10.3;ifconfig, revision 3.0, 90/10/15
ifconfig - configure network interface parameters
usage: /etc/ifconfig interface [address_family] [address [dest_address]] [parameters]
DESCRIPTION
The ifconfig command is used to assign an address to a network interface
and/or configure network interface parameters. The ifconfig command 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 the following physical network interfaces:
Apollo Token Ring dr0, dr1
IEEE 802.3 (Ethernet) eth0, eth1
IEEE 802.5 (IBM Token-Ring) itr0, itr1
Serial Line Internet sl0
Protocol (SLIP)
Fiber Distributed Data ftr0
Interface (FDDI)
When defining a serial line (SLIP) 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, 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; 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).
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 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. 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. 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 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 or networks, 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". You cannot specify this parameter when
configuring either a loopback or point-to-point interface.
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.
Domain/OS EXTENSIONS
The Domain/OS implementation of ifconfig includes the following
additional parameters:
macaddr [ addr | domain | default ]
(ETHERNET only) Change or display the physical layer (called
the Media Access Control (MAC)) address for the ETHERNET
controller. Use this parameter to change the controller's MAC
address if your communications software (for example,
Apollo/TECHnet) requires a different MAC address from the
controller's default address. Specify the new address in the
form xx:xx:xx:xx:xx:xx where "xx" is a hexadecimal string
representing one byte in the address. (For example: ifconfig
eth0 macaddr aa:0:4:0:33:4.) If you supply the keywords domain
or default rather than a hexadecimal value, ifconfig sets the
controller's MAC address to the default address. To display a
node's current MAC address, invoke the command speficying only
the interface. (For example: ifconfig eth0.)
Typically, you set the MAC address when booting the node by
placing the /etc/ifconfig macaddr command in an rc file.
However, you can change the MAC address while communications
products are running on the ETHERNET, by preceding this command
with the keyword force:. (For example: ifconfig eth0 macaddr
force:domain.)
The TCP/IP server does not need to be running if this is the
only option given to ifconfig. You must be logged in as root
to change a node's MAC address.
source_routing
Enable IEEE 802.5 source routing as specified in RFC 1042. By
default, source routing is enabled when you configure the 802.5
network interface with the ifconfig command. Specify this
parameter only when bringing up the 802.5 interface.
-source_routing
Disable IEEE 802.5 source routing as specified in RFC 1042.
Specify this parameter only when bringing up the 802.5
interface.
DIAGNOSTICS
Messages indicate that the specified interface does not exist, the
requested address is unknown, or the user is not privileged to alter an
interface's configuration.
SEE ALSO
netstat, rc;
Configuring and Managing TCP/IP.