ip - Unix, Linux Command

---

---

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 } |
allmulti { on | off } |
dynamic { on | off } |
multicast { on | off } |
txqueuelen PACKETS |
name NEWNAME |
address LLADDR | broadcast LLADDR |
mtu MTU }

   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 ]

   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 ] [ 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 } [ NAME ]
[ mode { ipip | gre | sit } ]
[ remote ADDR ] [ local ADDR ]
[ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ] ]
[ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ]
[ dev PHYS_DEV ]

   ADDR := { IP_ADDRESS | any }

   TOS := { NUMBER | inherit }

   TTL := { 1..255 | inherit }

   KEY := { DOTTED_QUAD | NUMBER }

   TIME := NUMBER[s|ms|us|ns|j]

   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 ]

   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 ]

   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 ]

   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 ]

   LEVEL := [ required | use ]

   ip xfrm monitor [ all | LISTofOBJECTS ]

OPTIONS

IP - COMMAND SYNTAX

OBJECT

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

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

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.

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

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.

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 commoand 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.

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.

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

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.

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.

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:

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

ip rule flush - also dumps all the deleted rules.

This command has no arguments.

ip rule show - list rules

This command has no arguments.

ip maddress - multicast addresses management

maddress objects are multicast addresses.

ip maddress show - list multicast addresses

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.

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

ip tunnel - tunnel configuration

tunnel objects are tunnels, encapsulating packets in IPv4 packets and then sending them over the IP infrastructure.

ip tunnel add - add a new tunnel

ip tunnel change - change an existing tunnel

ip tunnel delete - destroy a tunnel

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

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.

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.

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

AUTHOR

Original Manpage by Michail Litvak <[email protected]>