IFCONFIG(8) System Manager's Manual IFCONFIG(8) NAME ifconfig -- configure network interface parameters SYNOPSIS ifconfig [-L] [-m] interface [create] [address_family] [address [dest_address]] [parameters] ifconfig interface destroy ifconfig -a [-L] [-d] [-m] [-u] [address_family] ifconfig -l [-d] [-u] [address_family] ifconfig [-L] [-d] [-m] [-u] [-C] DESCRIPTION Ifconfig is used to assign an address to a network interface and/or config- ure network interface parameters. 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. The following options are available: address For the DARPA-Internet family, the address is either a host name present in the host name data base, hosts(5), or a DARPA Internet address expressed in the Internet standard "dot notation". 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 192.168.0.1/16. For "inet6" family, it is also possible to specify the prefix length using the slash notation, like ::1/128. See the prefixlen parameter below for more information. The link-level ("link") address is specified as a series of colon- separated hex digits. This can be used to e.g. set a new MAC ad- dress on an ethernet interface, though the mechanism used is not ethernet-specific. 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. address_family Specify the address family which affects interpretation of the re- maining parameters. Since an interface can receive transmissions in differing protocols with different naming schemes, specifying the address family is recommended. The address or protocol fami- lies currently supported are "inet", "inet6", "atalk", "ipx", and "link". The default is "inet". "ether" and "lladdr" are synonyms for "link". dest_address Specify the address of the correspondent on the other end of a point to point link. interface This parameter is a string of the form "name unit", for example, "ed0". The following parameters may be set with ifconfig: add Another name for the alias parameter. Introduced for compatibility with BSD/OS. 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 inter- face, a non-conflicting netmask must be given. Usually 0xffffffff is most appropriate. -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 speci- fying the host portion, removing all NS addresses will allow you to respecify the host portion. anycast (Inet6 only.) Specify that the address configured is an anycast address. Based on the current specification, only routers may con- figure anycast addresses. Anycast address will not be used as source address of any of outgoing IPv6 packets. arp Enable the use of the Address Resolution Protocol (arp(4)) in map- ping between network level addresses and link level addresses (de- fault). This is currently implemented for mapping between DARPA Internet addresses and IEEE 802 48-bit MAC addresses (Ethernet, FDDI, and Token Ring addresses). -arp Disable the use of the Address Resolution Protocol (arp(4)). 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. debug Enable driver dependent debugging code; usually, this turns on ex- tra console error logging. -debug Disable driver dependent debugging code. delete Another name for the -alias parameter. down Mark an interface "down". When an interface is marked "down", the system will not attempt to transmit messages through that inter- face. If possible, the interface will be reset to disable recep- tion as well. This action does not automatically disable routes using the interface. media type If the driver supports the media selection system, set the media type of the interface to type. Some interfaces support the mutu- ally exclusive use of one of several different physical media con- nectors. For example, a 10Mb/s Ethernet interface might support the use of either AUI or twisted pair connectors. Setting the me- dia type to "10base5/AUI" would change the currently active connec- tor to the AUI port. Setting it to "10baseT/UTP" would activate twisted pair. Refer to the interfaces' driver specific documenta- tion or man page for a complete list of the available types. mediaopt opts If the driver supports the media selection system, set the speci- fied media options on the interface. The 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 avail- able options. -mediaopt opts If the driver supports the media selection system, disable the specified media options on the interface. tunnel src_addr dest_addr (IP tunnel devices only.) Configure the physical source and desti- nation address for IP tunnel interfaces (gif(4)). The arguments src_addr and dest_addr are interpreted as the outer source/destina- tion for the encapsulating IPv4/IPv6 header. deletetunnel Unconfigure the physical source and destination address for IP tun- nel interfaces previously configured with tunnel. create Create the specified network pseudo-device. If the interface is given without a unit number, try to create a new device with an ar- bitrary unit number. If creation of an arbitrary device is suc- cessful, the new device name is printed to standard output. destroy Destroy the specified network pseudo-device. plumb Another name for the create parameter. Included for Solaris com- patibility. unplumb Another name for the destroy parameter. Included for Solaris com- patibility. vlan vlan_tag If the interface is a vlan pseudo interface, set the vlan tag value to 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 vlan and vlandev must both be set at the same time. vlandev iface If the interface is a vlan pseudo device, associate physical inter- face iface with it. Packets transmitted through the vlan interface will be diverted to the specified physical interface iface with 802.1Q vlan encapsulation. Packets with 802.1Q encapsulation re- ceived by the parent interface with the correct vlan tag will be diverted to the associated vlan pseudo-interface. The vlan inter- face is assigned a copy of the parent interface's flags and the parent's ethernet address. The vlandev and vlan must both be set at the same time. If the vlan interface already has a physical in- terface associated with it, this command will fail. To change the association to another physical interface, the existing association must be cleared first. Note: if the link0 flag is set on the vlan interface, the vlan pseudo interface's behavior changes: the link0 tells the vlan in- terface 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. -vlandev iface If the driver is a vlan pseudo device, disassociate the physical interface iface from it. This breaks the link between the vlan in- terface and its parent, clears its vlan tag, flags and its link ad- dress and shuts the interface down. metric n Set the routing metric of the interface to n, default 0. The rout- ing metric is used by the routing protocol (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. mtu n Set the maximum transmission unit of the interface to 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. netmask mask (Inet only.) Specify how much of the address to reserve for subdi- viding 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 sin- gle hexadecimal number with a leading `0x', with a dot-notation In- ternet address, or with a pseudo-network name listed in the network table 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 con- tiguous with the network portion. The netmask can also be specified in CIDR notation after the ad- dress. See the address option above for more information. prefixlen len (Inet6 only.) Specify that len bits are reserved for subdividing networks into sub-networks. The len must be integer, and for syn- tactical 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. The prefix can also be specified using the slash notation after the address. See the address option above for more information. range netrange Under appletalk, set the interface to respond to a netrange of the form startnet-endnet. Appletalk uses this scheme instead of net- masks though FreeBSD implements it internally as a set of netmasks. remove Another name for the -alias parameter. Introduced for compatibil- ity with BSD/OS. phase The argument following this specifies the version (phase) of the Appletalk network attached to the interface. Values of 1 or 2 are permitted. link[0-2] Enable special processing of the link level of the interface. These three options are interface specific in actual effect, how- ever, they are in general used to select special modes of opera- tion. An example of this is to enable SLIP compression, or to se- lect the connector type for some Ethernet cards. Refer to the man page for the specific driver for more information. -link[0-2] Disable special processing at the link level with the specified in- terface. up Mark an interface "up". This may be used to enable an interface after an "ifconfig 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. ssid ssid For IEEE 802.11 wireless interfaces, set the desired Service Set Identifier (aka network name). The SSID is a string up to 32 char- acters in length and may be specified as either a normal string or in hexadecimal when proceeded by `0x'. Additionally, the SSID may be cleared by setting it to `-'. nwid ssid Another name for the ssid parameter. Included for NetBSD compati- bility. stationname name For IEEE 802.11 wireless interfaces, set the name of this station. It appears that the station name is not really part of the IEEE 802.11 protocol though all interfaces seem to support it. As such it only seems to be meaningful to identical or virtually identical equipment. Setting the station name is identical in syntax to set- ting the SSID. station name Another name for the stationname parameter. Included for BSD/OS compatibility. channel number For IEEE 802.11 wireless interfaces, set the desired channel. Channels range from 1 to 14, but the exact selection available de- pends on the region your adaptor was manufactured for. Setting the channel to 0 will give you the default for your adaptor. Many adaptors ignore this setting unless you are in ad-hoc mode. authmode mode For IEEE 802.11 wireless interfaces, set the desired authentication mode in infrastructure mode. Not all adaptors support all modes. The set of valid modes is "none", "open", and "shared". Modes are case insensitive. powersave For IEEE 802.11 wireless interfaces, enable powersave mode. -powersave For IEEE 802.11 wireless interfaces, disable powersave mode. powersavesleep sleep For IEEE 802.11 wireless interfaces, set the desired max powersave sleep time in milliseconds. wepmode mode For IEEE 802.11 wireless interfaces, set the desired WEP mode. Not all adaptors support all modes. The set of valid modes is "off", "on", and "mixed". "Mixed" mode explicitly tells the adaptor to allow association with access points which allow both encrypted and unencrypted traffic. On these adaptors, "on" means that the access point must only allow encrypted connections. On other adaptors, "on" is generally another name for "mixed". Modes are case insen- sitive. weptxkey index For IEEE 802.11 wireless interfaces, set the WEP key to be used for transmission. wepkey key|index:key For IEEE 802.11 wireless interfaces, set the selected WEP key. If an index is not given, key 1 is set. A WEP key will be either 5 or 13 characters (40 or 104 bits) depending of the local network and the capabilities of the adaptor. It may be specified either as a plain string or as a string of hexadecimal digits proceeded by `0x'. A key may be cleared by setting it to `-'. If WEP is sup- ported then there are at least four keys. Some adaptors support more than four keys. If that is the case, then the first four keys (1-4) will be the standard temporary keys and any others will be adaptor specific keys such as permanent keys stored in NVRAM. wep Another way of saying wepmode on. Included for BSD/OS compatibil- ity. -wep Another way of saying wepmode off. Included for BSD/OS compatibil- ity. nwkey key Another way of saying: "wepmode on weptxkey 1 wepkey 1:key wepkey 2:- wepkey 3:- wepkey 4:-". Included for NetBSD compatibility. nwkey n:k1,k2,k3,k4 Another way of saying "wepmode on weptxkey n wepkey 1:k1 wepkey 2:k2 wepkey 3:k3 wepkey 4:k4". Included for NetBSD compatibility. -nwkey Another way of saying wepmode off. Included for NetBSD compatibility. Ifconfig displays the current configuration for a network interface when no optional parameters are supplied. If a protocol family is specified, ifconfig will report only the details specific to that protocol family. If the driver does supports the media selection system, the supported media list will be included in the output. If the -m flag is passed before an interface name, ifconfig will display all of the supported media for the specified interface. If -L flag is sup- plied, address lifetime is displayed for IPv6 addresses, as time offset string. Optionally, the -a flag may be used instead of an interface name. This flag instructs ifconfig to display information about all interfaces in the system. The -d flag limits this to interfaces that are down, and -u limits this to interfaces that are up. When no arguments are given, -a is im- plied. The -l flag may be used to list all available interfaces on the system, with no other additional information. Use of this flag is mutually exclu- sive with all other flags and commands, except for -d (only list interfaces that are down) and -u (only list interfaces that are up). The -C flag may be used to list all of the interface cloners available on the system, with no additional information. Use of this flag is mutually exclusive with all other flags and commands. Only the super-user may modify the configuration of a network interface. NOTES The media selection system is relatively new and only some drivers support it (or have need for it). 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 in- terface's configuration. BUGS IPv6 link-local addresses are required for several basic communication be- tween IPv6 node. If they are deleted by ifconfig manually, the kernel might show very strange behavior. So, such manual deletions are strongly discouraged. SEE ALSO netstat(1), netintro(4), rc(8), routed(8) HISTORY The ifconfig command appeared in 4.2BSD. FreeBSD 4.6 July 2, 2001 IFCONFIG(8)
NAME | SYNOPSIS | DESCRIPTION | NOTES | DIAGNOSTICS | BUGS | SEE ALSO | HISTORY
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