ifconfig

NAME

       ifconfig - configure a network interface

SYNOPSIS

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

DESCRIPTION

       Ifconfig  is  used to set up (and maintain thereafter) the
       kernel-resident network interfaces.  It is  used  at  boot
       time  to configure most of them to a running state.  After
       that, it is usually only needed  when  debugging  or  when
       system tuning is needed.

       If no arguments are given, ifconfig just displays the sta-
       tus of the currently defined  interfaces.  If  the  single
       interface argument is given, it displays the status of the
       given interface only.  Otherwise, it assumes  that  things
       have to be set up.

Address Families

       If  the  first argument after the interface name is recog-
       nized 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) ax25 (AMPR Packet Radio.)
       ddp (Appletalk Phase 2) and ipx (Novell IPX).

OPTIONS

       interface
              The name of the NET interface.  This usually  is  a
              name  like  eth0  ,  sl3  or something like that: a
              device driver name followed by a unit number.

       up     This flag causes the interface to be activated.  It
              is implicitly specified if the interface is given a
              new address (see below).

       down   This flag causes the driver for this  interface  to
              be shut down, and is useful when things start going
              wrong.

       [-]arp Enable or disable the use of the  ARP  protocol  on
              this  interface.  If  the minus (-)sign is present,
              the flag is turned OFF.

       [-]trailers
              Enable or disable the use of trailers  on  Ethernet
              frames.   This is not used in the current implemen-
              tation of NET.

       [-]allmulti
              Enable or  disable  the  promiscuous  mode  of  the
              interface.  This means that all incoming frames get
              sent to the network layer  of  the  system  kernel,
              allowing for networking monitoring.

       metric N
              This  parameter  sets  the interface metric.  It is
              not used at present, but we implement  it  for  the
              future.

       mtu N  This parameter sets the Maximum Transfer Unit (MTU)
              of an interface.  For Ethernet, this is a number in
              the  range  of  1000-2000  (default  is 1500).  For
              SLIP, use something between 200  and  4096.   Note,
              that  the current implementation does not handle IP
              fragmentation yet, so you'd  better  make  the  MTU
              large enough!

       dstaddr addr
              Set  the  "other  end"'s  IP  address  in case of a
              Point-To-Point link, like PPP.   This  keywords  is
              obsoleted by the new 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  deducted from the interface IP address),
              but it can be set to any value for the use of  sub-
              netting.

       irq addr
              Set  the  interrupt  line used by this device. Many
              devices don't support dynamic IRQ setting.

       [-]broadcast [addr]
              If the address argument is also given, set the pro-
              tocol broadcast address for this interface.  Other-
              wise, it only sets the IFF_BROADCAST  flag  of  the
              interface.   If the keyword was preceded by a minus
              (-) sign, then the flag is cleared instead.

       [-]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  (or,
              at least we hope that this is the case, grin :-)
              If the address argument is also given, set the pro-
              tocol address of the other side of the  link,  just
              like the obsolete dstaddr keyword does.  Otherwise,
              it only sets the IFF_POINTOPOINT flag of the inter-
              face.   If  the keyword was preceded by a minus (-)
              sign, then the flag is cleared instead.

       hw     Set the hardware address of this interface, if  the
              device driver supports this operation.  The keyword
              must be followed by the name of the hardware  class
              and  the printable ASCII equivalent of the hardware
              address.   Hardware  classes  currently   supported
              include  ether  (Ethernet),  ax25 (AMPR AX.25), and
              ARCnet

       multicast
              Set the  multicast  flag  on  the  interface.  This
              should  not  normally  be needed as the drivers set
              the flag correctly themselves.

       address
              The host name or IP address (a host  name  will  be
              resolved  into  an  IP  address) of that interface.
              This parameter is  required,  although  the  syntax
              doesn't currently require it.

FILES

       /proc/net/socket /proc/net/dev

BUGS

       While  appletalk  DDP  and IPX addresses will be displayed
       they cannot be altered by this command.

AUTHORS

       Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org> Alan Cox,
       <Alan.Cox@linux.org>