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           ifconfig [interface]
           ifconfig interface [aftype] options | address ...


           This  program  is obsolete!  For replacement check ip addr and ip link.
           For statistics use ip -s link.


           Ifconfig is used to configure the kernel-resident  network  interfaces.
           It is used at boot time to set up interfaces as necessary.  After that,
           it is usually only needed when  debugging  or  when  system  tuning  is
           If  no  arguments  are  given, ifconfig displays the status of the cur-
           rently active interfaces.  If a single interface argument is given,  it
           displays  the  status of the given interface only; if a single -a argu-
           ment is given, it displays the status of  all  interfaces,  even  those
           that are down.  Otherwise, it configures an interface.

    Address Families

           If  the  first  argument  after the interface name is recognized as the
           name of a supported address family, that address  family  is  used  for
           decoding  and  displaying  all protocol addresses.  Currently supported
           address families include inet (TCP/IP,  default),  inet6  (IPv6),  ax25
           (AMPR  Packet  Radio),  ddp  (Appletalk  Phase 2), ipx (Novell IPX) and
           netrom (AMPR Packet radio).  All numbers supplied as parts in IPv4 dot-
           ted  decimal  notation may be decimal, octal, or hexadecimal, as speci-
           fied in the ISO C standard (that is, a leading 0x or  0X  implies  hex-
           adecimal; otherwise, a leading '0' implies octal; otherwise, the number
           is interpreted as decimal). Use of hexamedial and octal numbers is  not
           RFC-compliant and therefore its use is discouraged and may go away.


                  The  name  of the interface.  This is usually a driver name fol-
                  lowed by a unit number, for example eth0 for the first  Ethernet
           up     This  flag  causes the interface to be activated.  It is implic-
                  itly specified if an address is assigned to the interface.
           down   This flag causes the driver for this interface to be shut  down.
           [-]arp Enable or disable the use of the ARP protocol on this interface.
           dstaddr addr
                  Set  the  remote  IP  address for a point-to-point link (such as
                  PPP).  This keyword is now obsolete; use the pointopoint keyword
           netmask addr
                  Set the IP network mask for this interface.  This value defaults
                  to the usual class A, B or C network mask (as derived  from  the
                  interface IP address), but it can be set to any value.
           add addr/prefixlen
                  Add an IPv6 address to an interface.
           del addr/prefixlen
                  Remove an IPv6 address from an interface.
                  Create  a new SIT (IPv6-in-IPv4) device, tunnelling to the given
           irq addr
                  Set the interrupt line used by this device.  Not all devices can
                  dynamically change their IRQ setting.
           io_addr addr
                  Set the start address in I/O space for this device.
           mem_start addr
                  Set  the  start  address  for shared memory used by this device.
                  Only a few devices need this.
           media type
                  Set the physical port or medium type to be used by  the  device.
                  Not all devices can change this setting, and those that can vary
                  in what values  they  support.   Typical  values  for  type  are
                  10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps Ethernet),
                  AUI (external transceiver) and so on.  The special  medium  type
                  of  auto can be used to tell the driver to auto-sense the media.
                  Again, not all drivers can do this.
           [-]broadcast [addr]
                  If the address argument is given,  set  the  protocol  broadcast
                  address  for  this  interface.   Otherwise,  set  (or clear) the
                  IFF_BROADCAST flag for the interface.
           [-]pointopoint [addr]
                  This keyword enables the point-to-point mode  of  an  interface,
                  meaning  that  it  is  a  direct  link between two machines with
                  nobody else listening on it.
                  If the address argument is also given, set the protocol  address
                  of  the  other  side of the link, just like the obsolete dstaddr
                  The IP address to be assigned to this interface.
           txqueuelen length
                  Set the length of the transmit queue of the device. It is useful
                  to  set  this  to  small  values  for slower devices with a high
                  latency (modem links, ISDN) to prevent fast bulk transfers  from
                  disturbing interactive traffic like telnet too much.


           Since kernel release 2.2 there are no explicit interface statistics for
           alias interfaces anymore.  The  statistics  printed  for  the  original
           address  are shared with all alias addresses on the same device. If you
           want per-address statistics you should add  explicit  accounting  rules
           for the address using the ipchains(8) command.
           Interrupt  problems  with Ethernet device drivers fail with EAGAIN. See
  for more information.




           Ifconfig uses obsolete kernel interface.   It  uses  the  ioctl  access
           method  to  get  the  full  address  information, which limits hardware
           addresses to 8 bytes.  Since an Infiniband address is  20  bytes,  only
           the first 8 bytes of Infiniband address are displayed.
           While  appletalk DDP and IPX addresses will be displayed they cannot be
           altered by this command.




           Fred N. van Kempen, <>
           Alan Cox, <>
           Phil Blundell, <>
           Andi Kleen

    net-tools 14 August 2000 IFCONFIG(8)


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