Man Linux: Main Page and Category List


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


       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 add link DEVICE [ name ] NAME
               [ txqueuelen PACKETS ]
               [ address LLADDR ] [ broadcast LLADDR ]
               [ mtu MTU ]
               typeTYPE [ ARGS ]

       TYPE := [ vlan | maclan | can ]

       ip link delete DEVICE typeTYPE [ ARGS ]

       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 := [ permanent | dynamic | secondary | primary | tentative |
               deprecated | dadfailed | temporary ]

       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 ]


       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 ] [ ssthresh REALM ] [
               realms REALM ] [ rto_min TIME ] [ initcwnd NUMBER ] [ initrwnd
               NUMBER ]

       TYPE := [ unicast | local | broadcast | multicast | throw | unreachable
               | prohibit | blackhole | nat ]

       TABLE_ID := [ local| main | default | all | NUMBER ]

       SCOPE := [ host | link | global | NUMBER ]

       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] ] [ iif STRING ] [ oif 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|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 ] (default=transport)


       FLAG :=  [ noecn | decap-dscp | wildrecv ]


       ENCAP-TYPE := espinudp  | espinudp-nonike

       ALGO-LIST := [ ALGO-LIST ] | [ ALGO ]


       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 ]


       -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.


       link   - network device.

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

              - label configuration for protocol address selection.

              - ARP or NDISC cache entry.

       route  - routing table entry.

       rule   - rule in routing policy database.

              - 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.

       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 add - add virtual link
       link DEVICE
              specifies the physical device to act operate on.

              NAME specifies the name of the new virtual device.

              TYPE specifies the type of the new device.

              Link types:

                      vlan - 802.1q tagged virrtual LAN interface

                      macvlan  -  virtual interface base on link layer address

                      can - Controller Area Network interface

   ip link delete - delete virtual link
       DEVICE specifies the virtual  device to act operate on.  TYPE specifies
       the type of the device.

       dev DEVICE
              specifies the physical device to act operate on.

   ip link set - change device attributes
       dev DEVICE
              DEVICE  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

       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

   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

       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)

              (IPv6 only) only  list  addresses  which  have  not  yet  passed
              duplicate address detection.

              (IPv6 only) only list deprecated addresses.

              (IPv6  only)  only  list  addresses  which have failed duplicate
              address detection.

              (IPv6 only) only list temporary 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

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

   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

       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

               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.


               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 2^31 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.  Values (0, 253, 254, and  255)  are  reserved  for
       built-in use.

       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

       metric NUMBER

       preference NUMBER
              the preference value of the route.  NUMBER is an arbitrary 32bit

       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;  ms, msec or msecs to specify milliseconds; us, usec or
              usecs to specify microseconds; ns,  nsec  or  nsecs  to  specify
              nanoseconds;  j,  hz or jiffies to specify jiffies, the value is
              converted to what the routing code expects.

       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 (2.5.70+ only)
              the initial congestion  window  size  for  connections  to  this
              destination.  Actual window size is this value multiplied by the
              MSS (‘‘Maximal Segment Size’’) for same connection. The  default
              is zero, meaning to use the values specified in RFC2414.

       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

       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

       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

                      kernel - the route was installed by  the  kernel  during

                      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

              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.

   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.


       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

       src PREFIX
              only  list  routes  with  preferred source addresses selected by

       realm REALMID

              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

   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.

              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

       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

       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

       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

       oif NAME
              select the outgoing device to match.  The outgoing interface  is
              only  available  for packets originating from local sockets that
              are bound to a device.

       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

       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

       iif NAME
              the interface on which multicast packets are received.

       from PREFIX
              the prefix selecting the IP source addresses  of  the  multicast

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

   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
              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.

              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 isnt work. Dont use it.

       dscp inherit
              ( only IPv6 tunnels ) Inherit DS field between inner  and  outer

       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.

              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.

              could be set to espinudp or espinudp-nonike.

              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.

              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.

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

              template list is based on ID, mode, reqid and level.

       ID     is specified by source address, destination address,  proto  and
              value of spi.

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

       MODE   is set as default on transport, but it could be set on tunnel or

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


       IP Command reference
       IP tunnels
       User documentation at, but please  direct  bugreports
       and patches to: <>


       Original Manpage  by Michail Litvak <>