ROUTE(8) | System Manager's Manual | ROUTE(8) |
route
—
route |
[-dfLnqSsTtv ] command
[[modifiers] args] |
route
is a utility used to manually manipulate the
network routing tables. Except for setting up the default route, it is
normally not needed, as a system routing table management daemon such as
routed(8), should tend to this
task.
route
can be used to modify nearly any
aspect of the routing policy, except packet forwarding, which can be
manipulated through the
sysctl(8) command.
The route
utility supports a limited
number of general options, but a rich command language, enabling the user to
specify any arbitrary request that could be delivered via the programmatic
interface discussed in
route(4).
-d
-f
flush
). If used in
conjunction with the add
,
change
, delete
or
get
commands, route
removes the routes before performing the command.-L
-n
-q
-S
-s
get
command
except for the actual gateway that will be used. How the gateway is
printed depends on the type of route being looked up.-T
-t
-v
The route
utility provides several
commands:
add
flush
flushall
delete
change
get
show
monitor
The monitor command has the syntax
route
[-n
] monitor
[-c
count]If count is specified,
route
exits after receiving
count routing messages.
The flush command has the syntax
route
[-n
] flush
[family]If the flush
command is specified,
route
will ``flush'' the routing tables of all
gateway entries. When the address family is specified by any of the
-atalk
, -inet
,
-inet6
, or -mpls
modifiers,
only routes having destinations with addresses in the delineated family will
be manipulated.
The other commands have the following syntax:
route
[-n
] command
[-net
|
-host
] destination gatewaywhere destination is the destination host or
network, and gateway is the next-hop intermediary via
which packets should be routed. Routes to a particular host may be
distinguished from those to a network by interpreting the Internet address
specified as the destination argument. The optional
modifiers -net
and -host
force the destination to be interpreted as a network or a host,
respectively. Otherwise, if the destination has a
``local address part'' of INADDR_ANY
, or if the
destination is the symbolic name of a network, then
the route is assumed to be to a network; otherwise, it is presumed to be a
route to a host. Optionally, the destination can also
be specified in the net/bits
format.
For example, 128.32
is interpreted as
-host
128.0.0.32
;
128.32.130
is interpreted as
-host
128.32.0.130
;
-net
128.32
is interpreted
as 128.32.0.0
; and -net
128.32.130
is interpreted as
128.32.130.0
.
The keyword default
can be used as the
destination to set up a default route to a smart
gateway. If no other routes match, this default route
will be used as a last resort.
If the destination is directly reachable via an interface
requiring no intermediary system to act as a gateway, the
-interface
modifier should be specified; the gateway
given is the address of this host on the common network, indicating the
interface to be used for transmission.
The optional modifiers -atalk
, and
-link
specify that all subsequent addresses are in
the AppleTalk address family, or are specified as link-level addresses in
the form described in
link_addr(3), and the names
must be numeric specifications rather than symbolic names.
The optional modifier -tag
specifies an
address associated with the route. How the address is used is specific to
the address family of the destination and the interface used to forward the
packet. Currently route tags are consumed only by the
mpls(4) stack; therefore
route
assumes that the subsequent addresses are in
the MPLS address family. See
mpls(4) for examples of setting
routes involving MPLS.
The optional -netmask
qualifier is
intended to achieve the effect of an ESIS redirect with the netmask option,
or to manually add subnet routes with netmasks different from that of the
implied network interface (as would otherwise be communicated using the OSPF
or ISIS routing protocols). One specifies an additional ensuing address
parameter (to be interpreted as a network mask). The implicit network mask
generated in the AF_INET
case can be overridden by
making sure this option follows the destination parameter.
-prefixlen
is also available for similar purpose, in
IPv4 and IPv6 case.
Routes have associated flags which influence operation of the protocols when sending to destinations matched by the routes. These flags are displayed using the following ID characters in the routing display and may be set (or sometimes cleared) by indicating the following corresponding modifiers:
ID | Modifier | Flag Bit | Description |
|
-iface | ~RTF_GATEWAY | destination is directly reachable |
1 |
-proto1 | RTF_PROTO1 | set protocol specific flag #1 |
2 |
-proto2 | RTF_PROTO2 | set protocol specific flag #2 |
B |
-blackhole | RTF_BLACKHOLE | discard pkts (during updates) |
b |
RTF_BROADCAST | Route represents a broadcast address | |
|
-noblackhole | ~RTF_BLACKHOLE | clear blackhole flag |
C |
-cloning | RTF_CLONING | (deprecated) same as -connected |
|
-nocloning | ~RTF_CLONING | (deprecated) same as -noconnected |
C |
-connected | RTF_CONNECTED | treat as a connected route |
|
-noconnected | ~RTF_CONNECTED | stop treating a connected route |
D |
RTF_DYNAMIC | created dynamically (redirect) | |
G |
RTF_GATEWAY | forwarded to dest by intermediary | |
H |
RTF_HOST | host entry (net otherwise) | |
l |
RTF_LOCAL | Route represents a local address | |
M |
RTF_MODIFIED | modified dynamically (redirect) | |
p |
-proxy | RTF_ANNOUNCE | make entry a link level proxy |
R |
-reject | RTF_REJECT | send ICMP unreachable on match |
|
-noreject | ~RTF_REJECT | clear reject flag |
S |
-static | RTF_STATIC | manually added route |
|
-nostatic | ~RTF_STATIC | pretend route added automatically |
U |
RTF_UP | route usable |
The optional modifiers -rtt
,
-rttvar
, -sendpipe
,
-recvpipe
, -mtu
,
-hopcount
, -expire
, and
-ssthresh
provide initial values to quantities
maintained in the routing entry by transport level protocols, such as TCP or
TP4. These may be individually locked by preceding each such modifier to be
locked by the -lock
meta-modifier, or one can
specify that all ensuing metrics may be locked by the
-lockrest
meta-modifier.
In a change
or add
command where the destination and gateway are not sufficient to specify the
route the -ifp
or -ifa
modifiers may be used to determine the interface or interface address.
All symbolic names specified for a destination or gateway are looked up first as a host name using gethostbyname(3). If this lookup fails, getnetbyname(3) is then used to interpret the name as that of a network.
route
uses a routing socket and the new
message types RTM_ADD
,
RTM_DELETE
, RTM_GET
, and
RTM_CHANGE
. As such, only the super-user may modify
the routing tables.
route
utility exits 0 on success,
and >0 if an error occurs. This includes the use of the
get
command to look up a route that is incomplete.
route add default
192.168.0.1
route -n show
route add -net 192.168.1.0 -netmask
255.255.255.240 10.200.0.1
flush
command is specified, each routing
table entry deleted is indicated with a message of this form.route
command appeared in
4.2BSD. IPv6 support was added by WIDE/KAME project.
Since NetBSD 8.0,
-cloned
, -nocloned
,
-llinfo
and -xresolve
were
obsolete and -cloning
and
-nocloning
were deprecated.
-connected
and -noconnected
appeared in NetBSD 8.0.
Some uses of the -ifa
or
-ifp
modifiers with the add command will incorrectly
fail with a “Network is unreachable” message if there is no
default route. See case RTM_ADD
in
sys/net/rtsock.c:route_output for details.
July 31, 2018 | NetBSD 9.4 |