hpux ifconfig man page on unix.com

ifconfig(1M) ifconfig(1M)

NAME
ifconfig - configure network interface parameters

SYNOPSIS
mod1[,mod2]...] interface [address_family] [address[dest_address]] [parameters]

interface [address_family]

DESCRIPTION
The first form of the command assigns an address to a network interface and/or configures network interface parameters. must be used at
boot time to define the network address of each interface present on a machine. It can also be used at other times to redefine an inter-
face's address or other operating parameters. If the address_family is not specified, the address family defaults to IPv4.

The second form of the command, without address_family, displays the current configuration for interface. If address_family is not speci-
fied, reports the details on all supported address families. An exception is when the user has not configured any interface with an IPv6
address, does not display the IPv6 loopback interface.

Only a user with appropriate privileges can modify the configuration of a network interface. All users can run the second form of the com-
mand.

Arguments
recognizes the following arguments:

A list of modules that can be pushed on a stream associated with an interface.
The option can be used to configure an interface manually with the specified module names. There is no space between the
module names and only a comma is used to separate the module names. If the option is specified, pushes all modules on the
stream associated with the interface in the specified order. For example, module mod2 is pushed on top of module mod1. The
modules are pushed between IP and network drivers. If the option is not specified, the modules (if any) specified in the
DEFAULT_INTERFACE_MODULES variable are used for configuring the interface (see and in

address Either a host name present in the host name database (see hosts(4)), or a DARPA Internet address expressed in Internet stan-
dard dot notation (see inet(3N)) for an IPv4 address and in colon notation (see inet6(3N)) for an IPv6 address.

address_family Name of protocol on which naming scheme is based. An interface can receive transmissions in differing protocols, each of
which may require separate naming schemes. The address_family, affects the interpretation of the remaining parameters on
the command line. The only address families currently supported are (DARPA-Internet family) for IPv4 addresses, and for
IPv6 addresses.

dest_address Address of destination system. Consists of either a host name present in the host name database (see hosts(4)), or a DARPA
Internet address expressed in Internet standard dot notation (see inet(3N)) for an IPv4 address, and in colon notation (see
inet6(3N)) for an IPv6 address.

interface A string of the form nameunit, such as (See the subsection given below.)

parameters One or more of the following operating parameters:

Mark an interface "up".
Enables interface after an Occurs automatically when setting the address on an interface. Setting this flag
has no effect if the hardware is "down". A secondary interface (see the Interface Naming subsection given
below) can be marked up only if the primary interface is already up.

Mark an interface "down".
When an interface is marked "down", the system will not attempt to transmit messages through that interface.
A primary interface (see the Interface Naming subsection given below) can be marked down only if all the sec-
ondary interfaces on the same physical device are already down.

(inet only) Specify the address that represents broadcasts to the network. The default broadcast address is the address
with a host part of all 1's.

Specify the tunnel encapsulation limit value
n. The tunnel encapsulation limit is the maximum number of additional encapsulations permitted for the pack-
ets. The tunnel encapsulation limit option is defined in RFC 2473. This option is valid only for tunnel
types and The default is 4.

(inet6 only) Enable forwarding of packets by this interface.
This is the default behavior.

(inet6 only) Disable forwarding of packets by this interface.

Set the routing metric of the interface to
n. The default is 0. The routing metric is used by the routing protocol (see gated(1M)). Higher metrics
have the effect of making a route less favorable; metrics are counted as additional hops to the destination
network or host.

(inet only) Specify how much of the address to reserve for subdividing networks into sub-networks or aggregating networks
into supernets. mask can be specified as a single hexadecimal number with a leading with a dot-notation
Internet address, or with a pseudo-network name listed in the network table (see networks(4)).

For subdividing networks into sub-networks, mask must include the network part of the local address, and the
subnet part which is taken from the host field of the address. mask must contain 1's in the bit positions in
the 32-bit address that are to be used for the network and subnet parts, and 0's in the host part. The 1's
in the mask must be contiguous starting from the leftmost bit position in the 32-bit field. mask must con-
tain at least the standard network portion, and the subnet field must be contiguous with the network portion.
The subnet field must contain at least 1 bit.

For aggregating networks into supernets, mask must only include a portion of the network part. mask must
contain contiguous 1's in the bit positions starting from the leftmost bit of the 32-bit field.

(inet6 only) n indicates the length of the network prefix associated with this interface. The primary interface (see
Interface Naming subsection given below) prefix length is always 10, and is not configurable. The prefix
option can be used only with the address option, and only for secondary interfaces. Default: 64. Range: 1
to 128.

(inet6 only) Enable processing of received router advertisements.
Secondary address(es) will be autoconfigured on the interface using the prefix(es) received in router adver-
tisement(s). This is the default behavior.

(inet6 only) Disable processing of received router advertisements.

(inet6 only) Specify that the address configured is an anycast
address. Anycast addresses can be specifed for secondary interfaces only. Once the anycast address is con-
figured, the secondary interface needs to be marked down before configuring a new IPv6 unicast or anycast
address on that secondary interface.

Specify the type of tunnel. The tunnel types can be and

Specify the destination
addr of the tunnel. This is the destination address in the encapsulating (outer) header. It should be an
unicast address configured on an interface on the tunnel exit-point node. For tunnel types and the addr
should be an IPv6 address. For tunnel type the addr should be an IPv4 address; and for tunnel type the tdst
parameter should not be specified.

Specify the source
addr of the tunnel. This is the source address in the encapsulating (outer) header. It should be an unicast
address configured on an interface in the tunnel entry-point node. For tunnel types and the addr should be
an IPv6 address. For tunnel types and the addr should be an IPv4 address.

(inet only) Enable the user of the Address Resolution Protocol in mapping between network level addresses and link level
addresses (default). If an interface already had the Address Resolution Protocol disabled, the user must
"unplumb" the interface before it can be enabled for Address Resolution Protocol.

(inet only) Disable the use of the Address Resolution Protocol. If an interface already had the Address Resolution Pro-
tocol enabled, the user must "unplumb" the interface before it can be disabled for Address Resolution Proto-
col.

Setup the Streams plumbing needed for TCP/IP for a primary interface name.
(See the subsection given below.). By default, the operation is done automatically when an IP address is
specified for an interface.

Tear down the Streams plumbing for a primary interface name.
(See the subsection given below.) Secondary interface does not require "plumbing". A secondary IPv4 inter-
face can be removed by assigning an IP address of 0.0.0.0 to it. Remove a secondary IPv6 interface by
assigning an IP address of :: to it.

Interface Naming
The interface name associated with a network card is composed of the name of the interface (e.g. or ), the ppa number which identifies the
card instance for this interface, and an optional IP index number which allows the configuration of multiple IP addresses for an interface.
For LAN cards, the interface name will be used to designate Ethernet encapsulation and for IEEE 802.3 encapsulation. The and commands can
be used to display the interface name and ppa number of each interface that is associated with a network card (see nwmgr(1M) and lan-
scan(1M)).

IPv4 and IPv6 interfaces can coexist over the same physical network interface device using the same naming scheme. IPv6 interfaces are
configured using the "inet6" ifconfig subcommand. (See the IPv6 subsection given below.)

The tunnel interface names should be for "IP6-in-IP" tunnels and tunnels. Example: The tunnel interface names should be for "IP-in-IP6"
tunnels and "IP6-in-IP6" tunnels. Example:

IP Index Number
Multiple IP addresses assigned to the same interface may be in different subnets. An example of an interface name without an IP index num-
ber is An example of an interface name with a IP index number is Note: specifying is equivalent to

A primary interface is an interface whose IP index number is zero. A secondary interface is an interface whose IP index number is non-
zero.

Loopback Interface
The loopback interface is automatically configured when the system boots with the TCP/IP software. The IP address and netmask of the pri-
mary IPv4 loopback interface are 127.0.0.1 and 255.0.0.0, respectively. The IP address and prefix of the primary IPv6 loopback interface
are ::1 and 128 respectively. The user is not permitted to change the address of the primary loopback interface It is permissible to
assign other IP addresses to lo0 with non-zero IP index numbers (lo0:1, lo0:2, etc). This allows a system to have a "system IP" address
that is available as long as one interface remains usable.

Supernets
(inet only) A supernet is a collection of smaller networks. Supernetting is a technique of using the netmask to aggregate a collection of
smaller networks into a supernet.

This technique is particularly useful when the limit of 254 hosts per class C network is too restrictive. In those situations a netmask
containing only a portion of the network part may be applied to the hosts in these networks to form a supernet. This supernet netmask
should be applied to those interfaces that connect to the supernet using the command. For example, a host can configure its interface to
connect to a class C supernet, 192.6, by configuring an IP address of 192.6.1.1 and a netmask of 255.255.0.0 to its interface.

IPv6 Interfaces
inet6 must be specified when an IPv6 interface is configured. The address for an IPv6 interface can either be a hostname present in the
host name database (see hosts(4)), or an address in the IPv6 colon notation.

Unlike IPv4 interfaces, IPv6 interfaces can be configured without an address and/or a prefix. Stateless address autoconfiguration requires
no manual configuration of hosts, minimal (if any) configuration of routers, and no additional servers.

A primary interface is automatically assigned a link-local address by the system when the interface is configured. A link-local address
comprises the well-known link-local prefix FE80::/10 and the interface identifier, which is typically 64 bits long and is based on EUI-64
identifiers. The link-local address allows automatic discovery of other hosts and routers on the same link, using the Neighbor Discovery
Protocol (see NDP(7P)). The link-local address can be used as the source address to communicate with other nodes when no routers are
present.

If a router on the local link advertises prefixes in router advertisements, the host autoconfigures its secondary interfaces and its
default gateway. The address of an autoconfigured secondary interface is formed by prepending the prefix received from the router to the
interface identifier, the same interface identifier that is used in forming the primary interface.

IPv6 interfaces can also be configured with manually assigned addresses and/or prefixes. A primary interface must be configured with a
link-local address and the prefix must not be specified. The prefix is always 10. The universal/local bit, the U bit, of the interface
identifier must be 0, per section 2.5.1 of RFC 2373. Accordingly, a manually assigned address for a primary interface must have the fol-
lowing pattern: where x is any hexadecimal digit, and M must be 0, 1, 4, 5, 8, 9, C, or D.

When a primary interface is configured with a manually assigned address, secondary interfaces will be autoconfigured if the host receives
prefixes from router advertisements. The addresses on the secondary interfaces will be derived from the interface identifier portion of
manually configured address in the primary interface.

When a secondary interface is configured with a manually assigned address, and if the user chooses an IP index number that has been used
for an autoconfigured secondary interface, the manual configuration overwrites the autoconfiguration. When this happens, network connec-
tivity through the overwritten autoconfigured IP address is temporarily lost. At a later time, when the host receives the next router
advertisement, the host will bring up another secondary interface with a different IP index number, but with the same IP address, and net-
work connectivity through that IP address is restored. Normally, a user can avoid this by checking used IP index numbers. However, there
is always a possibility that address autoconfiguration due to router advertisement is happening concurrently while the user manually con-
figures secondary interfaces.

To disable communication through a specific IP address on an autoconfigured secondary interface, that secondary interface should be marked
down, not removed or overwritten with a different IP address. If that interface is removed or overwritten, the host will reconfigure
another secondary interface with the same IP address when it receives the next router advertisement. Alternatively, the router can be con-
figured to stop advertising the prefix that corresponds to the offending IP address.

Anycast addresses can only be manually configured and their configuration will overwrite any manual or auto-configured address on the sec-
ondary interface.

An IPv6 interface may have four new flags that are not present on an IPv4 interface: and The flag is set for the tunnel interfaces. The
flag is set for autoconfigured secondary interfaces. The flag is set for interfaces with IP addresses that can be reached without going
through a router. The flag is set for secondary interfaces configured with an anycast address.

Stateless address autoconfiguration with link-local address

Manual configuration for a primary interface with link-local address

Manual configuration for a secondary interface with link-local address

Manual configuration for a secondary interface with global address

Manual configuration for a secondary interface with an anycast address

Tunnel interface configuration:
HP-UX supports "IP6-in-IP" configured tunnels as specified in RFC 4213, "IP-in-IP6" and "IP6-in-IP6" configured tunnels as specified in RFC
2473, and automatic tunnel as specified in RFC 3056.

"IP6-in-IP" configured tunnel allows dual stack IPv6/IPv4 nodes to communicate over an IPv4 infrastructure, by encapsulating the IPv6
packet inside an IPv4 header. The tunnel configuration must be done on both the local (tunnel entry-point) system and the remote (tunnel
exit-point) system. "IP6-in-IP" tunnels can be configured as shown below:

The source and destination link-local IPv6 addresses of the tunnel interface are optional; if they are not specified, they will be autocon-
figured based on the tunnel_local_IPv4_address and tunnel_remote_IPv4_address, respectively.

The tunnel_local_IPv4_address should be an address configured on the local system, and tunnel_remote_IPv4_address should be an address con-
figured on the remote system.

Example. On the local system:

Example. On the remote system:

If multiple tunnels are configured with the same tunnel_local_IPv4_address, autoconfiguration of only the first tunnel will succeed. Other
tunnels should be manually configured with link-local addresses.

Manual link-local addresses can be assigned to the tunnel interface as shown below:

Secondary addresses to the tunnel interfaces can be assigned as shown below:

"IP-in-IP6" tunnel configuration allows transmission of IPv4 packets encapsulated in an IPv6 header. "IP-in-IP6" tunnels can be configured
as shown below:

The tunnel_local_IPv6_address should be an unicast address configured on the local system, and tunnel_remote_IPv6_address should be an uni-
cast address configured on the remote system. The tunnel configuration should be done on both the local and the remote systems.

Example. On the local system:

Example. On the remote system:

"IP6-in-IP6" tunnel configuration allows transmission of IPv6 packets encapsulated in an IPv6 header. "IP6-in-IP6" tunnels can be config-
ured as shown below:

Example. On the local system:

Example. On the remote system:

tunnel configuration allows automatic tunneling of IPv6 packets encapsulated in an IPv4 header over an IPv4 infrastructure. tunnel inter-
face can be configured as shown below:

The tunnel_local_IPv4_address should be a global IPv4 address. The primary address of the interface should be a address and not a link-
local address. The primary address is optional, if it is not specified, a address will be autoconfigured based on tun-
nel_local_IPv4_address.

Example:

A address can be manually assigned as shown below:

To advertise a prefix, see rtradvd(1M).

DIAGNOSTICS
Messages indicate if the specified interface does not exist, the requested address is unknown, or the user is not privileged and tried to
alter an interface's configuration.

WARNINGS
The and commands are deprecated. These commands will be removed in a future HP-UX release. HP recommends the use of replacement command
nwmgr(1M) to perform all network interface-related tasks.

AUTHOR
was developed by HP and the University of California, Berkeley.

SEE ALSO
netstat(1), lanscan(1M), nwmgr(1M), route(1M), rtradvd(1M), inet(3N), inet6(3N), hosts(4), NDP(7P), route(7P), routing(7).

IP Version 6 Addressing Architecture, RFC4291, Hinden, Deering.

Basic Transition Mechanisms for IPv6 Hosts and Routers, RFC 4213, Nordmark, Gilligan.

Generic Packet Tunneling in IPv6 Specification, RFC 2473, Conta, Deering.

Connection of IPv6 Domains via IPv4 Clouds, RFC 3056, Carpenter, Moore.

ifconfig(1M)

hpux man page for ifconfig