ifconfig(8c)
NAME
ifconfig − configure network interface parameters
SYNTAX
/etc/ifconfig interface [ address [ dest_address ] ] [ parameters ]
DESCRIPTION
The Ifconfig command 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”, for example, “en0”. The address is either a host name present in the host name data base, hosts(,), or a DARPA Internet address expressed in the Internet standard dot notation.
You can set the following parameters with ifconfig:
upMarks an interface “up.”
downMark an interface “down.” When an interface is marked “down,” the system does not attempt to transmit messages through that interface.
trailersEnables 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.
−trailersDisables the use of a trailer link level encapsulation.
arpEnables 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.
−arpDisables the use of the Address Resolution Protocol.
debugEnables driver-dependent debugging code. Usually, this turns on extra console error logging.
−debugDisables driver dependent debugging code.
netmaskSpecify how much of the address you wish to reserve for subdiving Class A and B networks into sub-networks. (Inet only).
dstaddrSpecify the correspondent on the other end of a point to point link
broadcastSpecify the address you wish to use to represent broadcasts to the network.
The ifconfig command 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.