.\" Copyright (c) 1983, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgment: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" From: @(#)ifconfig.8 8.3 (Berkeley) 1/5/94 .\" $FreeBSD: src/sbin/ifconfig/ifconfig.8,v 188.8.131.52 2001/08/23 06:35:38 yar Exp $ .\" .Dd July 2, 2001 .Dt IFCONFIG 8 .Os .Sh NAME .Nm ifconfig .Nd configure network interface parameters .Sh SYNOPSIS .Nm .Op Fl L .Op Fl m .Ar interface .Op Cm create .Op Ar address_family .Oo .Ar address Ns Op Cm / Ns Ar prefixlength .Op Ar dest_address .Oc .Op Ar parameters .Nm .Ar interface .Cm destroy .Nm .Fl a .Op Fl L .Op Fl d .Op Fl m .Op Fl u .Op Ar address_family .Nm .Fl l .Op Fl d .Op Fl u .Op Ar address_family .Nm .Op Fl L .Op Fl d .Op Fl m .Op Fl u .Sh DESCRIPTION .Nm Ifconfig is used to assign an address to a network interface and/or configure network interface parameters. .Nm Ifconfig must be used at boot time to define the network address of each interface present on a machine; it may also be used at a later time to redefine an interface's address or other operating parameters. .Pp The following options are available: .Bl -tag -width indent .It Ar address For the .Tn DARPA Ns -Internet family, the address is either a host name present in the host name data base, .Xr hosts 5 , or a .Tn DARPA Internet address expressed in the Internet standard .Dq dot notation . .Pp It is also possible to use the CIDR notation (also known as the slash notation) to include the netmask. That is, one can specify an address like .Li 192.168.0.1/16 . .\" For the Xerox Network Systems(tm) family, .\" addresses are .\" .Ar net:a.b.c.d.e.f , .\" where .\" .Ar net .\" is the assigned network number (in decimal), .\" and each of the six bytes of the host number, .\" .Ar a .\" through .\" .Ar f , .\" are specified in hexadecimal. .\" The host number may be omitted on IEEE 802 protocol .\" (Ethernet, FDDI, and Token Ring) interfaces, .\" which use the hardware physical address, .\" and on interfaces other than the first. .\" For the .\" .Tn ISO .\" family, addresses are specified as a long hexadecimal string, .\" as in the Xerox family. .\" However, two consecutive dots imply a zero .\" byte, and the dots are optional, if the user wishes to (carefully) .\" count out long strings of digits in network byte order. .It Ar address_family Specify the address family which affects interpretation of the remaining parameters. Since an interface can receive transmissions in differing protocols with different naming schemes, specifying the address family is recommended. The address or protocol families currently supported are .Dq inet , .Dq inet6 , .\" and .\" .Dq ns . .It Ar dest_address Specify the address of the correspondent on the other end of a point to point link. .It Ar interface This parameter is a string of the form .Dq name unit , for example, .Dq Li en0 . .El .Pp The following parameters may be set with .Nm : .Bl -tag -width indent .It Cm add Another name for the .Cm alias parameter. Introduced for compatibility with .Bsx . .It Cm alias Establish an additional network address for this interface. This is sometimes useful when changing network numbers, and one wishes to accept packets addressed to the old interface. If the address is on the same subnet as the first network address for this interface, a netmask of .Li 0xffffffff has to be specified. .It Fl alias Remove the network address specified. This would be used if you incorrectly specified an alias, or it was no longer needed. If you have incorrectly set an NS address having the side effect of specifying the host portion, removing all NS addresses will allow you to respecify the host portion. .It Cm anycast (Inet6 only.) Specify that the address configured is an anycast address. Based on the current specification, only routers may configure anycast addresses. Anycast address will not be used as source address of any of outgoing IPv6 packets. .It Cm arp Enable the use of the Address Resolution Protocol .Pq Xr arp 4 in mapping between network level addresses and link level addresses (default). This is currently implemented for mapping between .Tn DARPA Internet addresses and .Tn IEEE 802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses). .It Fl arp Disable the use of the Address Resolution Protocol .Pq Xr arp 4 . .It Cm broadcast (Inet only.) Specify the address to use to represent broadcasts to the network. The default broadcast address is the address with a host part of all 1's. .It Cm debug Enable driver dependent debugging code; usually, this turns on extra console error logging. .It Fl debug Disable driver dependent debugging code. .It Cm delete Another name for the .Fl alias parameter. .It Cm down Mark an interface .Dq down . When an interface is marked .Dq down , the system will not attempt to transmit messages through that interface. If possible, the interface will be reset to disable reception as well. This action does not automatically disable routes using the interface. .It Cm ether Another name for the .Cm lladdr parameter. .\" .It Cm ipdst .\" This is used to specify an Internet host who is willing to receive .\" ip packets encapsulating NS packets bound for a remote network. .\" An apparent point to point link is constructed, and .\" the address specified will be taken as the NS address and network .\" of the destination. .\" IP encapsulation of .\" .Tn CLNP .\" packets is done differently. .It Cm lladdr Ar addr Set the link-level address on an interface. This can be used to e.g. set a new MAC address on an ethernet interface, though the mechanism used is not ethernet-specific. The address .Ar addr is specified as a series of colon-separated hex digits. If the interface is already up when this option is used, it will be briefly brought down and then brought back up again in order to ensure that the receive filter in the underlying ethernet hardware is properly reprogrammed. .It Cm media Ar type If the driver supports the media selection system, set the media type of the interface to .Ar type . Some interfaces support the mutually exclusive use of one of several different physical media connectors. For example, a 10Mb/s Ethernet interface might support the use of either .Tn AUI or twisted pair connectors. Setting the media type to .Dq 10base5/AUI would change the currently active connector to the AUI port. Setting it to .Dq 10baseT/UTP would activate twisted pair. Refer to the interfaces' driver specific documentation or man page for a complete list of the available types. .It Cm mediaopt Ar opts If the driver supports the media selection system, set the specified media options on the interface. The .Ar opts argument is a comma delimited list of options to apply to the interface. Refer to the interfaces' driver specific man page for a complete list of available options. .It Fl mediaopt Ar opts If the driver supports the media selection system, disable the specified media options on the interface. .It Cm tunnel Ar src_addr dest_addr (IP tunnel devices only.) Configure the physical source and destination address for IP tunnel interfaces .Pq Xr gif 4 . The arguments .Ar src_addr and .Ar dest_addr are interpreted as the outer source/destination for the encapsulating IPv4/IPv6 header. .It Cm deletetunnel Unconfigure the physical source and destination address for IP tunnel interfaces previously configured with .Cm tunnel . .It Cm create Create the specified network pseudo-device. If the interface is given without a unit number, try to create a new device with an arbitrary unit number. If creation of an arbitrary device is successful, the new device name is printed to standard output. .It Cm destroy Destroy the specified network pseudo-device. .It Cm plumb Another name for the .Cm create parameter. Included for .Tn Solaris compatibility. .It Cm unplumb Another name for the .Cm destroy parameter. Included for .Tn Solaris compatibility. .It Cm vlan Ar vlan_tag If the interface is a vlan pseudo interface, set the vlan tag value to .Ar vlan_tag . This value is a 16-bit number which is used to create an 802.1Q vlan header for packets sent from the vlan interface. Note that .Cm vlan and .Cm vlandev must both be set at the same time. .It Cm vlandev Ar iface If the interface is a vlan pseudo device, associate physical interface .Ar iface with it. Packets transmitted through the vlan interface will be diverted to the specified physical interface .Ar iface with 802.1Q vlan encapsulation. Packets with 802.1Q encapsulation received by the parent interface with the correct vlan tag will be diverted to the associated vlan pseudo-interface. The vlan interface is assigned a copy of the parent interface's flags and the parent's ethernet address. The .Cm vlandev and .Cm vlan must both be set at the same time. If the vlan interface already has a physical interface associated with it, this command will fail. To change the association to another physical interface, the existing association must be cleared first. .Pp Note: if the hardware tagging capability is set on the vlan interface, the vlan pseudo interface's behavior changes: the vlan interface recognizes that the parent interface supports insertion and extraction of vlan tags on its own (usually in firmware) and that it should pass packets to and from the parent unaltered. .It Fl vlandev Ar iface If the driver is a vlan pseudo device, disassociate the physical interface .Ar iface from it. This breaks the link between the vlan interface and its parent, clears its vlan tag, flags and its link address and shuts the interface down. .It Cm metric Ar n Set the routing metric of the interface to .Ar n , default 0. The routing metric is used by the routing protocol .Pq Xr routed 8 . Higher metrics have the effect of making a route less favorable; metrics are counted as addition hops to the destination network or host. .It Cm mtu Ar n Set the maximum transmission unit of the interface to .Ar n , default is interface specific. The MTU is used to limit the size of packets that are transmitted on an interface. Not all interfaces support setting the MTU, and some interfaces have range restrictions. .It Cm netmask Ar mask .\" (Inet and ISO.) (Inet only.) Specify how much of the address to reserve for subdividing networks into sub-networks. The mask includes the network part of the local address and the subnet part, which is taken from the host field of the address. The mask can be specified as a single hexadecimal number with a leading .Ql 0x , with a dot-notation Internet address, or with a pseudo-network name listed in the network table .Xr networks 5 . The mask contains 1's for the bit positions in the 32-bit address which are to be used for the network and subnet parts, and 0's for the host part. The mask should contain at least the standard network portion, and the subnet field should be contiguous with the network portion. .Pp The netmask can also be specified in CIDR notation after the address. See the .Ar address option above for more information. .It Cm prefixlen Ar len (Inet6 only.) Specify that .Ar len bits are reserved for subdividing networks into sub-networks. The .Ar len must be integer, and for syntactical reason it must be between 0 to 128. It is almost always 64 under the current IPv6 assignment rule. If the parameter is omitted, 64 is used. .\" see .\" Xr eon 5 . .\" .It Cm nsellength Ar n .\" .Pf ( Tn ISO .\" only) .\" This specifies a trailing number of bytes for a received .\" .Tn NSAP .\" used for local identification, the remaining leading part of which is .\" taken to be the .\" .Tn NET .\" (Network Entity Title). .\" The default value is 1, which is conformant to US .\" .Tn GOSIP . .\" When an ISO address is set in an ifconfig command, .\" it is really the .\" .Tn NSAP .\" which is being specified. .\" For example, in .\" .Tn US GOSIP , .\" 20 hex digits should be .\" specified in the .\" .Tn ISO NSAP .\" to be assigned to the interface. .\" There is some evidence that a number different from 1 may be useful .\" for .\" .Tn AFI .\" 37 type addresses. .It Cm remove Another name for the .Fl alias parameter. Introduced for compatibility with .Bsx . .Sm off .It Cm link Op Cm 0 No - Cm 2 .Sm on Enable special processing of the link level of the interface. These three options are interface specific in actual effect, however, they are in general used to select special modes of operation. An example of this is to enable SLIP compression, or to select the connector type for some Ethernet cards. Refer to the man page for the specific driver for more information. .Sm off .It Fl link Op Cm 0 No - Cm 2 .Sm on Disable special processing at the link level with the specified interface. .It Cm up Mark an interface .Dq up . This may be used to enable an interface after an .Dq Nm Cm down . It happens automatically when setting the first address on an interface. If the interface was reset when previously marked down, the hardware will be re-initialized. .El .Pp .Nm Ifconfig displays the current configuration for a network interface when no optional parameters are supplied. If a protocol family is specified, .Nm will report only the details specific to that protocol family. .Pp If the driver does supports the media selection system, the supported media list will be included in the output. .Pp If the .Fl m flag is passed before an interface name, .Nm will display all of the supported media for the specified interface. If .Fl L flag is supplied, address lifetime is displayed for IPv6 addresses, as time offset string. .Pp Optionally, the .Fl a flag may be used instead of an interface name. This flag instructs .Nm to display information about all interfaces in the system. The .Fl d flag limits this to interfaces that are down, and .Fl u limits this to interfaces that are up. When no arguments are given, .Fl a is implied. .Pp The .Fl l flag may be used to list all available interfaces on the system, with no other additional information. Use of this flag is mutually exclusive with all other flags and commands, except for .Fl d (only list interfaces that are down) and .Fl u (only list interfaces that are up). .Pp Only the super-user may modify the configuration of a network interface. .Sh NOTES The media selection system is relatively new and only some drivers support it (or have need for it). .Sh DIAGNOSTICS Messages indicating the specified interface does not exist, the requested address is unknown, or the user is not privileged and tried to alter an interface's configuration. .Sh BUGS IPv6 link-local addresses are required for several basic communication between IPv6 node. If they are deleted by .Nm manually, the kernel might show very strange behavior. So, such manual deletions are strongly discouraged. .Sh SEE ALSO .Xr netstat 1 , .Xr netintro 4 , .\" .Xr eon 5 , .Xr rc 8 , .Xr routed 8 .Sh HISTORY The .Nm command appeared in .Bx 4.2 .