ifconfig(1M)                                                   ifconfig(1M)

NAME
     ifconfig - configure network interface parameters

SYNOPSIS

     ifconfig interface address_family [address [dest_address]] [parameters]

     ifconfig interface [address_family]

DESCRIPTION
     The first form of the ifconfig command assigns an address to a network
     interface and/or configures network interface parameters.  ifconfig
     must be used at boot time to define the network address of each
     interface present on a machine.  It can also be used at other times to
     redefine an interface's address or other operating parameters.

     The second form of the command, without address_family, displays the
     current configuration for interface.  If address_family is also
     specified, ifconfig reports only the details specific to that address
     family.

     Only a user with appropriate privileges can modify the configuration
     of a network interface.  All users can run the second form of the
     command.

   Arguments
     ifconfig recognizes the following arguments:

          address         Either a host name present in the host name
                          database (see hosts(4)), or a DARPA Internet
                          address expressed in Internet standard dot
                          notation (see inet(3N)).  The host number can be
                          omitted on 10MB/second Ethernet interfaces (which
                          use the hardware physical address), and on
                          interfaces other than the first.

          address_family  Name of protocol on which naming scheme is based.
                          An interface can receive transmissions in
                          differing protocols, each of which may require
                          separate naming schemes.  Therefore, it is
                          necessary to specify the address_family, which
                          may affect interpretation of the remaining
                          parameters on the command line.  The only address
                          family currently supported is inet (DARPA-
                          Internet family).

          dest_address    Address of destination system.  Consists of
                          either a host name present in the host name
                          database (see hosts(4)), or a DARPA Internet
                          address expressed in Internet standard dot
                          notation (see inet(3N)).

          interface       A string of the form nameunit, such as lan0.
                          (See the LAN Card Numbering subsection.)

          parameters      One or more of the following operating
                          parameters:

                          up             Mark an interface "up". Enables
                                         interface after an ifconfig down.
                                         Occurs automatically when setting
                                         the address on an interface.
                                         Setting this flag has no effect if
                                         the hardware is "down".

                          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.

                          broadcast      (Inet only) Specify the address
                                         that represents 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.  This usually turns on extra
                                         console error logging.

                          -debug         Disable driver-dependent debugging
                                         code.

                          ipdst          (NS only) This is used to specify
                                         an Internet host that 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 is taken as the NS
                                         address and network of the
                                         destination.

                          metric n       Set the routing metric of the
                                         interface to n.  The default is 0.
                                         The routing metric is used by the
                                         routing protocol (see gated(1m)).
                                         Higher metrics have the effect of
                                         making a route less favorable;
                                         metrics are counted as additional
                                         hops to the destination network or
                                         host.

                          netmask mask   (Inet only) Specify how much of
                                         the address to reserve for
                                         subdividing networks into sub-
                                         networks or aggregating networks
                                         into supernets.  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 (see
                                         networks(4)).  For subdividing
                                         networks into sub-networks, mask
                                         must include the network part of
                                         the local address, and the subnet
                                         part which is taken from the host
                                         field of the address.  mask must
                                         contain 1's in the bit positions
                                         in the 32-bit address that are to
                                         be used for the network and subnet
                                         parts, and 0's in the host part.
                                         The 1's in the mask must be
                                         contiguous starting from the
                                         leftmost bit position in the 32-
                                         bit field.  mask must contain at
                                         least the standard network
                                         portion, and the subnet field must
                                         be contiguous with the network
                                         portion.  The subnet field must
                                         contain at least 2 bits. The
                                         subnet part after performing a
                                         bit-wise AND operation between the
                                         address and the mask must not
                                         contain all 0's or all 1's.  For
                                         aggregating networks into
                                         supernets, mask must only include
                                         a portion of the network part.
                                         mask must contain contiguous 1's
                                         in the bit positions starting from
                                         the leftmost bit of the 32-bit
                                         field.

                          trailers       Request the use of a "trailer"
                                         link-level encapsulation when
                                         sending.  If a network interface
                                         supports trailers, the system
                                         will, when possible, encapsulate
                                         outgoing messages in a manner that
                                         minimizes the number of memory-
                                         to-memory copy operations
                                         performed by the receiver.  On
                                         networks that support the Address
                                         Resolution Protocol, 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.  See
                                         WARNINGS section.

                          -trailers      Disable the use of a "trailer"
                                         link-level encapsulation
                                         (default).
   LAN Card Numbering
     The name of an interface associated with a LAN card is lan, and its
     unitnumber is determined as follows.  The LAN card installed first in
     the system is given interface unit number 0; the next LAN card
     installed is given interface unit number 1; and so on. When there are
     two or more LAN cards installed at the same time, interface unit
     numbers are assigned according to card positions in the  backplane:
     the LAN card that appears "first" in the backplane is given the
     interface unit number N; the next LAN card in the backplane is given
     the number N+1.

     The lanscan command can be used to display the name and unit number of
     each interface that is associated with a LAN card (see lanscan(1M)).

   Supernets
     A supernet is a collection of smaller networks.  Supernetting is a
     technique of using the netmask to aggregate a collection of smaller
     networks into a supernet. This technique is particularly useful for
     class C networks.  A Class C network can only have 254 hosts.  This
     can be too restrictive for some companies.  For these companies, a
     netmask that only contains a portion of the network part can be
     applied to the hosts in these class C networks to form a supernet.
     This supernet netmask should be applied to those interfaces that
     connect to the supernet using the ifconfig command.  For example, a
     host can configure its interface to connect to a class C supernet,
     192.6, by configuring an IP address of 192.6.1.1 and a netmask of
     255.255.0.0 to its interface.

DIAGNOSTICS
     Messages indicate if 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.

WARNINGS
     Currently, all HP 9000 systems can receive trailer packets but do not
     send them.  Setting the trailers flag has no effect.

SEE ALSO
     netstat(1), lanconfig(1m), lanscan(1m) hosts(4), routing(7).