IFCONFIG(8C)                         BSD                          IFCONFIG(8C)



NAME
     ifconfig - configure network interface parameters

SYNOPSIS
     /etc/ifconfig interface [ address_family ] [ address [ dest_address ] ] [
     parameters ]
     /etc/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, for example, eth0.

     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 only address family currently supported by Apollo is
     inet .

     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".

PARAMETERS
     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); currently, only 10 MB 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.  Currently 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 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(8c)).  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 network 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.

     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
     intro(4N), netstat(1), rc(8);
     Configuring and Managing TCP/IP.