IP-ROUTE(8) Linux IP-ROUTE(8)
NAME
ip-route - routing table management
SYNOPSIS
ip [ ip-OPTIONS ] route { COMMAND | help }
ip route { show | flush } SELECTOR
ip route save SELECTOR
ip route restore
ip route get ROUTE_GET_FLAGS [ to ] ADDRESS [ from ADDRESS iif STRING ]
[ oif STRING ] [ mark MARK ] [ tos TOS ] [ vrf NAME ] [ ipproto
PROTOCOL ] [ sport NUMBER ] [ dport NUMBER ] [ as ADDRESS ] [
flowlabel FLOWLABEL ]
ip route { add | del | change | append | replace } ROUTE
SELECTOR := [ root PREFIX ] [ match PREFIX ] [ exact PREFIX ] [ table
TABLE_ID ] [ vrf NAME ] [ proto RTPROTO ] [ type TYPE ] [ scope
SCOPE ]
ROUTE := NODE_SPEC [ INFO_SPEC ]
NODE_SPEC := [ TYPE ] PREFIX [ tos TOS ] [ table TABLE_ID ] [ proto RT-
PROTO ] [ scope SCOPE ] [ metric METRIC ] [ ttl-propagate { en-
abled | disabled } ]
INFO_SPEC := { NH | nhid ID } OPTIONS FLAGS [ nexthop NH ] ...
NH := [ encap ENCAP ] [ via [ FAMILY ] ADDRESS ] [ dev STRING ] [ weight
NUMBER ] NHFLAGS
FAMILY := [ inet | inet6 | mpls | bridge | link ]
OPTIONS := FLAGS [ mtu NUMBER ] [ advmss NUMBER ] [ as [ to ] ADDRESS ]
rtt TIME ] [ rttvar TIME ] [ reordering NUMBER ] [ window NUMBER
] [ cwnd NUMBER ] [ ssthresh NUMBER ] [ realms REALM ] [ rto_min
TIME ] [ initcwnd NUMBER ] [ initrwnd NUMBER ] [ features FEA-
TURES ] [ quickack BOOL ] [ congctl NAME ] [ pref PREF ] [ ex-
pires TIME ] [ fastopen_no_cookie BOOL ]
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 ]
FEATURES := [ ecn | ]
PREF := [ low | medium | high ]
ENCAP := [ ENCAP_MPLS | ENCAP_IP | ENCAP_BPF | ENCAP_SEG6 | EN-
CAP_SEG6LOCAL | ENCAP_IOAM6 ]
ENCAP_MPLS := mpls [ LABEL ] [ ttl TTL ]
ENCAP_IP := ip id TUNNEL_ID dst REMOTE_IP [ src SRC ] [ tos TOS ] [ ttl
TTL ] [ key ] [ csum ] [ seq ] [ GENEVE_OPTS | VXLAN_OPTS |
ERSPAN_OPTS ]
ENCAP_BPF := bpf [ in PROG ] [ out PROG ] [ xmit PROG ] [ headroom SIZE
]
ENCAP_SEG6 := seg6 mode [ encap | encap.red | inline | l2encap | l2en-
cap.red ] segs SEGMENTS [ hmac KEYID ]
ENCAP_SEG6LOCAL := seg6local action SEG6_ACTION [ SEG6_ACTION_PARAM ] [
count ]
ENCAP_IOAM6 := ioam6 [ freq K/N ] mode [ inline | encap | auto ] [ tun-
src ADDRESS ] [ tundst ADDRESS ] trace prealloc type
IOAM6_TRACE_TYPE ns IOAM6_NAMESPACE size IOAM6_TRACE_SIZE
ROUTE_GET_FLAGS := ROUTE_GET_FLAG [ ROUTE_GET_FLAGS ]
ROUTE_GET_FLAG := [ connected | fibmatch | notify ]
DESCRIPTION
ip route is used to manipulate entries in the kernel routing tables.
Route types:
unicast - the route entry describes real paths to the destina-
tions 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 dis-
carded silently. The local senders get an EINVAL error.
prohibit - these destinations are unreachable. Packets are dis-
carded and the ICMP message communication administratively pro-
hibited 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 pack-
ets 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 gen-
erated. 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 via.
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 2^32-1 or by name from
/usr/share/iproute2/rt_tables or /etc/iproute2/rt_tables (has precedence
if exists). By default all normal routes are inserted into the main ta-
ble (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 ta-
ble 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 fol-
lowed 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, com-
pare 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 /usr/share/iproute2/rt_dsfield or
/etc/iproute2/rt_dsfield (has precedence if exists).
metric NUMBER
preference NUMBER
the preference value of the route. NUMBER is an arbitrary
32bit number, where routes with lower values are pre-
ferred.
table TABLEID
the table to add this route to. TABLEID may be a number
or a string from /usr/share/iproute2/rt_tables or
/etc/iproute2/rt_tables (has precedence if exists). 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.
vrf NAME
the vrf name to add this route to. Implicitly means the
table associated with the VRF.
dev NAME
the output device name.
via [ FAMILY ] ADDRESS
the address of the nexthop router, in the address family
FAMILY. 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 destina-
tions covered by the route prefix.
realm REALMID
the realm to which this route is assigned. REALMID may be
a number or a string from /usr/share/iproute2/rt_realms or
/etc/iproute2/rt_realms (has precedence if exists).
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 destina-
tions, 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 compatibility with previous
releases. Otherwise if a suffix of s, sec or secs is used
to specify seconds and ms, msec or msecs to specify mil-
liseconds.
rttvar TIME (Linux 2.3.15+ only)
the initial RTT variance estimate. Values are specified as
with rtt above.
rto_min TIME (Linux 2.6.23+ only)
the minimum TCP Retransmission TimeOut to use when commu-
nicating with this destination. Values are specified as
with rtt above.
ssthresh NUMBER (Linux 2.3.15+ only)
an estimate for the initial slow start threshold.
cwnd NUMBER (Linux 2.3.15+ only)
the clamp for congestion window. It is ignored if the lock
flag is not used.
initcwnd NUMBER (Linux 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 (Linux 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.
features FEATURES (Linux3.18+only)
Enable or disable per-route features. Only available fea-
ture at this time is ecn to enable explicit congestion no-
tification when initiating connections to the given desti-
nation network. When responding to a connection request
from the given network, ecn will also be used even if the
net.ipv4.tcp_ecn sysctl is set to 0.
quickack BOOL (Linux 3.11+ only)
Enable or disable quick ack for connections to this desti-
nation.
fastopen_no_cookie BOOL (Linux 4.15+ only)
Enable TCP Fastopen without a cookie for connections to
this destination.
congctl NAME (Linux 3.20+ only)
congctl lock NAME (Linux 3.20+ only)
Sets a specific TCP congestion control algorithm only for
a given destination. If not specified, Linux keeps the
current global default TCP congestion control algorithm,
or the one set from the application. If the modifier lock
is not used, an application may nevertheless overwrite the
suggested congestion control algorithm for that destina-
tion. If the modifier lock is used, then an application is
not allowed to overwrite the specified congestion control
algorithm for that destination, thus it will be en-
forced/guaranteed to use the proposed algorithm.
advmss NUMBER (Linux 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 (Linux 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 argu-
ment lists:
via [ FAMILY ] 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.
The internal buffer used in iproute2 limits the maximum
number of nexthops that may be specified in one go. If
only ADDRESS is given, the current buffer size allows for
144 IPv6 nexthops and 253 IPv4 ones. For IPv4, this effec-
tively limits the number of nexthops possible per route.
With IPv6, further nexthops may be appended to the same
route via ip route append command.
scope SCOPE_VAL
the scope of the destinations covered by the route prefix.
SCOPE_VAL may be a number or a string from
/usr/share/iproute2/rt_scopes or /etc/iproute2/rt_scopes
(has precedence if exists). 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
/usr/share/iproute2/rt_protos or /etc/iproute2/rt_protos
(has precedence if exists). 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 in-
terpretation. 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 adminis-
trator 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 adminis-
trator 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.
pref PREF
the IPv6 route preference. PREF is a string specifying
the route preference as defined in RFC4191 for Router Dis-
covery messages. Namely:
low - the route has a lowest priority
medium - the route has a default priority
high - the route has a highest priority
nhid ID
use nexthop object with given id as nexthop specification.
encap ENCAPTYPE ENCAPHDR
attach tunnel encapsulation attributes to this route.
ENCAPTYPE is a string specifying the supported encapsula-
tion type. Namely:
mpls - encapsulation type MPLS
ip - IP encapsulation (Geneve, GRE, VXLAN, ...)
bpf - Execution of BPF program
seg6 - encapsulation type IPv6 Segment Routing
seg6local - local SRv6 segment processing
ioam6 - encapsulation type IPv6 IOAM
xfrm - encapsulation type XFRM
ENCAPHDR is a set of encapsulation attributes specific to
the ENCAPTYPE.
mpls
MPLSLABEL - mpls label stack with labels sepa-
rated by /
ttl TTL - TTL to use for MPLS header or 0 to in-
herit from IP header
ip
id TUNNEL_ID - Tunnel ID (for example VNI in
VXLAN tunnel)
dst REMOTE_IP - Outer header destination IP ad-
dress (IPv4 or IPv6)
src SRC - Outer header source IP address (IPv4
or IPv6)
tos TOS - Outer header TOS
ttl TTL - Outer header TTL
key - Outer header flags with key in GRE tunnel
csum - Outer header flags with csum in GRE tun-
nel
seq - Outer header flags with seq in GRE tunnel
GENEVE_OPTS - Specified in the form
CLASS:TYPE:DATA, where CLASS is represented as a
16bit hexadecimal value, TYPE as an 8bit hexa-
decimal value and DATA as a variable length
hexadecimal value. Additionally multiple options
may be listed using a comma delimiter.
VXLAN_OPTS - Specified in the form GBP, as a
32bit number. Multiple options is not supported.
ERSPAN_OPTS - Specified in the form VERSION:IN-
DEX:DIR:HWID, where VERSION is represented as a
8bit number, INDEX as an 32bit number, DIR and
HWID as a 8bit number. Multiple options is not
supported. Note INDEX is used when VERSION is 1,
and DIR and HWID are used when VERSION is 2.
bpf
in PROG - BPF program to execute for incoming
packets
out PROG - BPF program to execute for outgoing
packets
xmit PROG - BPF program to execute for transmit-
ted packets
headroom SIZE - Size of header BPF program will
attach (xmit)
seg6
mode inline - Directly insert Segment Routing
Header after IPv6 header
mode encap - Encapsulate packet in an outer IPv6
header with SRH
mode encap.red - Encapsulate packet in an outer
IPv6 header with SRH applying the reduced seg-
ment list. When there is only one segment and
the HMAC is not present, the SRH is omitted.
mode l2encap - Encapsulate ingress L2 frame
within an outer IPv6 header and SRH
mode l2encap.red - Encapsulate ingress L2 frame
within an outer IPv6 header and SRH applying the
reduced segment list. When there is only one
segment and the HMAC is not present, the SRH is
omitted.
SEGMENTS - List of comma-separated IPv6 ad-
dresses
KEYID - Numerical value in decimal representa-
tion. See ip-sr(8).
seg6local
SEG6_ACTION [ SEG6_ACTION_PARAM ] [ count ] -
Operation to perform on matching packets. The
optional count attribute is used to collect sta-
tistics on the processing of actions. Three
counters are implemented: 1) packets correctly
processed; 2) bytes correctly processed; 3)
packets that cause a processing error (i.e.,
missing SID List, wrong SID List, etc). To re-
trieve the counters related to an action use the
-s flag in the show command. The following ac-
tions are currently supported (Linux 4.14+
only).
End [ flavors FLAVORS ] - Regular SRv6 pro-
cessing as intermediate segment endpoint.
This action only accepts packets with a non-
zero Segments Left value. Other matching pack-
ets are dropped. The presence of flavors can
change the regular processing of an End behav-
ior according to the user-provided Flavor op-
erations and information carried in the
packet. See Flavors parameters section.
End.X nh6 NEXTHOP [ flavors FLAVORS ] - Regu-
lar SRv6 processing as intermediate segment
endpoint. Additionally, forward processed
packets to given next-hop. This action only
accepts packets with a non-zero Segments Left
value. Other matching packets are dropped. The
presence of flavors can change the regular
processing of an End.X behavior according to
the user-provided Flavor operations and infor-
mation carried in the packet. See Flavors pa-
rameters section.
End.DX6 nh6 NEXTHOP - Decapsulate inner IPv6
packet and forward it to the specified next-
hop. If the argument is set to ::, then the
next-hop is selected according to the local
selection rules. This action only accepts
packets with either a zero Segments Left value
or no SRH at all, and an inner IPv6 packet.
Other matching packets are dropped.
End.DT6 { table | vrftable } TABLEID - Decap-
sulate the inner IPv6 packet and forward it
according to the specified lookup table.
TABLEID is either a number or a string from
/usr/share/iproute2/rt_tables or
/etc/iproute2/rt_tables (has precedence if ex-
ists). If vrftable is used, the argument must
be a VRF device associated with the table id.
Moreover, the VRF table associated with the
table id must be configured with the VRF
strict mode turned on (net.vrf.strict_mode=1).
This action only accepts packets with either a
zero Segments Left value or no SRH at all, and
an inner IPv6 packet. Other matching packets
are dropped.
End.DT4 vrftable TABLEID - Decapsulate the in-
ner IPv4 packet and forward it according to
the specified lookup table. TABLEID is either
a number or a string from
/usr/share/iproute2/rt_tables or
/etc/iproute2/rt_tables (has precedence if ex-
ists). The argument must be a VRF device as-
sociated with the table id. Moreover, the VRF
table associated with the table id must be
configured with the VRF strict mode turned on
(net.vrf.strict_mode=1). This action only ac-
cepts packets with either a zero Segments Left
value or no SRH at all, and an inner IPv4
packet. Other matching packets are dropped.
End.DT46 vrftable TABLEID - Decapsulate the
inner IPv4 or IPv6 packet and forward it ac-
cording to the specified lookup table.
TABLEID is either a number or a string from
/usr/share/iproute2/rt_tables or
/etc/iproute2/rt_tables (has precedence if ex-
ists). The argument must be a VRF device as-
sociated with the table id. Moreover, the VRF
table associated with the table id must be
configured with the VRF strict mode turned on
(net.vrf.strict_mode=1). This action only ac-
cepts packets with either a zero Segments Left
value or no SRH at all, and an inner IPv4 or
IPv6 packet. Other matching packets are
dropped.
End.B6 srh segs SEGMENTS [ hmac KEYID ] - In-
sert the specified SRH immediately after the
IPv6 header, update the DA with the first seg-
ment of the newly inserted SRH, then forward
the resulting packet. The original SRH is not
modified. This action only accepts packets
with a non-zero Segments Left value. Other
matching packets are dropped.
End.B6.Encaps srh segs SEGMENTS [ hmac KEYID ]
- Regular SRv6 processing as intermediate seg-
ment endpoint. Additionally, encapsulate the
matching packet within an outer IPv6 header
followed by the specified SRH. The destination
address of the outer IPv6 header is set to the
first segment of the new SRH. The source ad-
dress is set as described in ip-sr(8).
Flavors parameters
The flavors represent additional operations
that can modify or extend a subset of the ex-
isting behaviors.
flavors OPERATION[,OPERATION] [ATTRIBUTES]
OPERATION := { psp | usp | usd | next-csid
}
ATTRIBUTES := { KEY VALUE } [ ATTRIBUTES ]
KEY := { lblen | nflen }
psp - The Penultimate Segment Pop (PSP)
copies the last SID from the SID List (car-
ried by the outermost SRH) into the IPv6
Destination Address (DA) and removes (i.e.
pops) the SRH from the IPv6 header. The PSP
operation takes place only at a penultimate
SR Segment Endpoint node (e.g., the Segment
Left must be one) and does not happen at
non-penultimate endpoint nodes. This flavor
is currently only supported by End behavior.
usp - Ultimate Segment Pop of the SRH (not
yet supported in kernel)
usd - Ultimate Segment Decapsulation (not
yet supported in kernel)
next-csid - The NEXT-C-SID mechanism offers
the possibility of encoding several SRv6
segments within a single 128 bit SID ad-
dress. The NEXT-C-SID flavor can be config-
ured to support user-provided Locator-Block
and Locator-Node Function lengths. If Loca-
tor-Block and/or Locator-Node Function
lengths are not provided by the user during
configuration of an SRv6 End behavior in-
stance with NEXT-C-SID flavor, the default
value is 32-bit for Locator-Block and 16-bit
for Locator-Node Function.
lblen VALUE - defines the Locator-Block
length for NEXT-C-SID flavor. The Locator-
Block length must be greater than 0 and
evenly divisible by 8. This attribute can be
used only with NEXT-C-SID flavor.
nflen VALUE - defines the Locator-Node Func-
tion length for NEXT-C-SID flavors. The Lo-
cator-Node Function length must be greater
than 0 and evenly divisible by 8. This at-
tribute can be used only with NEXT-C-SID
flavor.
ioam6
freq K/N - Inject IOAM in K packets every N
packets (default is 1/1).
mode inline - Directly insert IOAM after IPv6
header (default mode).
mode encap - Encapsulate packet in an outer
IPv6 header with IOAM.
mode auto - Automatically use inline mode for
local packets and encap mode for in-transit
packets.
tunsrc ADDRESS - IPv6 address of the tunnel
source (outer header), not used with inline
mode. It is optional: if not provided, the
tunnel source address is chosen automatically.
tundst ADDRESS - IPv6 address of the tunnel
destination (outer header), not used with in-
line mode.
type IOAM6_TRACE_TYPE - List of IOAM data re-
quired in the trace, represented by a bitfield
(24 bits).
ns IOAM6_NAMESPACE - Numerical value to repre-
sent an IOAM namespace. See ip-ioam(8).
size IOAM6_TRACE_SIZE - Size, in octets, of
the pre-allocated trace data block.
xfrm
if_id IF_ID [ link_dev LINK_DEV ]
expires TIME (Linux 4.4+ only)
the route will be deleted after the expires time. Only
support IPv6 at present.
ttl-propagate { enabled | disabled }
Control whether TTL should be propagated from any encap
into the un-encapsulated packet, overriding any global
configuration. Only supported for MPLS at present.
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 pre-
fixes 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 se-
lects 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 table main. 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.
vrf NAME
show the routes for the table associated with the vrf name
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 ta-
ble 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 [ FAMILY ] 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 de-
scribed 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.
fibmatch
Return full fib lookup matched route. Default is to return
the resolved dst entry
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.
mark MARK
the firewall mark (fwmark)
vrf NAME
force the vrf device on which this packet will be routed.
ipproto PROTOCOL
ip protocol as seen by the route lookup
sport NUMBER
source port as seen by the route lookup
dport NUMBER
destination port as seen by the route lookup
connected
if no source address (option from) was given, relookup the
route with the source set to the preferred address re-
ceived from the first lookup. If policy routing is used,
it may be a different route.
flowlabel FLOWLABEL
ipv6 flow label as seen by the route lookup
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 route save
save routing table information to stdout
This command behaves like ip route show except that the output is
raw data suitable for passing to ip route restore.
ip route restore
restore routing table information from stdin
This command expects to read a data stream as returned from ip
route save. It will attempt to restore the routing table infor-
mation exactly as it was at the time of the save, so any transla-
tion of information in the stream (such as device indexes) must
be done first. Any existing routes are left unchanged. Any routes
specified in the data stream that already exist in the table will
be ignored.
NOTES
Starting with Linux kernel version 3.6, there is no routing cache for
IPv4 anymore. Hence ip route show cached will never print any entries on
systems with this or newer kernel versions.
EXAMPLES
ip ro
Show all route entries in the kernel.
ip route add default via 192.168.1.1 dev eth0
Adds a default route (for all addresses) via the local gateway
192.168.1.1 that can be reached on device eth0.
ip route add 10.1.1.0/30 encap mpls 200/300 via 10.1.1.1 dev eth0
Adds an ipv4 route with mpls encapsulation attributes attached to
it.
ip -6 route add 2001:db8:1::/64 encap seg6 mode encap segs
2001:db8:42::1,2001:db8:ffff::2 dev eth0
Adds an IPv6 route with SRv6 encapsulation and two segments at-
tached.
ip -6 route add 2001:db8:1::/64 encap seg6local action End.DT46 vrftable
100 dev vrf100
Adds an IPv6 route with SRv6 decapsulation and forward with lookup
in VRF table.
ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors psp
dev eth0
Adds an IPv6 route with SRv6 End behavior with psp flavor enabled.
ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-
csid dev eth0
Adds an IPv6 route with SRv6 End behavior with next-csid flavor en-
abled.
ip -6 route add 2001:db8:1::/64 encap seg6local action End flavors next-
csid lblen 48 nflen 16 dev eth0
Adds an IPv6 route with SRv6 End behavior with next-csid flavor en-
abled and user-provided Locator-Block and Locator-Node Function
lengths.
ip -6 route add 2001:db8:1::/64 encap ioam6 freq 2/5 mode encap tundst
2001:db8:42::1 trace prealloc type 0x800000 ns 1 size 12 dev eth0
Adds an IPv6 route with an IOAM Pre-allocated Trace encapsulation
(ip6ip6) that only includes the hop limit and the node id, config-
ured for the IOAM namespace 1 and a pre-allocated data block of 12
octets (will be injected in 2 packets every 5 packets).
ip route add 10.1.1.0/30 nhid 10
Adds an ipv4 route using nexthop object with id 10.
SEE ALSO
ip(8)
AUTHOR
Original Manpage by Michail Litvak <mci@owl.openwall.com>
iproute2 13 Dec 2012 IP-ROUTE(8)
Generated by dwww version 1.16 on Tue Dec 16 04:27:47 CET 2025.