ifconfig(1M)ifconfig(1M)NAMEifconfig - configure network interface parameters
SYNOPSIS
/usr/etc/ifconfig [ -v ] interface address_family [ address [ dest_address ] ]
[ parameters ]
/usr/etc/ifconfig interface [ protocol_family ]
/usr/etc/ifconfig [ -v ] -a
DESCRIPTIONifconfig is used to assign an address to a network interface and/or
configure network interface parameters. ifconfig is invoked at boot time
from /etc/init.d/network to define the network address of each interface
present on a machine; you can also use it once the system is up to
redefine an interface's address or other operating parameters. The
interface parameter is a string of the form ``name unit'', for example,
enp0. Using the -a option shows status for all interfaces on the
machine.
If specified, the -v option causes additional information about specified
interfaces to be displayed, including speed.
Since an interface can receive transmissions in differing protocols, each
of which may require separate naming schemes, it is necessary to specify
the address_family, which can change the interpretation of the remaining
parameters. Currently, the ``inet'' and ``inet6'' address families are
supported.
For the Internet Version 4 family, the address is either an Internet
address expressed in the Internet standard ``dot notation'' (see
inet(3N)), or a hostname present in the hosts(4) file, /etc/hosts.
(Other hosts databases, such as named and NIS, are ignored.)
For the Internet Version 6 family, the address is either expressed in the
Internet standard ``colon notation'' (see inet6(3N)), or as a hostname.
Only the superuser can modify the configuration of a network interface.
The following parameters can be set with ifconfig:
up Mark an interface up. This can be used to enable an
interface after an ifconfig down. It happens
automatically when setting the first address on an
interface. If the interface was reset when previously
marked down, the hardware is reinitialized.
down Mark an interface down. When an interface is marked down,
the system does not attempt to transmit messages through
that interface. If possible, the interface is reset to
disable reception as well. This action does not
automatically disable routes using the interface. Packets
which have been queued for transmission may be dropped.
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arp Enable the use of the Address Resolution Protocol in
mapping between network level addresses and link level
addresses (default). It is used by a variety of data link
network interfaces such as Ethernet.
-arp Disable the use of the Address Resolution Protocol.
alias addr Establish an additional network address for this
interface. This can be useful in permitting a single
physical interface to accept packets addressed to several
different addresses such as when you are changing network
numbers and you wish to accept packets addressed to the
old interface. Another case is when you'd like to have
multiple addresses assigned to a single network interface.
The broadcast and netmask options can also be used in
conjunction with the alias option. When using aliases you
may have to change the configuration of routed, especially
if aliases are on different networks than the primary
address. Aliases are added as host entries in the routing
tables for routed. See routed(1M) for more information on
this.
-alias|delete addr
Deletes a previously added alias.
metric n Set the routing metric of the interface to n, default 0.
The routing metric is used by the routing protocol
(routed). Higher metrics have the effect of making a
route less favorable; metrics are counted as addition hops
to the destination network or host.
netmask mask Specify how much of the address to reserve for subdividing
networks into subnetworks. The mask includes the network
part of the local address and the subnet part, which is
taken from the host field of the address. 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 network table
networks(4). The mask contains 1's for the bit positions
in the 32-bit address that 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 network portion, and
the subnet field should be contiguous with the network
portion.
prefixlen len Specify the prefix length of the address. For use with
inet6 addresses only. The prefix length is expressed as a
non-negative integer, less than or equal to 128. It
represents the number of bits in the address which are to
be interpreted as a prefix. It is also possible to specify
the prefix length using the slash notation, for example,
3ffe:100::a00:69ff:fe02:a2e7/64.
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mtu n Specify device maximum transmission unit value. This may
not be supported on all devices and some devices may only
offer limited support. Often, this is used to lower
ethernet MTU's below 1500 bytes to interoperate with buggy
adapters and network hardware. Also, on some gigabit
interfaces it can be used to increase the MTU to 9000 to
implement jumbo frames.
broadcast addr 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.
dest_addr Specify the address of the correspondent on the other end
of a point-to-point link.
debug Enable driver-dependent debugging code; usually, this
turns on extra console error logging.
-debug Disable driver-dependent debugging code.
highbw Flag an interface as being a high-bandwidth interface.
This acts as a hint which allows upper layer protocols to
adjust their behaviour to optimise performance (e.g. TCP
will be less aggressive with ACKing).
-highbw Remove the high-bandwidth flag from an interface.
link{0,1,2} Enable driver-specific feature 0-2.
-link{0,1,2} Disable driver-specific feature 0-2.
primary This parameter makes the specified interface the primary
interface for networking. In cases where no interface or
interface address is specified by an application, the
'primary' interface will be preferred.
rspace value Specifies the default receive space used by TCP when
communicating over the interface. Use a value of 0 to
clear this parameter and use the system-wide default.
sspace value Specifies the default send space used by TCP when
communicating over the interface. Use a value of 0 to
clear this parameter and use the system-wide default.
route Turn on the flag which indicates the system is routing on
the specified interface. This is useful only for
interfaces which have inet6 addresses and will cause
neighbor advertisements from the interface to have the
"IsRouter" flag set (if the system is configured as a
router). (By default all interfaces will have this flag
set at boot time if the system is configured as a router
and all interfaces will have this flag cleared at boot
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time if configured as a host.)
-route Turn off the flag which indicates the system is routing on
the specified interface. This is useful only for
interfaces which have inet6 addresses and will cause
neighbor advertisements from the interface to have the
"IsRouter" flag cleared.
stripe laddr raddr
Add a physical link to a stripe interface where laddr is
the local link interface address and raddr is the remote
link interface address. This command only applies to
stripe interfaces. Refer to the NOTES section below for
details.
-stripe laddr Remove a physical link from a stripe interface where laddr
matches the local link address of the link to be removed.
This command only applies to stripe interfaces.
stripelist List all of the addresses for the physical links
configured on a stripe interface. The same link
information is output when using verbose ( -v ) output.
This command only applies to stripe interfaces.
ifconfig displays the current configuration for a network interface when
no optional parameters are supplied. If a protocol family is specified,
ifconfig reports only the details specific to that protocol family.
NOTES
Network interfaces on Silicon Graphics systems can only receive and not
send packets that use ``trailer'' link-level encapsulation. Therefore,
ifconfig does not accept the trailers parameter.
For 100baseTX interfaces, such as 'ef', LINK0 being set indicates that
the device is operating at full-duplex. It is not currently possible to
force full- or half-duplex by setting or clearing this flag.
Currently options such as 'metric' are not handled for IP aliases;
adjusting the metric will affect only the primary address. 'broadcast'
and 'netmask' are the only options currently known to work properly with
IP aliases.
From 6.5.23, Irix supports Network Striping interfaces which allow
multiple physical interfaces to be combined at the IP layer into a
logical, routable interface called a stripe. For more details see the
Irix 6.5.23 release of Irix Admin: Network and Mail.
DIAGNOSTICS
Messages indicating 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.
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ifconfig(1M)ifconfig(1M)FILES
/etc/hosts host-address database
/etc/config/ifconfig-?.options site-specific options (1 file per
interface)
/etc/config/ipaliases.options interface-specific ip alias addresses
SEE ALSOnetstat(1), network(1M).
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