route - Manipulates the routing tables manually
Adding a Route
route [-nqvC] add [-net | -host] [family] destination[/bitmask]
gateway [-link] [modifiers[args]]
Changing a Route [Toc] [Back]
route [-nqv] change [-net | -host] [family] destination
gateway [-link] [modifiers[args]]
Monitoring a Route [Toc] [Back]
route [-n] monitor
Deleting a Route [Toc] [Back]
route [-nqvC] delete [-net | -host] [family] destination[/bitmask]
[-link] gateway [modifiers[args]]
Deleting All Routes [Toc] [Back]
route [-nqvC] flush [family]
Prints host and network names in numeric format, instead
of symbolic format, when reporting actions. Suppresses
all output. Causes additional details to be printed.
Forces route to use the old ioctl calls instead of the
current route server request path.
Specifies explicitly that this route is a network route;
destination is interpreted as a network address. Specifies
explicitly that this route is a host route; destination
is interpreted as a host address. Specifies the destination
host or network (with or without the optional
Classless Inter-Domain Routing (CIDR) mask (/bitmask)).
Specifies the optional address family of the destination
and gateway parameters. Possible values are: -inet (the
default) and -inet6. If the -link parameter is not specified,
this also specifies the address family of the gateway
parameter. Specifies that the gateway is a link layer
address. If the -link parameter is not specified, the
address family of the gateway parameter is the same as the
destination. Specifies the next hop and gateway to which
packets should be addressed.
The route command is a program used to manually manipulate
the network routing tables. It normally is not needed, as
a system routing table management daemon, such as gated or
routed, should tend to this task.
The route command accepts five commands: Adds a route.
Removes all gateway entries from the routing tables. For
the inet6 family, it also removes all cloned routes. You
can choose to flush only those routes whose destinations
are of a given address family by specifying an optional
keyword (family) that specifies the address family.
Deletes a specific route. Changes aspects of a route
(such as its gateway). Reports any changes to the routing
information base, routing lookup misses, or suspected network
partionings.
Unless the -net or -host parameters are specified on the
command line, route creates a host route or a network
route by interpreting the Internet address associated with
destination parameter. If the destination has a local
address part of INADDR_ANY, or if the destination is the
symbolic name of a network, a network route is created;
otherwise, a host route is created.
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.
All symbolic names specified for a destination or gateway
are looked up first as a hostname using gethostbyname(3).
If this lookup fails, getnetbyname(3) is then used to
interpret the name as that of a network.
Routes added with the route command are marked as
RTF_STATIC to differentiate them from routes added by the
routing daemons (gated or routed). The gated daemon does
not remove the RTF_STATIC routes when it is shut down.
The route command uses a routing socket and the new message
types RTM_ADD, RTM_DELETE, and RTM_CHANGE.
Modifiers [Toc] [Back]
Modifiers provide initial values to metrics and other
information maintained in the routing entry. All modifiers
and their arguments are optional and must appear
after the gateway field on the command line. The modifiers
for the add, change, and delete commands are as follows:
Specifies that the kernel add or delete the specified
route on all interfaces (for example, tu0 and tu1)
that are in the same subnet as the gateway. Use this modifier
only with the add and delete modifiers. Do not use
-all with the -dev and -olddev modifiers. Specifies that
this route is a blackhole route. Packets sent to blackhole
routes are dropped, and no notification is sent to
the packet originators. This is different from a normal
route, which allows packets to be forwarded out on it.
You must specify 127.0.0.1 (localhost) as the gateway
argument. Generates a new route on use of this route.
Specifies the interface device (for example, tu0 and fta0)
to use in the routing entry. Use this modifier when you
want to designate a particular interface for a route. If
you do not specify this modifier, the route is added on
the first interface that is found. Specifies that the
netmask mask is used for all routes cloned from this
route. Sets this route's maximum hopcount to count.
Specifies that this route is via an interface instead of
via a gateway (gateway is the default). This means the
destination is reachable directly via an interface; no
intermediate system is required. The gateway parameter is
the address of this host on the common network, indicating
the interface to be used for transmission. Sets this
route's type as AF_INET. When used with the delete or
flush commands, only AF_INET routes are deleted. Sets
this route's type as AF_INET6. When used with the delete
or flush commands, only AF_INET6 routes are deleted. Sets
this route's type as AF_ISO. When used with the delete or
flush commands, only AF_ISO routes are deleted. Sets this
route's maximum speed, in bits per 200 milliseconds, for
TCP traffic. You can limit bandwidth for either host or
network routes. Sets this route's type as AF_LINK. When
used with the delete or flush commands, only AF_LINK
routes are deleted. Specifies that this route contains
valid link-layer information. Locks the metric set by
next modifier specified on the command line in the routing
entry. A locked metric is not modified by the kernel.
The following metrics can be locked: mtu, hopcount,
recvpipe, sendpipe, ssthresh, rtt, and rttvar. Locks the
metrics set by all modifiers that follow on the command
line in the routing entry. A locked metric is not modified
by the kernel. The following metrics can be locked:
mtu, hopcount, recvpipe, sendpipe, ssthresh, rtt, and
rttvar. Sets this route's maximum transmission unit
(MTU), in bytes, to size. Specifies the subnet mask to
use for the routing entry. Networks that use a nonstandard
subnet must include this modifier. Specify this modifier
after any optional modifiers. Do not specify this
modifier if you specify a CIDR bitmask (/bitmask). Do not
specify this modifier with the change command. Specifies
the old interface device (for example, tu0 and fta0) in
the routing entry that you want to change. Use this modifier
with the change command only to move a route from one
interface to another. See the "Examples" section. Specifies
the old gateway in the routing entry that you want to
change. Use this modifier with the change command only.
See the "Examples" section. Specifies the old interface
in the routing entry that you want to change. Use this
modifier with the change command only. Sets this route's
type as AF_ISO. When used with the delete or flush commands,
only AF_ISO routes are deleted. Specifies that
this route is permanent; it cannot be modified by ICMP
redirects. Sets the precedence of the route to value.
Among equivalent routes to the same destination, the route
with the lower precedence is preferred. Sets this route's
inbound delay bandwidth product (in bytes) to bandwidth.
Specifies that this route is a reject route. Packets sent
to reject routes are dropped and messages designating the
route as unreachable are sent to the packet originators.
This is different from a normal route, which allows packets
to be forwarded out on it. You must specify 127.0.0.1
(localhost) as the gateway argument. Sets this route's
round trip time (in microseconds) to time. Sets this
route's round trip time variance (in microseconds) to
variance. Sets this route's outbound delay bandwidth
product (in bytes) to bandwidth. Sets this route's outbound
gateway buffer limit (in bytes) to threshold.
You must be superuser in order to run the route command
and to modify the routing tables.
The specified route is being added to the tables. If the
gateway address used was not the primary address of the
gateway (the first one returned by gethostbyname), the
gateway address is printed numerically as well as symbolically.
The optional /bitmask parameter was specified with
the change command. Do not specify a bit mask with the
change command. The specified route is being modified in
the tables. The specified route is being deleted from the
tables. If the gateway address used was not the primary
address of the gateway (the first one returned by
gethostbyname), the gateway address is printed numerically
as well as symbolically. When you use the flush command,
each routing table entry deleted is indicated with a message
of this form. An add operation was attempted for an
entry that already exists in the routing tables. The
gateway value is incorrect for creating reject and blackhole
routes. The bitmask specified is not in the range of
1 to 32, inclusive. The -netmask modifier was specified
together with a CIDR bit mask. The optional -netmask modifier
was specified with the change command. Do not specify
a network mask with the change command. An attempt to
add a route failed because the gateway listed was not on a
directly connected network. The next hop gateway must be
given. A delete operation was attempted for an entry that
was not present in the tables. An add operation was
attempted, but the system was low on resources and was
unable to allocate memory to create the new entry.
To add gateway 128.32.0.130 as a default gateway, enter:
route add default 128.32.0.130 To add a route to
host milan via gateway 128.32.0.130, enter: route add
-host milan 128.32.0.130 To delete an existing route
via gateway 128.32.0.130 to host milan, enter: route
delete -host milan 128.32.0.130 To add a route with
a precedence value of 1 to host milan via gateway
128.32.0.130, enter: route add -precedence 1 -host
milan 128.32.0.130 To change an existing route for host
milan via gateway 128.32.0.130 to use a new gateway
128.32.10.101, enter: route change -oldgateway
128.32.0.130 -oldinterface le0 \ -host milan 128.32.10.101
To add a route to network 212.232.32 via gateway
128.32.0.130, enter: route add -net 212.232.32/22
128.32.0.130
The previous example aggregates routes for four
Class C networks: 212.232.32, 212.232.33,
212.232.34, and 212.232.35. To add an IPv6 route
to network feco:10:50::/48 through the configured
tunnel interface ipt0, enter: route add -inet6
fec0:10:50::48 -inet6 fe80::a0a:2805 -dev ipt0 To
add a route to network 212.232.32/22 via gateway
128.32.0.130 and lock the MTU size at 1500, enter:
route add -net 197.45.63/24 214.89.32.235 -lock
-mtu 1500 To add a route to network 212.232.32/22
via gateway 128.32.0.130 and lock the MTU size and
hop count, enter: route add -net 197.45.63/24
214.89.32.235 -lockrest -mtu 1500 \ -hopcount 2 To
change existing network route 206.98.17 via gateway
206.98.17.45 from using interface device tu0 to
tu1, enter: route change -net 206.98.17
206.98.17.45 -olddev tu0 -dev tu1
This assumes that interface device tu1 is configured
with an IP address in the same subnet as tu0.
To change existing network route 206.98.17 from
using gateway 206.98.17.45 to 206.98.17.162, enter:
route change -net 206.98.17 206.98.17.162 -oldgateway
206.98.17.45 To change existing network route
206.98.17 using interface device tu0 and gateway
206.98.17.45 to use device tu1 and gateway
206.98.17.162, enter: route change -net 206.98.17
206.98.17.162 -olddev tu0 -dev tu1 \ -oldgateway
206.98.17.45 To add a route to host 219.67.129.16
via gateway 219.67.122.41 using interface device
tu1, enter: route add -host 219.67.129.16
219.67.122.41 -dev tu1 To delete a route to network
219.84.6 via gateway 219.84.6.79 using interface
device fta0, enter: route delete -net 219.84.6
219.84.6.79 -olddev fta0 To add a route to host
202.54.164.79 via gateway 202.54.163.11 using all
interfaces connected to the 202.54.163/24 subnet,
enter: route add -host 202.54.164.79 202.54.163.11
-all
Specifies the command path
Commands: netstat(1), gated(8), routed(8)
Networking: netintro(7)
route(8)
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