ifconfig

ifconfig - Display or configure network interface parameters.

 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).