IFCONFIG(8C) BSD IFCONFIG(8C)
NAME
ifconfig - configure network interface parameters
SYNOPSIS
/etc/ifconfig interface [ address_family ] [ address [ dest_address ] ] [
parameters ]
/etc/ifconfig interface [ protocol_family ]
DESCRIPTION
ifconfig is used to assign an address to a network interface and/or
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. The interface parameter is a
string of the form name unit, for example, eth0. Apollo nodes can
support four different types of physical network interfaces:
Apollo Token Ring dr0,1
IEEE 802.3 (Ethernet) eth0,1
IEEE 802.5 (IBM Token Ring) itr0,1
Serial Line (SLIP) sl0
When defining a serial line network interface, specify the network
address of the local interface first; then specify the address of the
destination end point of the link. Only one serial line per host is
supported. On nodes with more than one serial line, use line 1.
Since an interface may receive transmissions in differing protocols, each
of which may require separate naming schemes, it is necessary to specify
the address_family, which may change the interpretation of the remaining
parameters. The only address family currently supported by Apollo is
inet.
For the DARPA-Internet family, 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".
PARAMETERS
The following parameters may be set with ifconfig:
up Mark an interface "up". This may 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 will be re-initialized.
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.
trailers Request the use of a "trailer" link level encapsulation
when sending (default). If a network interface supports
trailers, the system will, when possible, encapsulate
outgoing messages in a manner which minimizes the number
of memory to memory copy operations performed by the
receiver. On networks that support the Address Resolution
Protocol (see arp(4P); currently, only 10 MB ETHERNET),
this flag indicates that the system should request that
other systems use trailers when sending to this host.
Similarly, trailer encapsulations will be sent to other
hosts that have made such requests. Currently used by
Internet protocols only.
-trailers Disable the use of a "trailer" link level encapsulation.
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 DARPA Internet addresses and 10MB ETHERNET
addresses.
-arp Disable the use of the Address Resolution Protocol.
metric n Set the routing metric of the interface to n, default 0.
The routing metric is used by the routing protocol
(routed(8c)). Higher metrics have the effect of making a
route less favorable; metrics are counted as addition hops
to the destination network or host.
debug Enable driver dependent debugging code; usually, this
turns on extra console error logging.
-debug Disable driver dependent debugging code.
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 can be specified as a single hexadecimal number with
a leading 0x, with a dot-notation Internet address, or
with a netmask name listed in the host table hosts(5).
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.
On Apollo hosts, if you use the netmask name "defaultmask"
with ifconfig, and "defaultmask" is listed in hosts(5)
with a subnet mask value, ifconfig succeeds and sets the
subnet mask to the value found in hosts. If "defaultmask"
is not found in the hosts file, ifconfig still succeeds
but sets the mask to the default for the address class.
For example, the default mask for a Class C network is
255.255.255.0
If you use a netmask name other than "defaultmask" and the
name is not in hosts(5) or networks(5), then ifconfig
fails. If you use 0 as the mask, then ifconfig will
assume the default mask for the address class.
netmask icmp-request
Specifies that the host should obtain its subnet mask from
local gateways, using the ICMP Address Mask Request/Reply
protcol. A node will respond to this request only if it is
a gateway (that is, it has more than one network interface
enabled) and if its own subnet mask was explicity set with
the "netmask mask" parameter (and it did not itself use
the ICMP request protocol). If the requesting host
receives no responses within 2 seconds, it assumes that
subnets are not in use on the network.
You also can enable this ICMP Address Mask protocol by
assigning the address 255.255.255.255 to the netmask name
"defaultmask" in the hosts file.
dest_addr Specify the address of the correspondent on the other end
of a point to point link.
broadcast (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.
If the host must interoperate with older TCP
implementations that require the 0-form IP broadcast
address, specify "broadcast 0."
ifconfig displays the current configuration for a network interface when
no optional parameters are supplied. 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.
DIAGNOSTICS
Messages indicating the specified interface does not exit, the requested
address is unknown, or the user is not privileged and tried to alter an
interface's configuration.
SEE ALSO
intro(4N), netstat(1), rc(8);
Configuring and Managing TCP/IP. "