IFCONFIG(8)						      System Manager's Manual						       IFCONFIG(8)

NAME

       ifconfig - configure network interface parameters

SYOPNSIS

       /sbin/ifconfig interface address_family [ address [ dest_address ] ] [ parameters ]
       /sbin/ifconfig interface [ protocol_family ]

DESCRIPTION

       Ifconfig  is used to assign an address to a network interface and/or configure 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 interface parameter is a string of the form ``name unit'', e.g. ``en0''.

       Since  an interface may receive transmissions in differing protocols, each of which may require separate naming schemes, it is necessary to
       specify the address_family, which may change the interpretation of the remaining parameters.  The address families currently supported  are
       ``inet'' and ``ns''.

       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''.  For the Xerox Network Systems(tm) family, addresses are net:a.b.c.d.e.f, where net is
       the  assigned  network  number  (in decimal), and each of the six bytes of the host number, a through f, are specified in hexadecimal.  The
       host number may be omitted on 10Mb/s Ethernet interfaces, which use the hardware physical address, and on interfaces other than the first.

       The following parameters may be set with ifconfig:

       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.

       down	      Mark an interface ``down''.  When an interface is marked ``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.

       trailers       Request the use of a ``trailer'' link level encapsulation when sending (default).  If a network interface supports trailers,
		      the  system  will,  when	possible, encapsulate outgoing messages in a manner which minimizes the number of memory to memory
		      copy operations performed by the receiver.  On networks that support the Address	Resolution  Protocol  (see  arp(4P);  cur-
		      rently,  only  10  Mb/s  Ethernet),  this flag indicates that the system should request that other systems use trailers when
		      sending to this host.  Similarly, trailer encapsulations will be sent to other hosts that have  made  such  requests.   Cur-
		      rently used by Internet protocols only.

       -trailers      Disable the use of a ``trailer'' link level encapsulation.

       arp	      Enable  the  use	of  the  Address  Resolution  Protocol in mapping between network level addresses and link level addresses
		      (default).  This is currently implemented for mapping between DARPA Internet addresses and 10Mb/s Ethernet addresses.

       -arp	      Disable the use of the Address Resolution Protocol.

       metric n       Set the routing metric of the interface to n, default 0.	The routing 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.

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

       -debug	      Disable driver dependent debugging code.

       netmask mask   (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 0x, with a dot-notation Internet 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  net-
		      work portion, and the subnet field should be contiguous with the network portion.

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

       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.

       ipdst	      (NS only) This is used to specify an Internet host who is willing to receive ip packets encapsulating NS packets bound for a
		      remote  network.	 In  this case, an apparent point to point link is constructed, and the address specified will be taken as
		      the NS address and network of the destinee.

       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.

       Only the super-user may modify the configuration of a network interface.

DIAGNOSTICS

       Messages  indicating  the  specified  interface does not exit, the requested address is unknown, or the user is not privileged and tried to
       alter an interface's configuration.

SEE ALSO

       netstat(1), intro(4N), rc(8)

4.2 Berkeley Distribution					 November 16, 1996						       IFCONFIG(8)