ifconfig(1M) manual page
Table of Contents
ifconfig - configure network interface parameters
/sbin/ifconfig
interface [ address_family ] [ address [ dest_address ] ] [ up ] [ down
] [ auto-revarp ] [ netmask mask ] [ broadcast address ] [ metric n
] [ mtu n ] [ trailers | -trailers ] [ private | -private ] [ arp | -arp
] [ plumb ] [ unplumb ]
/usr/sbin/ifconfig interface [ address_family ]
[ address [ dest_address ] ] [ up ] [ down ] [ auto-revarp ] [ netmask
mask ] [ broadcast address ] [ metric n ] [ mtu n ] [ trailers | -trailers
] [ private | -private ] [ arp | -arp ] [ plumb ] [ unplumb ]
SUNWcsu
ifconfig is used to assign an address to a network interface
and/or to configure network interface parameters. ifconfig 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. Used without options, ifconfig displays
the current configuration for a network interface. 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.
The interface parameter is a string of the form name physical-unit, for
example le0 or ie1, or of the form name physical-unit : logical-unit, for
example le0:1. Three special interface names, -a, -ad and -au, are reserved
and refer to all or a subset of the interfaces in the system. If one of
these interface names is given, the commands following it are applied to
all of the interfaces that match:
- -a
- Apply the commands to all interfaces
in the system.
- -ad
- Apply the commands to all ‘‘down’’ interfaces in the system.
- -au
- Apply the commands to all ‘‘up’’ interfaces in the system.
Since an interface
may receive transmissions in differing protocols, each of which may require
separate naming schemes, the parameters and addresses are interpreted according
to the rules of some address family, specified by the address_family parameter.
The address families currently supported are ether and inet. If no address
family is specified, inet is assumed.
For the TCP/IP
family (inet), the
address is either a host name present in the host name data base (see hosts(4)
)
or in the Network Information Service (NIS
) map hosts, or a TCP/IP
address
expressed in the Internet standard ‘dot notation’. Typically, an Internet
address specified in dot notation will consist of your system’s network
number and the machine’s unique host number. A typical Internet address is
192.9.200.44, where 192.9.200 is the network number and 44 is the machine’s host
number.
For the ether address family, the address is an Ethernet address
represented as x:x:x:x:x:x where x is a hexadecimal number between 0 and
FF.
If the dest_address parameter is supplied in addition to the address
parameter, it specifies the address of the correspondent on the other end
of a point to point link.
- arp
- Enable the use of the Address Resolution Protocol in mapping
between network level addresses and link level addresses (default). This
is currently implemented for mapping between TCP/IP
addresses and 10Mb/s
Ethernet addresses.
- -arp
- Disable the use of the Address Resolution Protocol.
- auto-revarp
- Use the Reverse Address Resolution Protocol (RARP) to automatically
acquire an address for this interface.
- down
- Mark an interface ‘down’. When
an interface is marked ‘down’, the system will not attempt to transmit messages
through that interface. If possible, the interface will be reset to disable
reception as well. This action does not automatically disable routes using
the interface.
- plumb
- Open the device associated with the physical interface
name and setup the streams needed for TCP/IP
to use the device. Before
this is done the interface will not show up in the output of ifconfig -a.
- unplumb
- Destroy any streams associated with this device and close the device.
After this command is executed the device name should not show up in the
output of ifconfig -a.
- private
- Tells the in.routed routing daemon that the
interface should not be advertised.
- -private
- Specify unadvertised interfaces.
- trailers
- This flag used to cause a non-standard encapsulation of inet packets
on certain link levels. Drivers supplied with this release no longer use
this flag, but it is ignored for compatibility.
- -trailers
- Disable the use
of a ‘trailer’ link level encapsulation.
- up
- Mark an interface ‘up’. This happens automatically when setting the first
address on an interface. The up option enables an interface after an ifconfig
down, reinitializing the hardware.
- broadcast address
- (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. A + (plus sign) given
for the broadcast value causes the broadcast address to be reset to a default
appropriate for the (possibly new) address and netmask. Note: The arguments
of ifconfig are interpreted left to right, and therefore
- ifconfig -a netmask
+ broadcast +
- and
- ifconfig -a broadcast + netmask +
- may result in different
values being assigned for the interfaces’
- broadcast addresses.
- metric n
- Set the routing metric of the interface to n, default 0. The
routing metric is used by the routing protocol Higher metrics have the
effect of making a route less favorable; metrics are counted as addition
hops to the destination network or host.
- mtu n
- Set the maximum transmission unit of the interface to n. For many
types of networks the mtu has an upper limit, for example, 1500 for Ethernet.
- netmask mask
- (inet only.) Specify how much of the address to reserve for
subdividing networks into sub-networks. 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 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 network
portion, and the subnet field should be contiguous with the network portion.
The mask can be specified in one of four ways: a) with a single hexadecimal
number with a leading 0x. b) with a dot-notation address, c) with a ‘+’ (plus
sign) address, or d) with a pseudo host name/pseudo network name listed
in the network table networks(4)
. If a ‘+’ (plus sign) is given for the netmask
value, the mask is looked up in the netmasks database using the interface
network number as the key.
- If a pseudo host name/pseudo network name is
- supplied as the netmask value, netmask data may be located in the hosts
or networks table. ifconfig first looks up the name in the hosts table.
If an entry is found, the host IP address is used as the netmask. If the
entry isn’t found there, ifconfig looks up the name in the networks table.
(If the entry is found there, the IP network address is padded with a zero.)
The hosts and netmasks tables are not designed for storage of netmasks;
adding a netmask entry by using this option may confuse other programs,
so we advise against using it. The system administrator may configure the
source and lookup order in the tables via the name service switch. See
nsswitch.conf(4)
for more information.
Solaris TCP/IP
allows multiple logical interfaces to be associated with a physical network
interface. This allows a single machine to be assigned multiple IP addresses,
even though it may have only one network interface. Physical network interfaces
have names of the form driver-name physical-unit-number, while logical interfaces
have names of the form driver-name physical-unit-number logical-unit-number.
A physical interface is configured into the system using the plumb sub-command,
for example:
- ifconfig le0 plumb
Once a physical interface has been "plumbed",
additional local interfaces can be configured by simply naming them in
subsequent ifconfig commands. Logical interfaces do not need to be "plumbed".
Simply mentioning their name in an ifconfig command is sufficient. For
example, the command:
- ifconfig le0:1
will allocate a logical interface
associated with the physical interface le0. A logical interface can be configured
with parameters (address, netmask, etc.) different from the physical interface
that it is associated with. And logical interfaces that are associated
with the same physical interface can be given different parameters as well.
Each logical interface must be associated with a physical interface. So,
for example, the logical interface le0:1 can only be configured after the
physical interface le0 has been plumbed.
If your workstation is
not attached to an Ethernet, the le0 interface should be marked ‘down’ as
follows:
- example% ifconfig le0 down
To print out the addressing information
for each interface, use the following command:
- example% ifconfig -a
To reset
each interface’s broadcast address after the netmasks have been correctly
set, use the next command:
- example% ifconfig -a broadcast +
To change the
Ethernet address for interface le0, use the following command:
- example%
ifconfig le0 ether aa:1:2:3:4:5
- /etc/netmasks
- netmask data
in.routed(1M)
,
netstat(1M)
, ethers(3N)
, hosts(4)
, netmasks(4)
, networks(4)
, nsswitch.conf(4)
,
arp(7P)
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.
It is recommended that
the names broadcast, down, private, trailers, up, and the other possible
option names not be selected when choosing host names. Choosing anyone
of these names as host names will cause bizarre problems that can be extremely
difficult to diagnose.
Table of Contents
![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level