other versions
- wheezy 20120521-3+b3
- wheezy-backports 3.16.0-2~bpo70+1
- jessie 3.16.0-2
- testing 4.9.0-1
- unstable 4.9.0-1
IP-ROUTE(8) | Linux | IP-ROUTE(8) |
NAME¶
ip-route - routing table managementSYNOPSIS¶
ip [ ip-OPTIONS ] route { COMMAND | help }
DESCRIPTION¶
ip route is used to manipulate entries in the kernel routing tables.unicast - the route entry describes real paths to the destinations covered by the route prefix.
- ip route add
- add new route
- ip route change
- change route
- ip route replace
- change or add new one
- to TYPE PREFIX (default)
- the destination prefix of the route. If TYPE is
omitted, ip assumes type unicast. Other values of
TYPE are listed above. PREFIX is an IP or IPv6 address
optionally followed by a slash and the prefix length. If the length of the
prefix is missing, ip assumes a full-length host route. There is
also a special PREFIX default - which is equivalent to IP
0/0 or to IPv6 ::/0.
- tos TOS
- dsfield TOS
- the Type Of Service (TOS) key. This key has no associated
mask and the longest match is understood as: First, compare the TOS of the
route and of the packet. If they are not equal, then the packet may still
match a route with a zero TOS. TOS is either an 8 bit hexadecimal
number or an identifier from /etc/iproute2/rt_dsfield.
- metric NUMBER
- preference NUMBER
- the preference value of the route. NUMBER is an
arbitrary 32bit number.
- table TABLEID
- the table to add this route to. TABLEID may be a
number or a string from the file /etc/iproute2/rt_tables. If this
parameter is omitted, ip assumes the main table, with the
exception of local, broadcast and nat routes, which
are put into the local table by default.
- dev NAME
- the output device name.
- via ADDRESS
- the address of the nexthop router. Actually, the sense of
this field depends on the route type. For normal unicast routes it
is either the true next hop router or, if it is a direct route installed
in BSD compatibility mode, it can be a local address of the interface. For
NAT routes it is the first address of the block of translated IP
destinations.
- src ADDRESS
- the source address to prefer when sending to the
destinations covered by the route prefix.
- realm REALMID
- the realm to which this route is assigned. REALMID
may be a number or a string from the file /etc/iproute2/rt_realms.
- mtu MTU
- mtu lock MTU
- the MTU along the path to the destination. If the modifier
lock is not used, the MTU may be updated by the kernel due to Path
MTU Discovery. If the modifier lock is used, no path MTU discovery
will be tried, all packets will be sent without the DF bit in IPv4 case or
fragmented to MTU for IPv6.
- window NUMBER
- the maximal window for TCP to advertise to these
destinations, measured in bytes. It limits maximal data bursts that our
TCP peers are allowed to send to us.
- rtt TIME
- the initial RTT ('Round Trip Time') estimate. If no suffix
is specified the units are raw values passed directly to the routing code
to maintain 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
milliseconds.
- rttvar TIME (2.3.15+ only)
- the initial RTT variance estimate. Values are specified as
with rtt above.
- rto_min TIME (2.6.23+ only)
- the minimum TCP Retransmission TimeOut to use when
communicating with this destination. Values are specified as with
rtt above.
- ssthresh NUMBER (2.3.15+ only)
- an estimate for the initial slow start threshold.
- cwnd NUMBER (2.3.15+ only)
- the clamp for congestion window. It is ignored if the
lock flag is not used.
- initcwnd NUMBER (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.
- quickack BOOL (3.11+ only)
- Enable or disable quick ack for connections to this
destination.
- advmss NUMBER (2.3.15+ only)
- the MSS ('Maximal Segment Size') to advertise to these
destinations when establishing TCP connections. If it is not given, Linux
uses a default value calculated from the first hop device MTU. (If the
path to these destination is asymmetric, this guess may be wrong.)
- reordering NUMBER (2.3.15+ only)
- Maximal reordering on the path to this destination. If it
is not given, Linux uses the value selected with sysctl variable
net/ipv4/tcp_reordering.
- nexthop NEXTHOP
- the nexthop of a multipath route. NEXTHOP is a
complex value with its own syntax similar to the top level argument lists:
via ADDRESS - is the nexthop router.
- scope SCOPE_VAL
- the scope of the destinations covered by the route prefix.
SCOPE_VAL may be a number or a string from the file
/etc/iproute2/rt_scopes. If this parameter is omitted, ip
assumes scope global for all gatewayed unicast routes, scope
link for direct unicast and broadcast routes and
scope host for local routes.
- protocol RTPROTO
- the routing protocol identifier of this route.
RTPROTO may be a number or a string from the file
/etc/iproute2/rt_protos. If the routing protocol ID is not given,
ip assumes protocol boot (i.e. it assumes the route was
added by someone who doesn't understand what they are doing). Several
protocol values have a fixed interpretation. Namely:
redirect - the route was installed due to an ICMP redirect.
- 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 table main. TABLEID may either be the ID of a real
table or one of the special values:
all - list all of the tables.
- cloned
- cached
- list cloned routes i.e. routes which were dynamically
forked from other routes because some route attribute (f.e. MTU) was
updated. Actually, it is equivalent to table cache.
- from SELECTOR
- the same syntax as for to, but it binds the source
address range rather than destinations. Note that the from option
only works with cloned routes.
- protocol RTPROTO
- only list routes of this protocol.
- scope SCOPE_VAL
- only list routes with this scope.
- type TYPE
- only list routes of this type.
- dev NAME
- only list routes going via this device.
- via PREFIX
- only list routes going via the nexthop routers selected by
PREFIX.
- src PREFIX
- only list routes with preferred source addresses selected
by PREFIX.
- realm REALMID
- realms FROMREALM/TOREALM
- only list routes with these realms.
- ip route flush
- flush routing tables
this command flushes routes selected by some
criteria.
The arguments have the same syntax and semantics as the arguments of ip route
show, but routing tables are not listed but purged. The only difference is
the default action: show dumps all the IP main routing table but
flush prints the helper page.
With the -statistics option, the command becomes verbose. It prints out
the number of deleted routes and the number of rounds made to flush the
routing table. If the option is given twice, ip route flush also dumps
all the deleted routes in the format described in the previous
subsection.
- ip route get
- get a single route
this command gets a single route to a
destination and prints its contents exactly as the kernel sees it.
- to ADDRESS (default)
- the destination address.
- from ADDRESS
- the source address.
- tos TOS
- dsfield TOS
- the Type Of Service.
- iif NAME
- the device from which this packet is expected to arrive.
- oif NAME
- force the output device on which this packet will be
routed.
- connected
- if no source address (option from) was given,
relookup the route with the source set to the preferred address received
from the first lookup. If policy routing is used, it may be a different
route.
- 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 information exactly as it was at the time of the save, so any
translation 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.
EXAMPLES¶
ip roShow 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.
SEE ALSO¶
ip(8)AUTHOR¶
Original Manpage by Michail Litvak <mci@owl.openwall.com>13 Dec 2012 | iproute2 |