ifconfig
Hurricane Electric Internet Services
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>
Hurricane Electric Internet Services
Copyright (C) 1998
Hurricane Electric.
All Rights Reserved.