be diverted to 221the associated vlan pseudo-interface. The vlan interface is assigned a 222copy of the parent interface's flags and the parent's ethernet address. 223The 224.Cm vlandev 225and 226.Cm vlan 227must both be set at the same time. If the vlan interface already has 228a physical interface associated with it, this command will fail. To 229change the association to another physical interface, the existing 230association must be cleared first. 231.Pp 232Note: if the 233.Ar link0 234flag is set on the vlan interface, the vlan pseudo 235interface's behavior changes: the 236.Ar link0 237tells the vlan interface that the 238parent interface supports insertion and extraction of vlan tags on its 239own (usually in firmware) and that it should pass packets to and from 240the parent unaltered. 241.It Fl vlandev Ar iface 242If the driver is a vlan pseudo device, disassociate the physical interface 243.Ar iface 244from it. This breaks the link between the vlan interface and its parent, 245clears its vlan tag, flags and its link address and shuts the interface down. 246.It Cm metric Ar n 247Set the routing metric of the interface to 248.Ar n , 249default 0. 250The routing metric is used by the routing protocol 251.Pq Xr routed 8 . 252Higher metrics have the effect of making a route 253less favorable; metrics are counted as addition hops 254to the destination network or host. 255.It Cm mtu Ar n 256Set the maximum transmission unit of the interface to 257.Ar n , 258default is interface specific. 259The mtu is used to limit the size of packets that are transmitted on an 260interface. 261Not all interfaces support setting the mtu, and some interfaces have 262range restrictions. 263.It Cm netmask Ar mask 264.\" (Inet and ISO) 265(Inet only) 266Specify how much of the address to reserve for subdividing 267networks into sub-networks. 268The mask includes the network part of the local address 269and the subnet part, which is taken from the host field of the address. 270The mask can be specified as a single hexadecimal number 271with a leading 0x, with a dot-notation Internet address, 272or with a pseudo-network name listed in the network table 273.Xr networks 5 . 274The mask contains 1's for the bit positions in the 32-bit address 275which are to be used for the network and subnet parts, 276and 0's for the host part. 277The mask should contain at least the standard network portion, 278and the subnet field should be contiguous with the network 279portion. 280.\" see 281.\" Xr eon 5 . 282.\" .It Cm nsellength Ar n 283.\" .Pf ( Tn ISO 284.\" only) 285.\" This specifies a trailing number of bytes for a received 286.\" .Tn NSAP 287.\" used for local identification, the remaining leading part of which is 288.\" taken to be the 289.\" .Tn NET 290.\" (Network Entity Title). 291.\" The default value is 1, which is conformant to US 292.\" .Tn GOSIP . 293.\" When an ISO address is set in an ifconfig command, 294.\" it is really the 295.\" .Tn NSAP 296.\" which is being specified. 297.\" For example, in 298.\" .Tn US GOSIP , 299.\" 20 hex digits should be 300.\" specified in the 301.\" .Tn ISO NSAP 302.\" to be assigned to the interface. 303.\" There is some evidence that a number different from 1 may be useful 304.\" for 305.\" .Tn AFI 306.\" 37 type addresses. 307.It Cm range 308Under appletalk, set the interface to respond to a 309.Em netrange. 310of the form startnet-endnet. Appletalk uses this scheme instead of 311netmasks though 312.Bx Free 313implements it internally as a set of netmasks. 314.It Cm phase 315The argument following this specifies the version (phase) of the 316Appletalk network attached to the interface. Values of 1 or 2 are permitted. 317.It Cm link[0-2] 318Enable special processing of the link level of the interface. 319These three options are interface specific in actual effect, however, 320they are in general used to select special modes of operation. An example 321of this is to enable SLIP compression, or to select the connector type 322for some Ethernet cards. Refer to the man page for the specific driver 323for more information. 324.It Fl link[0-2] 325Disable special processing at the link level with the specified interface. 326.It Cm up 327Mark an interface 328.Dq up . 329This may be used to enable an interface after an 330.Dq ifconfig down . 331It happens automatically when setting the first address on an interface. 332If the interface was reset when previously marked down, 333the hardware will be re-initialized. 334.El 335.Pp 336.Nm Ifconfig 337displays the current configuration for a network interface 338when no optional parameters are supplied. 339If a protocol family is specified, 340.Nm 341will report only the details specific to that protocol family. 342.Pp 343If the driver does supports the media selection system, the supported 344media list will be included in the output. 345.Pp 346Optionally, the 347.Fl a 348flag may be used instead of an interface name. This flag instructs 349.Nm 350to display information about all interfaces in the system. 351The 352.Fl d 353flag limits this to interfaces that are down, and 354.Fl u 355limits this to interfaces that are up. 356.Pp 357The 358.Fl l 359flag may be used to list all available interfaces on the system, with 360no other additional information. Use of this flag is mutually exclusive 361with all other flags and commands, except for 362.Fl d 363(only list interfaces that are down) 364and 365.Fl u 366(only list interfaces that are up). 367.Pp 368Only the super-user may modify the configuration of a network interface. 369.Sh NOTES 370The media selection system is relatively new and only some drivers support 371it (or have need for it). 372.Sh DIAGNOSTICS 373Messages indicating the specified interface does not exist, the 374requested address is unknown, or the user is not privileged and 375tried to alter an interface's configuration. 376.Sh SEE ALSO 377.Xr netstat 1 , 378.Xr netintro 4 , 379.Xr rc 8 , 380.Xr routed 8 381.\" .Xr eon 5 382.Sh HISTORY 383The 384.Nm 385command appeared in 386.Bx 4.2 . 387