IFCONFIG(8C)
NAME
ifconfig − configure network interface parameters
SYNTAX
/etc/ifconfig interface [ address [ dest_address ] ] [ parameters ]
DESCRIPTION
Ifconfig assigns an address to a network interface and/or configures network interface parameters. You must use Ifconfig at boot time to define the network address of each interface present on a machine. You can also use it at a later time to redefine an interface’s address. The interface parameter is a string of the form “name unit”, e.g. “en0”. The address is either a host name present in the host name data base, hosts(5), or a DARPA Internet address expressed in the Internet standard dot notation.
You can set the following parameters with ifconfig:
up Marks an interface “up.”
down Mark an interface “down.” When an interface is marked “down,” the system does not attempt to transmit messages through that interface.
trailers Enables the use of a trailer link level encapsulation when sending (default). If a network interface supports trailers, the system, when possible, encapsulates outgoing messages in a manner that minimizes the number of memory-to-memory copy operations performed by the receiver.
−trailers Disables the use of a trailer link level encapsulation.
arp Enables 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 DARPA Internet addresses and 10Mb/s Ethernet addresses.
−arp Disables the use of the Address Resolution Protocol.
debug Enables driver-dependent debugging code. Usually, this turns on extra console error logging.
−debug Disables driver dependent debugging code.
Ifconfig displays the current configuration for a network interface when no optional parameters are supplied.
Only the superuser can modify the configuration of a network interface.
DIAGNOSTICS
Messages indicating the specified interface do not exist, the requested address is unknown, the user tried to alter an interface’s configuration but is not privileged.