4.4BSD/usr/share/man/cat8/ifconfig.0
IFCONFIG(8) BSD System Manager's Manual IFCONFIG(8)
NNAAMMEE
iiffccoonnffiigg - configure network interface parameters
SSYYNNOOPPSSIISS
iiffccoonnffiigg _i_n_t_e_r_f_a_c_e _a_d_d_r_e_s_s___f_a_m_i_l_y [_a_d_d_r_e_s_s [_d_e_s_t___a_d_d_r_e_s_s]] [_p_a_r_a_m_e_t_e_r_s]
iiffccoonnffiigg _i_n_t_e_r_f_a_c_e [_p_r_o_t_o_c_o_l___f_a_m_i_l_y]
DDEESSCCRRIIPPTTIIOONN
IIffccoonnffiigg is used to assign an address to a network interface and/or con-
figure network interface parameters. IIffccoonnffiigg must be used at boot time
to define the network address of each interface present on a machine; it
may also be used at a later time to redefine an interface's address or
other operating parameters.
Available operands for iiffccoonnffiigg::
_A_d_d_r_e_s_s
For the DARPA-Internet family, the address is either a host name
present in the host name data base, hosts(5), or a DARPA Inter-
net address expressed in the Internet standard ``dot notation''.
For the Xerox Network Systems(tm) family, addresses are
_n_e_t_:_a_._b_._c_._d_._e_._f, where _n_e_t is the assigned network number (in
decimal), and each of the six bytes of the host number, _a through
_f, are specified in hexadecimal. The host number may be omitted
on 10Mb/s Ethernet interfaces, which use the hardware physical
address, and on interfaces other than the first. For the ISO
family, addresses are specified as a long hexadecimal string, as
in the Xerox family. However, two consecutive dots imply a zero
byte, and the dots are optional, if the user wishes to (careful-
ly) count out long strings of digits in network byte order.
_a_d_d_r_e_s_s___f_a_m_i_l_y
Specifies the _a_d_d_r_e_s_s _f_a_m_i_l_y which affects interpretation of the
remaining parameters. Since an interface can receive transmis-
sions in differing protocols with different naming schemes, spec-
ifying the address family is recommeded. The address or protocol
families currently supported are ``inet'', ``iso'', and ``ns''.
_I_n_t_e_r_f_a_c_e
The _i_n_t_e_r_f_a_c_e parameter is a string of the form ``name unit'',
for example, ``en0''
The following parameters may be set with iiffccoonnffiigg:
aalliiaass Establish an additional network address for this inter-
face. This is sometimes useful when changing network
numbers, and one wishes to accept packets addressed to
the old interface.
aarrpp Enable the use of the Address Resolution Protocol in map-
ping between network level addresses and link level ad-
dresses (default). This is currently implemented for
mapping between DARPA Internet addresses and 10Mb/s Eth-
ernet addresses.
--aarrpp Disable the use of the Address Resolution Protocol.
bbrrooaaddccaasstt (Inet only) Specify the address to use to represent
broadcasts to the network. The default broadcast address
is the address with a host part of all 1's.
ddeebbuugg Enable driver dependent debugging code; usually, this
turns on extra console error logging.
--ddeebbuugg Disable driver dependent debugging code.
ddeelleettee Remove the network address specified. This would be used
if you incorrectly specified an alias, or it was no
longer needed. If you have incorrectly set an NS address
having the side effect of specifying the host portion,
removing all NS addresses will allow you to respecify the
host portion.
ddeesstt__aaddddrreessss Specify the address of the correspondent on the other end
of a point to point link.
ddoowwnn Mark an interface ``down''. When an interface is marked
``down'', the system will not attempt to transmit mes-
sages through that interface. If possible, the interface
will be reset to disable reception as well. This action
does not automatically disable routes using the inter-
face.
iippddsstt This is used to specify an Internet host who is willing
to receive ip packets encapsulating NS packets bound for
a remote network. An apparent point to point link is
constructed, and the address specified will be taken as
the NS address and network of the destination. IP encap-
sulation of CLNP packets is done differently.
mmeettrriicc _n Set the routing metric of the interface to _n, default 0.
The routing metric is used by the routing protocol
(routed(8)). Higher metrics have the effect of making a
route less favorable; metrics are counted as addition
hops to the destination network or host.
nneettmmaasskk _m_a_s_k (Inet and Iso) Specify how much of the address to reserve
for subdividing networks into sub-networks. The mask in-
cludes the network part of the local address and the sub-
net part, which is taken from the host field of the ad-
dress. The 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 net-
work table networks(5). The mask contains 1's for the
bit positions in the 32-bit address which are to be used
for the network and subnet parts, and 0's for the host
part. The mask should contain at least the standard net-
work portion, and the subnet field should be contiguous
with the network portion.
nnsseelllleennggtthh _n (ISO only) This specifies a trailing number of bytes for
a received NSAP used for local identification, the re-
maining leading part of which is taken to be the NET
(Network Entity Title). The default value is 1, which is
conformant to US GOSIP. When an iso address is set in an
ifconfig command, it is really the NSAP which is being
specified. For example, in US GOSIP, 20 hex digits
should be specified in the ISO NSAP to be assigned to the
interface. There is some evidence that a number differ-
ent 1 may be useful for AFI 37 type addresses.
ttrraaiilleerrss Request the use of a ``trailer'' link level encapsulation
when sending (default). If a network interface supports
ttrraaiilleerrss, the system will, when possible, encapsulate
outgoing messages in a manner which minimizes the number
of memory to memory copy operations performed by the re-
ceiver. On networks that support the Address Resolution
Protocol (see arp(4); currently, only 10 Mb/s Ethernet),
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.
--ttrraaiilleerrss Disable the use of a ``trailer'' link level encapsula-
tion.
lliinnkk[[00--22]] Enable special processing of the link level of the inter-
face. These three options are interface specific in ac-
tual effect, however, they are in general used to select
special modes of operation. An example of this is to en-
able SLIP compression. Currently, only used by SLIP.
--lliinnkk[[00--22]] Disables special processing at the link level with the
specified interface.
uupp Mark an interface ``up''. This may be used to enable an
interface after an ``ifconfig down.'' It happens auto-
matically when setting the first address on an interface.
If the interface was reset when previously marked down,
the hardware will be re-initialized.
IIffccoonnffiigg displays the current configuration for a network interface when
no optional parameters are supplied. If a protocol family is specified,
Ifconfig will report only the details specific to that protocol family.
Only the super-user may modify the configuration of a network interface.
DDIIAAGGNNOOSSTTIICCSS
Messages indicating the specified interface does not exit, the requested
address is unknown, or the user is not privileged and tried to alter an
interface's configuration.
SSEEEE AALLSSOO
netstat(1), netintro(4), rc(8), routed(8),
HHIISSTTOORRYY
The iiffccoonnffiigg command appeared in 4.2BSD.
4.2 Berkeley Distribution June 5, 1993 3