Configure network interface parameters
ifconfig interface address_family [address [dest_address]] [parameters]
ifconfig [-m] [-L] interface [protocol_family]
ifconfig -a [-m] [-L] [-b] [-d] [-u] [-s] [protocol_family]
ifconfig -l [-b] [-d] [-u] [-s]
ifconfig -s interface
ifconfig -C
- -a
- Display information about all of the interfaces in the system.
- -b
- List only the broadcast interfaces.
- -C
- List all of the interface cloners available on the system, with no additional information.
This option is mutually exclusive with all other options and commands.
- -d
- List only the interfaces which are down.
- -L
- Display the address lifetime for IPv6 addresses, as a time offset string.
- -l
- List all available interfaces on the system, with no additional information.
This option is mutually exclusive with all other options and commands, except for
-b, -d, -s, -u.
- -m
- Display all of the supported media for all of the interfaces in the
system (used in conjunction with -a).
- -m interface
- Display all of the supported media for the specified interface.
- -s
- List only the interfaces that are connected.
- -s interface
- Query this interface for its media status.
If the interface supports reporting media status,
and it reports that it doesn't appear to be connected to a network,
ifconfig exits with status of 1 (false);
otherwise, it exits with zero (true).
Not all interface drivers support media status reporting.
- -u
- List only the interfaces which are up.
- interface
- The name of the interface to configure.
This is a string of the form name unit (e.g. en1)
- address
- Either a hostname present in the
/etc/hosts database,
hosts(5),
or a DARPA-Internet address expressed in the standard Internet "dot notation."
- address_family
- The address family that affects the interpretation of the remaining parameters.
Specifying an address family is recommended since an interface can receive
transmissions in differing protocols with different naming schemes.
Address or protocol families currently supported are "inet"
and "inet6".
- dest_address
- Address of the correspondent on the other end of a
point-to-point link (for pppx interfaces only).
- parameters
- See the
"Parameters"
section below.
- protocol_family
- Report only the details specific to this protocol family.
The ifconfig utility is used to assign an address and/or
configure parameters for a network interface. This utility must be run at
boot time to define the
network address of each interface present on a machine; it
may also be run later on to redefine an interface's address
or to configure other interface parameters.
When no optional parameters are specified, The ifconfig utility displays the current configuration for a
network interface. If a protocol family is specified,
it will report only the details specific to that protocol family.
Note that only a superuser may modify the configuration of a network
interface.
You may set the following parameters with the ifconfig utility:
- alias
- Establish an additional network address for this interface. This is
useful when someone changes network
address of an interface, or when someone wishes to accept packets addressed to
the old interface.
- -alias
- Remove the additional network address for this interface.
- arp
- Enable the use of the Address Resolution Protocol in
mapping between network-level addresses and link-level addresses
(default). This is implemented to do mapping between DARPA Internet addresses
and 10 Mbits/sec Ethernet addresses.
- -arp
- Disable the use of the Address Resolution Protocol.
- anycast
- ("inet6" only) Set the IPv6 anycast address bit.
- -anycast
- ("inet6" only) Clear the IPv6 anycast address bit.
- broadcast mask
- ("inet" only) Use this address to represent broadcasts to the network.
The default broadcast address is the address with a host part of all 1's.
- create
- Create the specified network pseudo-device.
- delete
- Remove a specified network address. You should use this parameter
if you have incorrectly specified an alias,
or you will no longer use an alias. In the event that you have incorrectly set an NS
address which has the side effect of specifying the host portion, you must
respecify the host portion while removing all NS addresses. Note that
this parameter does not work for IPv6 addresses.
If you need to delete IPv6 addresses, use -alias with an explicit IPv6 address.
- deletetunnel
- Unconfigure the physical source and destination address for the IP tunnel interfaces
previously configured with tunnel.
- destroy
- Destroy the specified network pseudo-device.
- dest_address
- Specify the address of the correspondent on the other end of a
point-to-point link.
- down
- Mark an interface "down." When an interface
is marked down, the system won't attempt to transmit
messages through that interface. If possible, the interface
is reset to disable reception as well. This action
doesn't automatically disable routes using the interface.
- ip4csum[-rx][-tx]
- Enable hardware checksumming of ip4 headers on the
interface provided it's supported. This action can be
restricted to either rx or tx directions depending on
hardware limitations or user preference.
- -ip4csum[-rx][-tx]
- Disable hardware checksumming of ip4 headers on the interface.
- link[0-2]
- Enable special processing at the link-level for the interface.
Whereas three options are interface-specific in actual effect,
they're generally used to select special modes of operation.
An example of this is to enable SLIP compression,
or to select the connector type for some Ethernet cards.
For more information, refer to the documentation for the specific driver.
- -link[0-2]
- Disable special processing at the link-level for the specified interface.
- metric n
- Set the routing metric of the interface to n
(default is 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
additional hops to the destination network or host.
- mtu n
- Set the maximum transmission unit of the interface to n.
Most interfaces don't support this parameter.
- netmask mask
- ("inet", "inet6" and ISO) Reserve this much of the address 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
- can be specified as a single hex number with a leading
0x, with a dot-notation Internet address, or with
a pseudo-network name listed in the network table,
networks(5)
- contains 1's for the bit positions in the 32-bit address
that are to be used for the network and the subnet parts, and
0's for the host part
- should contain at least the standard network portion;
the subnet field should be contiguous with the network
portion.
For "inet" and "inet6" addresses,
the netmask can also be given with slash-notation after the address
(e.g. 192.168.17.3/24).
- pltime n
- ("inet6" only)
Use this value as the preferred lifetime for the address.
- prefixlen n
- ("inet6" only)
Set the prefix length (the effect is similar to netmask).
- tcp4csum[-rx][-tx]
- Enable hardware checksumming of tcp4 packets on the interface provided
it's supported. This action can be restricted to
either rx or tx directions depending on hardware
limitations or user preference.
- -tcp4csum[-rx][-tx]
- Disable hardware checksumming of tcp4 packets on the interface.
- tentative
- ("inet6" only)
Set the IPv6 tentative address bit.
- -tentative
- ("inet6" only)
Clear the IPv6 tentative address bit.
- tunnel src_addr dest_addr
- (IP tunnel devices only)
Configure the physical source and destination address for IP tunnel interfaces (GIF).
The src_addr and dest_addr arguments are interpreted as the outer source or destination
for the encapsulating IPv4/IPv6 header.
- udp4csum[-rx][-tx]
- Enable hardware checksumming of udp4 packets on the
interface provided it's supported. This action can be
restricted to either rx or tx directions depending on hardware
limitations or user preference.
- -udp4csum[-rx][-tx]
- Disable hardware checksumming of udp4 packets on the
interface.
- up
- Mark an interface "up." You can use this
command to enable an interface once it has been turned
"down" using
ifconfig down. By default, an interface is
marked as "up" the first time the ifconfig
utility is run to assign the interface an address. If the interface
is reset when previously marked as "down", the hardware will be
initialized.
- vlan tag
- Set the VLAN tag to tag if the interface is a vlan(4)
pseudo-interface. This 16-bit number is used to create a 802.1Q
VLAN header for the packets sent from the vlan(4) interface. Note
that vlan and vlanif must be set at the same time.
- vlanif iface
- Associate the physical interface iface if the
interface is a vlan(4) pseudo-interface.
Packets transmitted through the vlan(4) interface will
be diverted to the specified physical interface iface with
802.1Q VLAN encapsulation. Packets with 802.1Q encapsulation received
by the physical interface with the correct VLAN tag will
be diverted to the associated vlan(4) pseudo-interface.
The VLAN interface is assigned a copy of the physical
interface's flags and Ethernet address. This command will fail if the
vlan(4) interface already has a physical interface associated with
it. In order to change this association to
another physical interface, the existing association must
be cleared first. Note that vlanif and
vlan must be set at the same time.
- vltime n
- ("inet6" only) Set valid lifetime for the address.
Depending on the error, the utility may display messages indicating:
- the specified interface doesn't exist
- the requested address is unknown
- the user isn't privileged and tried to alter an
interface's configuration.
/etc/autoconnect,
netmanager,
netstat,
phlip,
routed
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