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ifconfig(1M)							  ifconfig(1M)

NAME    [Toc]    [Back]

     ifconfig -	configure network interface parameters

SYNOPSIS    [Toc]    [Back]

     /usr/etc/ifconfig [ -v ] interface	address_family [ address [ dest_address	] ]
	  [ parameters ]
     /usr/etc/ifconfig interface [ protocol_family ]
     /usr/etc/ifconfig [ -v ] -a

DESCRIPTION    [Toc]    [Back]

     ifconfig is used to assign	an address to a	network	interface and/or
     configure network interface parameters.  ifconfig is invoked at boot time
     from /etc/init.d/network to define	the network address of each interface
     present on	a machine; you can also	use it once the	system is up to
     redefine an interface's address or	other operating	parameters.  The
     interface parameter is a string of	the form ``name	unit'',	for example,
     enp0.  Using the -a option	shows status for all interfaces	on the

     If	specified, the -v option causes	additional information about specified
     interfaces	to be displayed, including speed.

     Since an interface	can receive transmissions in differing protocols, each
     of	which may require separate naming schemes, it is necessary to specify
     the address_family, which can change the interpretation of	the remaining
     parameters.  Currently, just the ``inet'' address family is supported.

     For the Internet family, the address is either an Internet	address
     expressed in the Internet standard	``dot notation'' (see inet(3N)), or a
     hostname present in the hosts(4) file, /etc/hosts.	 (Other	hosts
     databases,	such as	named and NIS, are ignored.)

     Only the superuser	can modify the configuration of	a network interface.

     The following parameters can be set with ifconfig:

     up		    Mark an interface up.  This	can 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 is reinitialized.

     down	    Mark an interface down.  When an interface is marked down,
		    the	system does not	attempt	to transmit messages through
		    that interface.  If	possible, the interface	is reset to
		    disable reception as well.	This action does not
		    automatically disable routes using the interface.

     arp	    Enable the use of the Address Resolution Protocol in
		    mapping between network level addresses and	link level
		    addresses (default).  It is	used by	a variety of data link
		    network interfaces such as Ethernet.

									Page 1

ifconfig(1M)							  ifconfig(1M)

     -arp	    Disable the	use of the Address Resolution Protocol.

     alias addr	    Establish an additional network address for	this
		    interface.	This can be useful in permitting a single
		    physical interface to accept packets addressed to several
		    different addresses	such as	when you are changing network
		    numbers and	you wish to accept packets addressed to	the
		    old	interface.  Another case is when you'd like to have
		    multiple addresses assigned	to a single network interface.
		    The	broadcast and netmask options can also be used in
		    conjunction	with the alias option.	When using aliases you
		    may	have to	change the configuration of routed, especially
		    if aliases are on different	networks than the primary
		    address.  Aliases are added	as host	entries	in the routing
		    tables for routed.	See routed(1M) for more	information on

     -alias|delete addr
		    Deletes a previously added alias.

     metric n	    Set	the routing metric of the interface to n, default 0.
		    The	routing	metric is used by the routing protocol
		    (routed).  Higher metrics have the effect of making	a
		    route less favorable; metrics are counted as addition hops
		    to the destination network or host.

     netmask mask   Specify how	much of	the address to reserve for subdividing
		    networks into subnetworks.	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
		    0x,	with a dot-notation Internet address, or with a
		    pseudo-network name	listed in the network table
		    networks(4).  The mask contains 1's	for the	bit positions
		    in the 32-bit address that 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

     mtu n	    Specify device maximum transmission	unit value.  This may
		    not	be supported on	all devices.  Currently, this may be
		    used to lower ethernet MTU's below 1500 bytes to
		    interoperate with buggy adapters and network hardware.

     broadcast addr 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.

     dest_addr	    Specify the	address	of the correspondent on	the other end
		    of a point-to-point	link.

									Page 2

ifconfig(1M)							  ifconfig(1M)

     debug	    Enable driver-dependent debugging code; usually, this
		    turns on extra console error logging.

     -debug	    Disable driver-dependent debugging code.

     highbw	    Flag an interface as being a high-bandwidth	interface.
		    This acts as a hint	which allows upper layer protocols to
		    adjust their behaviour to optimise performance (e.g. TCP
		    will be less aggressive with ACKing).

     -highbw	    Remove the high-bandwidth flag from	an interface.

     link{0,1,2}    Enable driver-specific feature 0-2.

     -link{0,1,2}   Disable driver-specific feature 0-2.

     primary	    This parameter makes the specified interface the primary
		    interface for networking.  In cases	where no interface or
		    interface address is specified by an application, the
		    'primary' interface	will be	preferred.

     rspace value   Specifies the default receive space	used by	TCP when
		    communicating over the interface.  Use a value of 0	to
		    clear this parameter and use the system-wide default.

     sspace value   Specifies the default send space used by TCP when
		    communicating over the interface.  Use a value of 0	to
		    clear this parameter and use the system-wide default.

     ifconfig displays the current configuration for a network interface when
     no	optional parameters are	supplied.  If a	protocol family	is specified,
     ifconfig reports only the details specific	to that	protocol family.

NOTES    [Toc]    [Back]

     Network interfaces	on Silicon Graphics systems can	only receive and not
     send packets that use ``trailer'' link-level encapsulation.  Therefore,
     ifconfig does not accept the trailers parameter.

     For 100baseTX interfaces, such as 'ef', LINK0 being set indicates that
     the device	is operating at	full-duplex.  It is not	currently possible to
     force full- or half-duplex	by setting or clearing this flag.

     Currently options such as 'metric'	are not	handled	for IP aliases;
     adjusting the metric will affect only the primary address.	 'broadcast'
     and 'netmask' are the only	options	currently known	to work	properly with
     IP	aliases.

DIAGNOSTICS    [Toc]    [Back]

     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.

									Page 3

ifconfig(1M)							  ifconfig(1M)

FILES    [Toc]    [Back]

     /etc/hosts			      host-address database
     /etc/config/ifconfig-?.options   site-specific options (1 file per
     /etc/config/ipaliases.options    interface-specific ip alias addresses

SEE ALSO    [Toc]    [Back]

     netstat(1), network(1M).

									PPPPaaaaggggeeee 4444
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