IP


Section: Linux (8)
Updated: 17 January 2002
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NAME

ip – show / manipulate routing, devices, policy routing and tunnels
 

SYNOPSIS


ip

[ OPTIONS ] OBJECT { COMMAND |

help }




OBJECT := {

link | addr | addrlabel | route | rule | neigh | tunnel | maddr | mroute | monitor }




OPTIONS := {

-V[ersion] |
-s[tatistics] |
-r[esolve] |
-f[amily] {
inet | inet6 | ipx | dnet | link } |

-o[neline] }



ip link set DEVICE

{ up | down | arp { on | off } |


promisc { on | off } |


allmulticast { on | off } |


dynamic { on | off } |


multicast { on | off } |


txqueuelen

PACKETS |


name

NEWNAME |


address

LLADDR |

broadcast

LLADDR |


mtu

MTU |


netns

PID |


alias

NAME |


vf

NUM [

mac

LLADDR ] [

vlan

VLANID [

qos

VLAN-QOS ] ] [

rate

TXRATE ]

}




ip link show

[ DEVICE ]



ip addr { add | del }

IFADDR dev STRING



ip addr { show | flush } [ dev

STRING ] [

scope

SCOPE-ID ] [

to

PREFIX ] [ FLAG-LIST ] [

label

PATTERN ]



IFADDR := PREFIX | ADDR

peer

PREFIX [

broadcast

ADDR ] [

anycast

ADDR ] [

label

STRING ] [

scope

SCOPE-ID ]



SCOPE-ID :=

[ host | link | global |

NUMBER ]



FLAG-LIST := [ FLAG-LIST ] FLAG



FLAG :=

[ permanent | dynamic | secondary | primary | tentative | deprecated ]



ip addrlabel { add | del } prefix

PREFIX [

dev

DEV ] [

label

NUMBER ]



ip addrlabel { list | flush }



ip route {

list | flush }

SELECTOR



ip route get

ADDRESS [

from ADDRESS iif STRING

] [ oif

STRING ] [

tos

TOS ]



ip route { add | del | change | append | replace | monitor }

ROUTE



SELECTOR :=

[ root

PREFIX ] [

match

PREFIX ] [

exact

PREFIX ] [

table

TABLE_ID ] [

proto

RTPROTO ] [

type

TYPE ] [

scope

SCOPE ]



ROUTE := NODE_SPEC [ INFO_SPEC ]



NODE_SPEC := [ TYPE ] PREFIX [

tos

TOS ] [

table

TABLE_ID ] [

proto

RTPROTO ] [

scope

SCOPE ] [

metric

METRIC ]



INFO_SPEC := NH OPTIONS FLAGS [

nexthop

NH ] …



NH := [

via

ADDRESS ] [

dev

STRING ] [

weight

NUMBER ] NHFLAGS



OPTIONS := FLAGS [

mtu

NUMBER ] [

advmss

NUMBER ] [

rtt

TIME ] [

rttvar

TIME ] [

window

NUMBER ] [

cwnd

NUMBER ] [

initcwnd

NUMBER ] [

ssthresh

REALM ] [

realms

REALM ] [

rto_min

TIME ] [

initrwnd

NUMBER ]



TYPE := [

unicast | local | broadcast | multicast | throw | unreachable | prohibit | blackhole | nat ]



TABLE_ID := [

local| main | default | all |

NUMBER ]



SCOPE := [

host | link | global |

NUMBER ]



FLAGS := [

equalize ]



NHFLAGS := [

onlink | pervasive ]



RTPROTO := [

kernel | boot | static |

NUMBER ]



ip rule

[ list | add | del | flush ]

SELECTOR ACTION



SELECTOR := [

from

PREFIX ] [

to

PREFIX ] [

tos

TOS ] [

fwmark

FWMARK[/MASK] ] [

dev

STRING ] [

pref

NUMBER ]



ACTION := [

table

TABLE_ID ] [

nat

ADDRESS ] [

prohibit | reject | unreachable ] [ realms

[SRCREALM/]DSTREALM ]



TABLE_ID := [

local | main | default |

NUMBER ]



ip neigh { add | del | change | replace } {

ADDR [

lladdr

LLADDR ] [

nud { permanent | noarp | stale | reachable } ] | proxy

ADDR } [

dev

DEV ]



ip neigh { show | flush } [ to

PREFIX ] [

dev

DEV ] [

nud

STATE ]



ip tunnel { add | change | del | show | prl }

[ NAME ]


[ mode

MODE ] [

remote

ADDR ] [

local

ADDR ]


[ [i|o]seq ] [ [i|o]key

KEY ] [

[i|o]csum ] ]


[ encaplimit

ELIM ]

[ ttl

TTL ]


[ tos

TOS ] [

flowlabel

FLOWLABEL ]


[ prl-default

ADDR ] [

prl-nodefault

ADDR ] [

prl-delete

ADDR ]


[ [no]pmtudisc ]

[ dev

PHYS_DEV ]

[ dscp inherit ]



MODE :=

{ ipip | gre | sit | isatap | ip6ip6 | ipip6 | any }



ADDR := { IP_ADDRESS |

any }



TOS := { NUMBER |

inherit }



ELIM := {

none |

0..255 }




TTL := { 1..255 |

inherit }



KEY := { DOTTED_QUAD | NUMBER }



TIME := NUMBER[s|ms]



ip maddr [ add | del ]

MULTIADDR dev STRING



ip maddr show [ dev

STRING ]



ip mroute show [

PREFIX ] [

from

PREFIX ] [

iif

DEVICE ]



ip monitor [ all |

LISTofOBJECTS ]



ip xfrm

XFRM_OBJECT { COMMAND }



XFRM_OBJECT := { state | policy | monitor }



ip xfrm state { add | update }

ID [

XFRM_OPT ]

[ mode

MODE ]


[ reqid

REQID ]

[ seq

SEQ ]

[ replay-window

SIZE ]


[ flag

FLAG-LIST ]

[ encap

ENCAP ]

[ sel

SELECTOR ]


[

LIMIT-LIST ]



ip xfrm state allocspi

ID

[ mode

MODE ]

[ reqid

REQID ]

[ seq

SEQ ]

[ min

SPI

max

SPI ]



ip xfrm state { delete | get }

ID



ip xfrm state { deleteall | list } [

ID ]

[ mode

MODE ]


[ reqid

REQID ]

[ flag

FLAG_LIST ]



ip xfrm state flush [ proto

XFRM_PROTO ]



ip xfrm state count



ID :=

[ src

ADDR ]

[ dst

ADDR ]

[ proto

XFRM_PROTO ]

[ spi

SPI ]



XFRM_PROTO :=

[ esp | ah | comp | route2 | hao ]



MODE :=

[ transport | tunnel | ro | beet ]

(default=transport)



FLAG-LIST :=

[ FLAG-LIST ] FLAG



FLAG :=

[ noecn | decap-dscp | wildrecv ]



ENCAP := ENCAP-TYPE SPORT DPORT OADDR



ENCAP-TYPE :=

espinudp

|

espinudp-nonike



ALGO-LIST := [

ALGO-LIST ] | [

ALGO ]



ALGO :=

ALGO_TYPE

ALGO_NAME

ALGO_KEY



ALGO_TYPE :=

[ enc | auth | comp ]



SELECTOR :=

src

ADDR[/PLEN]

dst

ADDR[/PLEN]

[ UPSPEC ]

[ dev

DEV ]



UPSPEC :=

proto

PROTO [[

sport

PORT ]

[ dport

PORT ] |


[ type

NUMBER ]

[ code

NUMBER ]]



LIMIT-LIST := [ LIMIT-LIST ] |

[ limit

LIMIT ]



LIMIT :=

[ [time-soft|time-hard|time-use-soft|time-use-hard]

SECONDS ] |

[ [byte-soft|byte-hard]

SIZE ] |


[ [packet-soft|packet-hard]

COUNT ]



ip xfrm policy { add | update } dir

DIR

SELECTOR [

index

INDEX ]


[ ptype

PTYPE ]

[ action

ACTION ]

[ priority

PRIORITY ]


[ LIMIT-LIST ] [

TMPL-LIST ]



ip xfrm policy { delete | get } dir

DIR [ SELECTOR |

index

INDEX

]


[ ptype

PTYPE ]



ip xfrm policy { deleteall | list }

[ dir

DIR ] [

SELECTOR ]


[ index

INDEX ]

[ action

ACTION ]

[ priority

PRIORITY ]



ip xfrm policy flush

[ ptype

PTYPE ]



ip xfrm count



PTYPE :=

[ main | sub ]

(default=main)



DIR :=

[ in | out | fwd ]



SELECTOR :=

src

ADDR[/PLEN]

dst

ADDR[/PLEN] [ UPSPEC

] [ dev

DEV ]



UPSPEC :=

proto

PROTO [

[ sport

PORT ]

[ dport

PORT ] |


[ type

NUMBER ]

[ code

NUMBER ] ]



ACTION :=

[ allow | block ]

(default=allow)



LIMIT-LIST :=

[

LIMIT-LIST ] |

[ limit

LIMIT ]



LIMIT :=

[ [time-soft|time-hard|time-use-soft|time-use-hard]

SECONDS ] |

[ [byte-soft|byte-hard]

SIZE ] |


[packet-soft|packet-hard]

NUMBER ]



TMPL-LIST :=

[

TMPL-LIST ] |

[ tmpl

TMPL ]



TMPL :=

ID [

mode

MODE ]

[ reqid

REQID ]

[ level

LEVEL ]



ID :=

[ src

ADDR ]

[ dst

ADDR ]

[ proto

XFRM_PROTO ]

[ spi

SPI ]



XFRM_PROTO :=

[ esp | ah | comp | route2 | hao ]



MODE :=

[ transport | tunnel | beet ]

(default=transport)



LEVEL :=

[ required | use ]

(default=required)



ip xfrm monitor [ all |

LISTofOBJECTS ]



ip token { COMMAND | help }



ip token { set }

TOKEN

dev

DEV



ip token { get }

dev

DEV



ip token { list }


 

OPTIONS



-V, -Version


print the version of the
ip

utility and exit.


-s, -stats, -statistics


output more information. If the option
appears twice or more, the amount of information increases.
As a rule, the information is statistics or some time values.


-f, -family


followed by protocol family identifier:
inet, inet6

or
link

,enforce the protocol family to use. If the option is not present,
the protocol family is guessed from other arguments. If the rest
of the command line does not give enough information to guess the
family,
ip

falls back to the default one, usually
inet

or
any.

link

is a special family identifier meaning that no networking protocol
is involved.


-4


shortcut for
-family inet.


-6


shortcut for
-family inet6.


-0


shortcut for
-family link.


-o, -oneline


output each record on a single line, replacing line feeds
with the

character. This is convenient when you want to count records
with
wc(1)


 or to
grep(1)

the output.


-r, -resolve


use the system’s name resolver to print DNS names instead of
host addresses.



 

IP – COMMAND SYNTAX


 

OBJECT



link


– network device.


address


– protocol (IP or IPv6) address on a device.


addrlabel


– label configuration for protocol address selection.


neighbour


– ARP or NDISC cache entry.


route


– routing table entry.


rule


– rule in routing policy database.


maddress


– multicast address.


mroute


– multicast routing cache entry.


tunnel


– tunnel over IP.


xfrm


– framework for IPsec protocol.



The names of all objects may be written in full or
abbreviated form, f.e.
address

is abbreviated as
addr

or just
a.


 

COMMAND


Specifies the action to perform on the object.
The set of possible actions depends on the object type.
As a rule, it is possible to
add, delete

and
show

(or
list

) objects, but some objects do not allow all of these operations
or have some additional commands. The
help

command is available for all objects. It prints
out a list of available commands and argument syntax conventions.


If no command is given, some default command is assumed.
Usually it is
list

or, if the objects of this class cannot be listed,
help.


 

ip link – network device configuration


link

is a network device and the corresponding commands
display and change the state of devices.


 

ip link set – change device attributes



dev NAME (default)


NAME

specifies network device to operate on. When configuring SR-IOV Virtual Fuction
(VF) devices, this keyword should specify the associated Physical Function (PF)
device.


up and down


change the state of the device to
UP

or
DOWN.


arp on or arp off


change the
NOARP

flag on the device.


multicast on or multicast off


change the
MULTICAST

flag on the device.


dynamic on or dynamic off


change the
DYNAMIC

flag on the device.


name NAME


change the name of the device. This operation is not
recommended if the device is running or has some addresses
already configured.


txqueuelen NUMBER


txqlen NUMBER


change the transmit queue length of the device.


mtu NUMBER


change the
MTU

of the device.


address LLADDRESS


change the station address of the interface.


broadcast LLADDRESS


brd LLADDRESS


peer LLADDRESS


change the link layer broadcast address or the peer address when
the interface is
POINTOPOINT.


netns PID


move the device to the network namespace associated with the process
PID.


alias NAME


give the device a symbolic name for easy reference.


vf NUM


specify a Virtual Function device to be configured. The associated PF device
must be specified using the
dev

parameter.

mac LLADDRESS

– change the station address for the specified VF. The
vf

parameter must be specified.



vlan VLANID

– change the assigned VLAN for the specified VF. When specified, all traffic
sent from the VF will be tagged with the specified VLAN ID. Incoming traffic
will be filtered for the specified VLAN ID, and will have all VLAN tags
stripped before being passed to the VF. Setting this parameter to 0 disables
VLAN tagging and filtering. The
vf

parameter must be specified.



qos VLAN-QOS

– assign VLAN QOS (priority) bits for the VLAN tag. When specified, all VLAN
tags transmitted by the VF will include the specified priority bits in the
VLAN tag. If not specified, the value is assumed to be 0. Both the
vf

and
vlan

parameters must be specified. Setting both
vlan

and
qos

as 0 disables VLAN tagging and filtering for the VF.



rate TXRATE

– change the allowed transmit bandwidth, in Mbps, for the specified VF.
Setting this parameter to 0 disables rate limiting. The
vf

parameter must be specified.



Warning:

If multiple parameter changes are requested,
ip

aborts immediately after any of the changes have failed.
This is the only case when
ip

can move the system to an unpredictable state. The solution
is to avoid changing several parameters with one
ip link set

call.


 

ip link show – display device attributes



dev NAME (default)


NAME

specifies the network device to show.
If this argument is omitted all devices are listed.


up


only display running interfaces.



 

ip address – protocol address management.


The
address

is a protocol (IP or IPv6) address attached
to a network device. Each device must have at least one address
to use the corresponding protocol. It is possible to have several
different addresses attached to one device. These addresses are not
discriminated, so that the term
alias

is not quite appropriate for them and we do not use it in this document.


The
ip addr

command displays addresses and their properties, adds new addresses
and deletes old ones.


 

ip address add – add new protocol address.



dev NAME


the name of the device to add the address to.


local ADDRESS (default)


the address of the interface. The format of the address depends
on the protocol. It is a dotted quad for IP and a sequence of
hexadecimal halfwords separated by colons for IPv6. The
ADDRESS

may be followed by a slash and a decimal number which encodes
the network prefix length.


peer ADDRESS


the address of the remote endpoint for pointopoint interfaces.
Again, the
ADDRESS

may be followed by a slash and a decimal number, encoding the network
prefix length. If a peer address is specified, the local address
cannot have a prefix length. The network prefix is associated
with the peer rather than with the local address.


broadcast ADDRESS


the broadcast address on the interface.


It is possible to use the special symbols
‘+’

and
‘-‘

instead of the broadcast address. In this case, the broadcast address
is derived by setting/resetting the host bits of the interface prefix.


label NAME


Each address may be tagged with a label string.
In order to preserve compatibility with Linux-2.0 net aliases,
this string must coincide with the name of the device or must be prefixed
with the device name followed by colon.


scope SCOPE_VALUE


the scope of the area where this address is valid.
The available scopes are listed in file
/etc/iproute2/rt_scopes.

Predefined scope values are:

global

– the address is globally valid.


site

– (IPv6 only) the address is site local, i.e. it is
valid inside this site.


link

– the address is link local, i.e. it is valid only on this device.


host

– the address is valid only inside this host.



 

ip address delete – delete protocol address

Arguments:

coincide with the arguments of
ip addr add.

The device name is a required argument. The rest are optional.
If no arguments are given, the first address is deleted.


 

ip address show – look at protocol addresses



dev NAME (default)


name of device.


scope SCOPE_VAL


only list addresses with this scope.


to PREFIX


only list addresses matching this prefix.


label PATTERN


only list addresses with labels matching the
PATTERN.

PATTERN

is a usual shell style pattern.


dynamic and permanent


(IPv6 only) only list addresses installed due to stateless
address configuration or only list permanent (not dynamic)
addresses.


tentative


(IPv6 only) only list addresses which did not pass duplicate
address detection.


deprecated


(IPv6 only) only list deprecated addresses.


primary and secondary


only list primary (or secondary) addresses.



 

ip address flush – flush protocol addresses

This command flushes the protocol addresses selected by some criteria.


This command has the same arguments as
show.

The difference is that it does not run when no arguments are given.


Warning:

This command (and other
flush

commands described below) is pretty dangerous. If you make a mistake,
it will not forgive it, but will cruelly purge all the addresses.


With the
-statistics

option, the command becomes verbose. It prints out the number of deleted
addresses and the number of rounds made to flush the address list. If
this option is given twice,
ip addr flush

also dumps all the deleted addresses in the format described in the
previous subsection.


 

ip addrlabel – protocol address label management.


IPv6 address label is used for address selection
described in RFC 3484. Precedence is managed by userspace,
and only label is stored in kernel.


 

ip addrlabel add – add an address label

the command adds an address label entry to the kernel.


prefix PREFIX


dev DEV


the outgoing interface.
label NUMBER


the label for the prefix.
0xffffffff is reserved.

 

ip addrlabel del – delete an address label

the command deletes an address label entry in the kernel.
Arguments:

coincide with the arguments of
ip addrlabel add

but label is not required.
 

ip addrlabel list – list address labels

the command show contents of address labels.
 

ip addrlabel flush – flush address labels

the command flushes the contents of address labels and it does not restore default settings.
 

ip neighbour – neighbour/arp tables management.


neighbour

objects establish bindings between protocol addresses and
link layer addresses for hosts sharing the same link.
Neighbour entries are organized into tables. The IPv4 neighbour table
is known by another name – the ARP table.


The corresponding commands display neighbour bindings
and their properties, add new neighbour entries and delete old ones.


 

ip neighbour add – add a new neighbour entry

 

ip neighbour change – change an existing entry

 

ip neighbour replace – add a new entry or change an existing one


These commands create new neighbour records or update existing ones.



to ADDRESS (default)


the protocol address of the neighbour. It is either an IPv4 or IPv6 address.


dev NAME


the interface to which this neighbour is attached.


lladdr LLADDRESS


the link layer address of the neighbour.
LLADDRESS

can also be
null.


nud NUD_STATE


the state of the neighbour entry.
nud

is an abbreviation for ‘Neigh bour Unreachability Detection’.
The state can take one of the following values:

permanent

– the neighbour entry is valid forever and can be only
be removed administratively.



noarp

– the neighbour entry is valid. No attempts to validate
this entry will be made but it can be removed when its lifetime expires.



reachable

– the neighbour entry is valid until the reachability
timeout expires.



stale

– the neighbour entry is valid but suspicious.
This option to
ip neigh

does not change the neighbour state if it was valid and the address
is not changed by this command.



 

ip neighbour delete – delete a neighbour entry

This command invalidates a neighbour entry.


The arguments are the same as with
ip neigh add,

except that
lladdr

and
nud

are ignored.


Warning:

Attempts to delete or manually change a
noarp

entry created by the kernel may result in unpredictable behaviour.
Particularly, the kernel may try to resolve this address even
on a
NOARP

interface or if the address is multicast or broadcast.


 

ip neighbour show – list neighbour entries


This commands displays neighbour tables.



to ADDRESS (default)


the prefix selecting the neighbours to list.


dev NAME


only list the neighbours attached to this device.


unused


only list neighbours which are not currently in use.


nud NUD_STATE


only list neighbour entries in this state.
NUD_STATE

takes values listed below or the special value
all

which means all states. This option may occur more than once.
If this option is absent,
ip

lists all entries except for
none

and
noarp.



 

ip neighbour flush – flush neighbour entries

This command flushes neighbour tables, selecting
entries to flush by some criteria.


This command has the same arguments as
show.

The differences are that it does not run when no arguments are given,
and that the default neighbour states to be flushed do not include
permanent

and
noarp.


With the
-statistics

option, the command becomes verbose. It prints out the number of
deleted neighbours and the number of rounds made to flush the
neighbour table. If the option is given
twice,
ip neigh flush

also dumps all the deleted neighbours.


 

ip route – routing table management

Manipulate route entries in the kernel routing tables keep
information about paths to other networked nodes.


Route types:

unicast

– the route entry describes real paths to the destinations covered
by the route prefix.



unreachable

– these destinations are unreachable. Packets are discarded and the
ICMP message
host unreachable

is generated.
The local senders get an
EHOSTUNREACH

error.



blackhole

– these destinations are unreachable. Packets are discarded silently.
The local senders get an
EINVAL

error.



prohibit

– these destinations are unreachable. Packets are discarded and the
ICMP message
communication administratively prohibited

is generated. The local senders get an
EACCES

error.



local

– the destinations are assigned to this host. The packets are looped
back and delivered locally.



broadcast

– the destinations are broadcast addresses. The packets are sent as
link broadcasts.



throw

– a special control route used together with policy rules. If such a
route is selected, lookup in this table is terminated pretending that
no route was found. Without policy routing it is equivalent to the
absence of the route in the routing table. The packets are dropped
and the ICMP message
net unreachable

is generated. The local senders get an
ENETUNREACH

error.



nat

– a special NAT route. Destinations covered by the prefix
are considered to be dummy (or external) addresses which require translation
to real (or internal) ones before forwarding. The addresses to translate to
are selected with the attribute
Warning:

Route NAT is no longer supported in Linux 2.6.



via.


anycast

not implemented

the destinations are
anycast

addresses assigned to this host. They are mainly equivalent
to
local

with one difference: such addresses are invalid when used
as the source address of any packet.



multicast

– a special type used for multicast routing. It is not present in
normal routing tables.


Route tables:

Linux-2.x can pack routes into several routing
tables identified by a number in the range from 1 to 255 or by
name from the file
/etc/iproute2/rt_tables

By default all normal routes are inserted into the
main

table (ID 254) and the kernel only uses this table when calculating routes.



Actually, one other table always exists, which is invisible but
even more important. It is the
local

table (ID 255). This table
consists of routes for local and broadcast addresses. The kernel maintains
this table automatically and the administrator usually need not modify it
or even look at it.


The multiple routing tables enter the game when
policy routing

is used.


 

ip route add – add new route

 

ip route change – change route

 

ip route replace – change or add new one



to TYPE PREFIX (default)


the destination prefix of the route. If
TYPE

is omitted,
ip

assumes type
unicast.

Other values of
TYPE

are listed above.
PREFIX

is an IP or IPv6 address optionally followed by a slash and the
prefix length. If the length of the prefix is missing,
ip

assumes a full-length host route. There is also a special
PREFIX

default

– which is equivalent to IP
0/0

or to IPv6
::/0.


tos TOS


dsfield TOS


the Type Of Service (TOS) key. This key has no associated mask and
the longest match is understood as: First, compare the TOS
of the route and of the packet. If they are not equal, then the packet
may still match a route with a zero TOS.
TOS

is either an 8 bit hexadecimal number or an identifier
from
/etc/iproute2/rt_dsfield.


metric NUMBER


preference NUMBER


the preference value of the route.
NUMBER

is an arbitrary 32bit number.


table TABLEID


the table to add this route to.
TABLEID

may be a number or a string from the file
/etc/iproute2/rt_tables.

If this parameter is omitted,
ip

assumes the
main

table, with the exception of
local , broadcast and nat

routes, which are put into the
local

table by default.


dev NAME


the output device name.


via ADDRESS


the address of the nexthop router. Actually, the sense of this field
depends on the route type. For normal
unicast

routes it is either the true next hop router or, if it is a direct
route installed in BSD compatibility mode, it can be a local address
of the interface. For NAT routes it is the first address of the block
of translated IP destinations.


src ADDRESS


the source address to prefer when sending to the destinations
covered by the route prefix.


realm REALMID


the realm to which this route is assigned.
REALMID

may be a number or a string from the file
/etc/iproute2/rt_realms.


mtu MTU


mtu lock MTU


the MTU along the path to the destination. If the modifier
lock

is not used, the MTU may be updated by the kernel due to
Path MTU Discovery. If the modifier
lock

is used, no path MTU discovery will be tried, all packets
will be sent without the DF bit in IPv4 case or fragmented
to MTU for IPv6.


window NUMBER


the maximal window for TCP to advertise to these destinations,
measured in bytes. It limits maximal data bursts that our TCP
peers are allowed to send to us.


rtt TIME


the initial RTT (‘Round Trip Time’) estimate. If no suffix is
specified the units are raw values passed directly to the
routing code to maintain compatability with previous releases.
Otherwise if a suffix of s, sec or secs is used to specify
seconds and ms, msec or msecs to specify milliseconds.


rttvar TIME (2.3.15+ only)


the initial RTT variance estimate. Values are specified as with
rtt

above.


rto_min TIME (2.6.23+ only)


the minimum TCP Retransmission TimeOut to use when communicating with this
destination. Values are specified as with
rtt

above.


ssthresh NUMBER (2.3.15+ only)


an estimate for the initial slow start threshold.


cwnd NUMBER (2.3.15+ only)


the clamp for congestion window. It is ignored if the
lock

flag is not used.


initcwnd NUMBER


the maximum initial congestion window (cwnd) size in MSS of a
TCP connection.


initrwnd NUMBER (2.6.33+ only)


the initial receive window size for connections to this destination.
Actual window size is this value multiplied by the MSS of the connection.
The default value is zero, meaning to use Slow Start value.


advmss NUMBER (2.3.15+ only)


the MSS (‘Maximal Segment Size’) to advertise to these
destinations when establishing TCP connections. If it is not given,
Linux uses a default value calculated from the first hop device MTU.
(If the path to these destination is asymmetric, this guess may be wrong.)


reordering NUMBER (2.3.15+ only)


Maximal reordering on the path to this destination.
If it is not given, Linux uses the value selected with
sysctl

variable
net/ipv4/tcp_reordering.


nexthop NEXTHOP


the nexthop of a multipath route.
NEXTHOP

is a complex value with its own syntax similar to the top level
argument lists:

via ADDRESS

– is the nexthop router.



dev NAME

– is the output device.



weight NUMBER

– is a weight for this element of a multipath
route reflecting its relative bandwidth or quality.


scope SCOPE_VAL


the scope of the destinations covered by the route prefix.
SCOPE_VAL

may be a number or a string from the file
/etc/iproute2/rt_scopes.

If this parameter is omitted,
ip

assumes scope
global

for all gatewayed
unicast

routes, scope
link

for direct
unicast and broadcast

routes and scope
host for local

routes.


protocol RTPROTO


the routing protocol identifier of this route.
RTPROTO

may be a number or a string from the file
/etc/iproute2/rt_protos.

If the routing protocol ID is not given,
ip assumes protocol

boot

(i.e. it assumes the route was added by someone who doesn’t
understand what they are doing). Several protocol values have
a fixed interpretation.
Namely:

redirect

– the route was installed due to an ICMP redirect.



kernel

– the route was installed by the kernel during autoconfiguration.



boot

– the route was installed during the bootup sequence.
If a routing daemon starts, it will purge all of them.



static

– the route was installed by the administrator
to override dynamic routing. Routing daemon will respect them
and, probably, even advertise them to its peers.



ra

– the route was installed by Router Discovery protocol.



The rest of the values are not reserved and the administrator is free
to assign (or not to assign) protocol tags.


onlink


pretend that the nexthop is directly attached to this link,
even if it does not match any interface prefix.


equalize


allow packet by packet randomization on multipath routes.
Without this modifier, the route will be frozen to one selected
nexthop, so that load splitting will only occur on per-flow base.
equalize

only works if the kernel is patched.



 

ip route delete – delete route


ip route del

has the same arguments as
ip route add,

but their semantics are a bit different.


Key values
(to, tos, preference and table)

select the route to delete. If optional attributes are present,
ip

verifies that they coincide with the attributes of the route to delete.
If no route with the given key and attributes was found,
ip route del

fails.


 

ip route show – list routes

the command displays the contents of the routing tables or the route(s)
selected by some criteria.



to SELECTOR (default)


only select routes from the given range of destinations.
SELECTOR

consists of an optional modifier
(root, match or exact)

and a prefix.
root PREFIX

selects routes with prefixes not shorter than
PREFIX.

F.e.
root 0/0

selects the entire routing table.
match PREFIX

selects routes with prefixes not longer than
PREFIX.

F.e.
match 10.0/16

selects
10.0/16,

10/8 and 0/0,

but it does not select
10.1/16 and 10.0.0/24.

And
exact PREFIX

(or just
PREFIX)

selects routes with this exact prefix. If neither of these options
are present,
ip

assumes
root 0/0

i.e. it lists the entire table.


tos TOS


dsfield TOS

only select routes with the given TOS.


table TABLEID


show the routes from this table(s). The default setting is to show
tablemain.

TABLEID

may either be the ID of a real table or one of the special values:

all

– list all of the tables.


cache

– dump the routing cache.


cloned


cached


list cloned routes i.e. routes which were dynamically forked from
other routes because some route attribute (f.e. MTU) was updated.
Actually, it is equivalent to
table cache.


from SELECTOR


the same syntax as for
to,

but it binds the source address range rather than destinations.
Note that the
from

option only works with cloned routes.


protocol RTPROTO


only list routes of this protocol.


scope SCOPE_VAL


only list routes with this scope.


type TYPE


only list routes of this type.


dev NAME


only list routes going via this device.


via PREFIX


only list routes going via the nexthop routers selected by
PREFIX.


src PREFIX


only list routes with preferred source addresses selected
by
PREFIX.


realm REALMID


realms FROMREALM/TOREALM


only list routes with these realms.



 

ip route flush – flush routing tables

this command flushes routes selected by some criteria.



The arguments have the same syntax and semantics as the arguments of
ip route show,

but routing tables are not listed but purged. The only difference is
the default action:
show

dumps all the IP main routing table but
flush

prints the helper page.



With the
-statistics

option, the command becomes verbose. It prints out the number of
deleted routes and the number of rounds made to flush the routing
table. If the option is given
twice,
ip route flush

also dumps all the deleted routes in the format described in the
previous subsection.


 

ip route get – get a single route

this command gets a single route to a destination and prints its
contents exactly as the kernel sees it.



to ADDRESS (default)


the destination address.


from ADDRESS


the source address.


tos TOS


dsfield TOS


the Type Of Service.


iif NAME


the device from which this packet is expected to arrive.


oif NAME


force the output device on which this packet will be routed.


connected


if no source address
(option from)

was given, relookup the route with the source set to the preferred
address received from the first lookup.
If policy routing is used, it may be a different route.



Note that this operation is not equivalent to
ip route show.

show

shows existing routes.
get

resolves them and creates new clones if necessary. Essentially,
get

is equivalent to sending a packet along this path.
If the
iif

argument is not given, the kernel creates a route
to output packets towards the requested destination.
This is equivalent to pinging the destination
with a subsequent
ip route ls cache,

however, no packets are actually sent. With the
iif

argument, the kernel pretends that a packet arrived from this interface
and searches for a path to forward the packet.


 

ip rule – routing policy database management


Rules

in the routing policy database control the route selection algorithm.


Classic routing algorithms used in the Internet make routing decisions
based only on the destination address of packets (and in theory,
but not in practice, on the TOS field).


In some circumstances we want to route packets differently depending not only
on destination addresses, but also on other packet fields: source address,
IP protocol, transport protocol ports or even packet payload.
This task is called ‘policy routing’.


To solve this task, the conventional destination based routing table, ordered
according to the longest match rule, is replaced with a ‘routing policy
database’ (or RPDB), which selects routes by executing some set of rules.


Each policy routing rule consists of a
selector

and an
action predicate.

The RPDB is scanned in the order of increasing priority. The selector
of each rule is applied to {source address, destination address, incoming
interface, tos, fwmark} and, if the selector matches the packet,
the action is performed. The action predicate may return with success.
In this case, it will either give a route or failure indication
and the RPDB lookup is terminated. Otherwise, the RPDB program
continues on the next rule.


Semantically, natural action is to select the nexthop and the output device.


At startup time the kernel configures the default RPDB consisting of three
rules:



1.

Priority: 0, Selector: match anything, Action: lookup routing
table
local

(ID 255).
The
local

table is a special routing table containing
high priority control routes for local and broadcast addresses.


Rule 0 is special. It cannot be deleted or overridden.


2.

Priority: 32766, Selector: match anything, Action: lookup routing
table
main

(ID 254).
The
main

table is the normal routing table containing all non-policy
routes. This rule may be deleted and/or overridden with other
ones by the administrator.


3.

Priority: 32767, Selector: match anything, Action: lookup routing
table
default

(ID 253).
The
default

table is empty. It is reserved for some post-processing if no previous
default rules selected the packet.
This rule may also be deleted.



Each RPDB entry has additional
attributes. F.e. each rule has a pointer to some routing
table. NAT and masquerading rules have an attribute to select new IP
address to translate/masquerade. Besides that, rules have some
optional attributes, which routes have, namely
realms.

These values do not override those contained in the routing tables. They
are only used if the route did not select any attributes.



The RPDB may contain rules of the following types:

unicast

– the rule prescribes to return the route found
in the routing table referenced by the rule.


blackhole

– the rule prescribes to silently drop the packet.


unreachable

– the rule prescribes to generate a ‘Network is unreachable’ error.


prohibit

– the rule prescribes to generate ‘Communication is administratively
prohibited’ error.


nat

– the rule prescribes to translate the source address
of the IP packet into some other value.


 

ip rule add – insert a new rule

 

ip rule delete – delete a rule



type TYPE (default)


the type of this rule. The list of valid types was given in the previous
subsection.


from PREFIX


select the source prefix to match.


to PREFIX


select the destination prefix to match.


iif NAME


select the incoming device to match. If the interface is loopback,
the rule only matches packets originating from this host. This means
that you may create separate routing tables for forwarded and local
packets and, hence, completely segregate them.


tos TOS


dsfield TOS


select the TOS value to match.


fwmark MARK


select the
fwmark

value to match.


priority PREFERENCE


the priority of this rule. Each rule should have an explicitly
set
unique

priority value.
The options preference and order are synonyms with priority.


table TABLEID


the routing table identifier to lookup if the rule selector matches.
It is also possible to use lookup instead of table.


realms FROM/TO


Realms to select if the rule matched and the routing table lookup
succeeded. Realm
TO

is only used if the route did not select any realm.


nat ADDRESS


The base of the IP address block to translate (for source addresses).
The
ADDRESS

may be either the start of the block of NAT addresses (selected by NAT
routes) or a local host address (or even zero).
In the last case the router does not translate the packets, but
masquerades them to this address.
Using map-to instead of nat means the same thing.


Warning:

Changes to the RPDB made with these commands do not become active
immediately. It is assumed that after a script finishes a batch of
updates, it flushes the routing cache with
ip route flush cache.



 

ip rule flush – also dumps all the deleted rules.

This command has no arguments.


 

ip rule show – list rules

This command has no arguments.
The options list or lst are synonyms with show.


 

ip maddress – multicast addresses management


maddress

objects are multicast addresses.


 

ip maddress show – list multicast addresses



dev NAME (default)


the device name.



 

ip maddress add – add a multicast address

 

ip maddress delete – delete a multicast address

these commands attach/detach a static link layer multicast address
to listen on the interface.
Note that it is impossible to join protocol multicast groups
statically. This command only manages link layer addresses.



address LLADDRESS (default)


the link layer multicast address.


dev NAME


the device to join/leave this multicast address.



 

ip mroute – multicast routing cache management

mroute

objects are multicast routing cache entries created by a user level
mrouting daemon (f.e.
pimd

or
mrouted

).


Due to the limitations of the current interface to the multicast routing
engine, it is impossible to change
mroute

objects administratively, so we may only display them. This limitation
will be removed in the future.


 

ip mroute show – list mroute cache entries



to PREFIX (default)


the prefix selecting the destination multicast addresses to list.


iif NAME


the interface on which multicast packets are received.


from PREFIX


the prefix selecting the IP source addresses of the multicast route.



 

ip tunnel – tunnel configuration

tunnel

objects are tunnels, encapsulating packets in IP packets and then
sending them over the IP infrastructure.
The encapulating (or outer) address family is specified by the
-f

option. The default is IPv4.


 

ip tunnel add – add a new tunnel

 

ip tunnel change – change an existing tunnel

 

ip tunnel delete – destroy a tunnel



name NAME (default)


select the tunnel device name.


mode MODE


set the tunnel mode. Available modes depend on the encapsulating address family.

Modes for IPv4 encapsulation available:
ipip, sit, isatap and gre.


Modes for IPv6 encapsulation available:
ip6ip6, ipip6 and any.


remote ADDRESS


set the remote endpoint of the tunnel.


local ADDRESS


set the fixed local address for tunneled packets.
It must be an address on another interface of this host.


ttl N


set a fixed TTL
N

on tunneled packets.
N

is a number in the range 1–255. 0 is a special value
meaning that packets inherit the TTL value.
The default value for IPv4 tunnels is:
inherit.

The default value for IPv6 tunnels is:
64.



tos T


dsfield T


tclass T


set a fixed TOS (or traffic class in IPv6)
T

on tunneled packets.
The default value is:
inherit.


dev NAME


bind the tunnel to the device
NAME

so that tunneled packets will only be routed via this device and will
not be able to escape to another device when the route to endpoint
changes.


nopmtudisc


disable Path MTU Discovery on this tunnel.
It is enabled by default. Note that a fixed ttl is incompatible
with this option: tunnelling with a fixed ttl always makes pmtu
discovery.


key K


ikey K


okey K


( only GRE tunnels )

use keyed GRE with key
K. K

is either a number or an IP address-like dotted quad.
The
key

parameter sets the key to use in both directions.
The
ikey and okey

parameters set different keys for input and output.


csum, icsum, ocsum


( only GRE tunnels )

generate/require checksums for tunneled packets.
The
ocsum

flag calculates checksums for outgoing packets.
The
icsum

flag requires that all input packets have the correct
checksum. The
csum

flag is equivalent to the combination
icsum ocsum.


seq, iseq, oseq


( only GRE tunnels )

serialize packets.
The
oseq

flag enables sequencing of outgoing packets.
The
iseq

flag requires that all input packets are serialized.
The
seq

flag is equivalent to the combination
iseq oseq.

It isn’t work. Don’t use it.


dscp inherit


( only IPv6 tunnels )

Inherit DS field between inner and outer header.


encaplim ELIM


( only IPv6 tunnels )

set a fixed encapsulation limit. Default is 4.


flowlabel FLOWLABEL


( only IPv6 tunnels )

set a fixed flowlabel.



 

ip tunnel prl – potential router list (ISATAP only)



dev NAME


mandatory device name.


prl-default ADDR


prl-nodefault ADDR


prl-delete ADDR


Add or delete ADDR

as a potential router or default router.



 

ip tunnel show – list tunnels

This command has no arguments.


 

ip monitor and rtmon – state monitoring


The
ip

utility can monitor the state of devices, addresses
and routes continuously. This option has a slightly different format.
Namely, the
monitor

command is the first in the command line and then the object list follows:


ip monitor [ all |

LISTofOBJECTS ]


OBJECT-LIST

is the list of object types that we want to monitor.
It may contain
link, address and route.

If no
file

argument is given,
ip

opens RTNETLINK, listens on it and dumps state changes in the format
described in previous sections.


If a file name is given, it does not listen on RTNETLINK,
but opens the file containing RTNETLINK messages saved in binary format
and dumps them. Such a history file can be generated with the
rtmon

utility. This utility has a command line syntax similar to
ip monitor.

Ideally,
rtmon

should be started before the first network configuration command
is issued. F.e. if you insert:

rtmon file /var/log/rtmon.log


in a startup script, you will be able to view the full history
later.


Certainly, it is possible to start
rtmon

at any time.
It prepends the history with the state snapshot dumped at the moment
of starting.


 

ip xfrm – setting xfrm

xfrm is an IP framework, which can transform format of the datagrams,

i.e. encrypt the packets with some algorithm. xfrm policy and xfrm state
are associated through templates
TMPL_LIST.

This framework is used as a part of IPsec protocol.


 

ip xfrm state add – add new state into xfrm


 

ip xfrm state update – update existing xfrm state


 

ip xfrm state allocspi – allocate SPI value



MODE


is set as default to
transport,

but it could be set to
tunnel,ro or beet.


FLAG-LIST


contains one or more flags.


FLAG


could be set to
noecn, decap-dscp or wildrecv.


ENCAP


encapsulation is set to encapsulation type
ENCAP-TYPE, source port SPORT, destination port DPORT and OADDR.


ENCAP-TYPE


could be set to
espinudp or espinudp-nonike.


ALGO-LIST


contains one or more algorithms
ALGO

which depend on the type of algorithm set by
ALGO_TYPE.

It can be used these algoritms
enc, auth or comp.



 

ip xfrm policy add – add a new policy


 

ip xfrm policy update – update an existing policy


 

ip xfrm policy delete – delete existing policy


 

ip xfrm policy get – get existing policy


 

ip xfrm policy deleteall – delete all existing xfrm policy


 

ip xfrm policy list – print out the list of xfrm policy


 

ip xfrm policy flush – flush policies

It can be flush
all

policies or only those specified with
ptype.



dir DIR


directory could be one of these:
inp, out or fwd.


SELECTOR


selects for which addresses will be set up the policy. The selector
is defined by source and destination address.


UPSPEC


is defined by source port
sport,

destination port
dport, type

as number and
code

also number.


dev DEV


specify network device.


index INDEX


the number of indexed policy.


ptype PTYPE


type is set as default on
main,

could be switch on
sub.


action ACTION


is set as default on
allow.

It could be switch on
block.


priority PRIORITY


priority is a number. Default priority is set on zero.


LIMIT-LIST


limits are set in seconds, bytes or numbers of packets.


TMPL-LIST


template list is based on
ID,

mode, reqid and level.


ID


is specified by source address, destination address,
proto

and value of
spi.


XFRM_PROTO


values:
esp, ah, comp, route2 or hao.


MODE


is set as default on
transport,

but it could be set on
tunnel or beet.


LEVEL


is set as default on
required

and the other choice is
use.


UPSPEC


is specified by
sport,

dport, type

and
code

(NUMBER).



 

ip xfrm monitor – is used for listing all objects or defined group of them.

The
xfrm monitor

can monitor the policies for all objects or defined group of them.


 

ip token

IPv6 tokenized interface identifer support is used for assigning well-known
host-part addresses to nodes whilst still obtaining a global network prefix
from Router advertisements. The primary target for tokenized identifiers are
server platforms where addresses are usually manually configured, rather than
using DHCPv6 or SLAAC. By using tokenized identifiers, hosts can still
determine their network prefix by use of SLAAC, but more readily be
automatically renumbered should their network prefix change [1]. Tokenized
IPv6 Identifiers are described in the draft
[1]: <draft-chown-6man-tokenised-ipv6-identifiers-02>.


 

ip token set – set an interface token

set the interface token to the kernel. Once a token is set, it cannot be
removed from the interface, only overwritten.


TOKEN


the interface identifer token address.
dev DEV


the networking interface.



 

ip token get – get the interface token from the kernel

show a tokenized interface identifer of a particular networking device.
Arguments:

coincide with the arguments of
ip token set

but the
TOKEN

must be left out.
 

ip token list – list all interface tokens

list all tokenized interface identifers for the networking interfaces from
the kernel.


 

HISTORY

ip

was written by Alexey N. Kuznetsov and added in Linux 2.2.
 

SEE ALSO

tc(8)


IP Command reference ip-cref.ps


IP tunnels ip-cref.ps


User documentation at http://lartc.org/, but please direct bugreports and patches to: <[email protected]>


 

AUTHOR

Original Manpage by Michail Litvak <[email protected]>



 

Index



NAME

SYNOPSIS

OPTIONS

IP – COMMAND SYNTAX


OBJECT


COMMAND



ip link – network device configuration


ip link set – change device attributes

ip link show – display device attributes


ip address – protocol address management.


ip address add – add new protocol address.

ip address delete – delete protocol address

ip address show – look at protocol addresses

ip address flush – flush protocol addresses


ip addrlabel – protocol address label management.


ip addrlabel add – add an address label

ip addrlabel del – delete an address label

ip addrlabel list – list address labels

ip addrlabel flush – flush address labels


ip neighbour – neighbour/arp tables management.


ip neighbour add – add a new neighbour entry

ip neighbour change – change an existing entry

ip neighbour replace – add a new entry or change an existing one

ip neighbour delete – delete a neighbour entry

ip neighbour show – list neighbour entries

ip neighbour flush – flush neighbour entries


ip route – routing table management


ip route add – add new route

ip route change – change route

ip route replace – change or add new one

ip route delete – delete route

ip route show – list routes

ip route flush – flush routing tables

ip route get – get a single route


ip rule – routing policy database management


ip rule add – insert a new rule

ip rule delete – delete a rule

ip rule flush – also dumps all the deleted rules.

ip rule show – list rules


ip maddress – multicast addresses management


ip maddress show – list multicast addresses

ip maddress add – add a multicast address

ip maddress delete – delete a multicast address


ip mroute – multicast routing cache management


ip mroute show – list mroute cache entries


ip tunnel – tunnel configuration


ip tunnel add – add a new tunnel

ip tunnel change – change an existing tunnel

ip tunnel delete – destroy a tunnel

ip tunnel prl – potential router list (ISATAP only)

ip tunnel show – list tunnels


ip monitor and rtmon – state monitoring

ip xfrm – setting xfrm


ip xfrm state add – add new state into xfrm

ip xfrm state update – update existing xfrm state

ip xfrm state allocspi – allocate SPI value

ip xfrm policy add – add a new policy

ip xfrm policy update – update an existing policy

ip xfrm policy delete – delete existing policy

ip xfrm policy get – get existing policy

ip xfrm policy deleteall – delete all existing xfrm policy

ip xfrm policy list – print out the list of xfrm policy

ip xfrm policy flush – flush policies

ip xfrm monitor – is used for listing all objects or defined group of them.


ip token


ip token set – set an interface token

ip token get – get the interface token from the kernel

ip token list – list all interface tokens


HISTORY

SEE ALSO

AUTHOR



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