ROUTE(8) Maintenance Commands and Procedures ROUTE(8)

NAME

route - manually manipulate the routing tables

SYNOPSIS

route [-fnvq] [-z zone] sub-command [ [modifiers] args]


route [-fnvq] [-z zone] [-p [-R root-dir]] add | delete [modifiers] destination gateway
[args]


route [-fnvq] [-z zone] change | get [modifiers] destination
[gateway [args]]


route [-fn] [-z zone] monitor [modifiers]


route [-fnvq] [-z zone] flush [modifiers]


route -p [-R root-dir] [-z zone] show

DESCRIPTION

route manually manipulates the network routing tables. These tables are
normally maintained by the system routing daemon, such as in.routed(8)
and in.ripngd(8).


route supports a limited number of general options, but a rich command
language. Users can specify an arbitrary request that can be delivered by
means of the programmatic interface discussed in route(4P).


route uses a routing socket and the new message types RTM_ADD,
RTM_DELETE, RTM_GET, and RTM_CHANGE. While only superusers can modify
routing tables, the RTM_GET operation is allowed for non-privileged
users.

OPTIONS

-f
Flush the routing tables of all gateway entries. If you
use the -f option in conjunction with any of the route
subcommands, route flushes the gateways before performing
the subcommand. Specify the table to flush by placing the
inet or inet6 modifier immediately after the -f option. If
unspecified, flushing IPv4 (inet) routes is the default.


-n
Prevent attempts to print host and network names
symbolically when reporting actions. This option is useful
when name servers are unavailable.


-p
Make changes to the network route tables persistent across
system restarts. The operation is applied to the network
routing tables first and, if successful, is then applied
to the list of saved routes used at system startup. In
determining whether an operation was successful, a failure
to add a route that already exists or to delete a route
that is not in the routing table is ignored. At startup,
any directly reachable routes (those specified with the
-interface or -iface options) will be created first,
followed by any remaining routes. Particular care should
be taken when using host or network names in persistent
routes, as network-based name resolution services are not
available at the time routes are added at startup.


-q
Suppress all output.


-R root-dir
Specify an alternate root directory where route applies
changes. This option is ignored unless used in conjunction
with the -p option. When -R is specified, route changes
are applied only to the list of saved routes to be used at
startup, not to the network routing tables. In addition,
certain checks, such as the existence of network
interfaces used with -ifp, are skipped.


-v
Print additional details in verbose mode.


-z zone
Apply commands to the zone zone. The zone must be running
and must not be a shared-IP zone.

Subcommands

The following subcommands are supported:

add
Add a route.


change
Change aspects of a route (such as its gateway).


delete
Delete a specific route.


flush
Remove all gateway entries from the routing table.


get
Look up and display the route for a destination.


monitor
Continuously report any changes to the routing information
base, routing lookup misses, or suspected network
partitionings.


show
Display the list of routes to be applied at system startup.
Can be used only in conjunction with the -p option.


The add and delete subcommands have the following syntax:

route [ -fnvq ] cmd destination gateway [metric/netmask]


where cmd is add or delete, destination is the destination host or
network, and gateway is the next-hop intermediary through which packets
should be routed. Modifiers described in OPERANDS can be placed anywhere
on the command line.


The get and change subcommands have the following syntax:

route [ -fnvq ] cmd destination [gateway [metric/netmask]]


where cmd is get or change, destination is the destination host or
network, and gateway is the next-hop intermediary through which packets
should be routed. Modifiers described in OPERANDS can be placed anywhere
on the command line.


The monitor subcommand has the following syntax:

route monitor [ -inet | -inet6 ]

OPERANDS

route executes its subcommands on routes to destinations by way of
gateways.

Destinations and Gateways

By default, destination and gateway addresses are interpreted as IPv4
addresses. All symbolic names are tried first as a host name, using
getipnodebyname(3SOCKET). If this lookup fails in the AF_INET case,
getnetbyname(3SOCKET) interprets the name as that of a network.


Including an optional modifier on the command line before the address
changes how the route subcommand interprets it.


The following modifiers are supported:

-inet
Force the address to be interpreted as an IPv4 address, that
is, under the AF_INET address family.


-inet6
Force the address to be interpreted as an IPv6 address, that
is, under the AF_INET6 address family.


For IPv4 addresses, routes to a particular host are by default
distinguished from those to a network by interpreting the Internet
address specified as the destination. If the destination has a local
address part (that is, the portion not covered by the netmask) of 0, or
if the destination is resolved as 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.


You can force this selection by using one of the following modifiers:

-host
Force the destination to be interpreted as a host.


-net
Force the destination to be interpreted as a network.


For example:


Destination Destination Equivalent
-----------------------------------------
128.32 -host 128.0.0.32
128.32.130 -host 128.32.0.130
-net 128.32 128.32.0.0
-net 128.32.130 128.32.130.0


Two modifiers avoid confusion between addresses and keywords (for
example, host used as a symbolic host name). You can distinguish a
destination by preceding it with the -dst modifier. You can distinguish a
gateway address by using the -gateway modifier. If the destination is
directly reachable by way of an interface requiring no intermediary IP
router to act as a gateway, this can be indicated by using the -interface
or -iface modifier.


In the following example, the route does not refer to an external gateway
(router), but rather to one of the machine's interfaces. Packets with IP
destination addresses matching the destination and mask on such a route
are sent out on the interface identified by the gateway address. For
interfaces using the ARP protocol, this type of route is used to specify
that all matching destinations are local to the physical link. That is, a
host could be configured to ARP for all addresses, without regard to the
configured interface netmask, by adding a default route using this
command. For example:

example# route add default hostname -interface


where gateway address hostname is the name or IP address associated with
the network interface over which all matching packets should be sent. On
a host with a single network interface, hostname is usually the same as
the nodename returned by the uname -n command. See uname(1).


For backward compatibility with older systems, directly reachable routes
can also be specified by placing a 0 after the gateway address:

example# route add default hostname 0


This value was once a route metric, but this metric is no longer used. If
the value is specified as 0, then the destination is directly reachable
(equivalent to specifying -interface). If it is non-zero but cannot be
interpreted as a subnet mask, then a gateway is used (default).


With the AF_INET address family or an IPv4 address, a separate subnet
mask can be specified. This can be specified in one of the following
ways:

o IP address following the gateway address . This is typically
specified in decimal dot notation as for inet_addr(3C) rather
than in symbolic form.

o IP address following the -netmask qualifier.

o Slash character and a decimal length appended to the
destination address.


If a subnet mask is not specified, the mask used is the subnet mask of
the output interface selected by the gateway address, if the classful
network of the destination is the same as the classful network of the
interface. Otherwise, the classful network mask for the destination
address is used.


Each of the following examples creates an IPv4 route to the destination
192.0.2.32 subnet with a subnet mask of 255.255.255.224:

example# route add 192.0.2.32/27 somegateway
example# route add 192.0.2.32 -netmask 255.255.255.224 somegateway
example# route add 192.0.2.32 somegateway 255.255.255.224


For IPv6, only the slash format is accepted. The following example
creates an IPv6 route to the destination 33fe:: with a netmask of 16 one-
bits followed by 112 zero-bits.

example# route add -inet6 3ffe::/16 somegateway


In cases where the gateway does not uniquely identify the output
interface (for example, when several interfaces have the same address),
you can use the -ifp ifname modifier to specify the interface by name.
For example, -ifp lo0 associates the route with the lo0 interface. If the
named interface is an underlying interface in an IPMP (IP multipathing)
group, then requests to add a route will automatically be translated to
the corresponding IPMP IP interface, and requests to delete or change a
route on an underlying interface will fail.

Routing Flags

Routes have associated flags that influence operation of the protocols
when sending to destinations matched by the routes. These flags can be
set (and in some cases cleared, indicated by ~) by including the
following modifiers on the command line:


Modifier Flag Description
---------------------------------------------------------------------
-interface ~RTF_GATEWAY Destination is directly reachable
-iface ~RTF_GATEWAY Alias for interface modifier
-static RTF_STATIC Manually added route
-nostatic ~RTF_STATIC Pretend route was added by kernel or
routing daemon
-reject RTF_REJECT Emit an ICMP unreachable when matched
-blackhole RTF_BLACKHOLE Silently discard packets during updates
-proto1 RTF_PROTO1 Set protocol specific routing flag #1
-proto2 RTF_PROTO2 Set protocol specific routing flag #2
-private RTF_PRIVATE Do not advertise this route
-multirt RTF_MULTIRT Creates the specified redundant route
-setsrc RTF_SETSRC Assigns the default source address


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. These can be individually locked either by preceding each modifier
to be locked by the -lock meta-modifier, or by specifying that all
ensuing metrics can be locked by the -lockrest meta-modifier.


Some transport layer protocols can support only some of these metrics.
The following optional modifiers are supported:

-expire
Lifetime for the entry. This optional modifier is not
currently supported.


-hopcount
Maximum hop count. This optional modifier is not currently
supported.


-mtu
Maximum MTU in bytes.


-recvpipe
Receive pipe size in bytes.


-rtt
Round trip time in microseconds.


-rttvar
Round trip time variance in microseconds.


-sendpipe
Send pipe size in bytes.


-ssthresh
Send pipe size threshold in bytes.


-secattr
Security attributes of the route. This modifier is available
only if the system is configured with the Solaris Trusted
Extensions feature.

The -secattr modifier has the following format:

min_sl=val,max_sl=val,doi=val,cipso

or:

sl=VAL,doi=VAL,cipso

In the first form, above, the val for min_sl and max_sl is a
sensitivity label in either hex or string form. The val for
doi is a non-negative integer. The route will apply only for
packets with the same domain of interpretation as defined by
the doi value and within the accreditation range defined by
the min_sl and max_sl values. The cipso keyword is optional
and set by default. Valid min_sl, max_sl and doi
keyword/value pairs are mandatory. Note that if val contains
a space, it must be protected by double quotes.

The second form, above, is equivalent to specifying the
first form with the same VAL for min_sl and max_sl. The
second form should be used for the get command, because get
uses only a single sensitivity label.

Compatibility

The modifiers host and net are taken to be equivalent to -host and -net.
To specify a symbolic address that matches one of these names, use the
dst or gateway keyword to distinguish it. For example: -dst host


The following two flags are also accepted for compatibility with older
systems, but have no effect.


Modifier Flag
-------------------------
-cloning RTF_CLONING
-xresolve RTF_XRESOLVE


The -ifa hostname modifier is also accepted, but has no effect.

FILES

/etc/defaultrouter
List of default routers


/etc/hosts
List of host names and net addresses


/etc/networks
List of network names and addresses

SEE ALSO

uname(1), ioctl(2), inet_addr(3C), getipnodebyname(3SOCKET),
getnetbyname(3SOCKET), ARP(4P), ip(4P), route(4P), routing(4P),
defaultrouter(5), hosts(5), networks(5), attributes(7), in.ripngd(8),
in.routed(8), netstat(8), routed(8)

DIAGNOSTICS

add [ host| network] destination:gateway flags

The specified route is being added to the tables. The values printed
are from the routing table entry supplied in the ioctl(2) call. If
the gateway address used was not the primary address of the gateway
(the first one returned by getipnodebyname(3SOCKET)) the gateway
address is printed numerically as well as symbolically.


delete [ host| network] destination:gateway flags
change [ host| network] destination:gateway flags

As add, but when deleting or changing an entry.


destination done

When the -f flag is specified, or the flush subcommand is used, each
routing table entry deleted is indicated with a message of this form.


Network is unreachable

An attempt to add a route failed because the gateway listed was not
on a directly-connected network. Give the next-hop gateway instead.


not in table

A delete operation was attempted for an entry that is not in the
table.


entry exists

An add operation was attempted for a route that already exists in the
kernel.


routing table overflow

An operation was attempted, but the system was unable to allocate
memory to create the new entry.


insufficient privileges

An attempt to add, delete, change, or flush a route failed because
the calling process does not have appropriate privileges.

NOTES

Specifying that destinations are local (with the -interface modifier)
assumes that the routers implement proxy ARP, meaning that they respond
to ARP queries for all reachable destinations. Normally, using either
router discovery or RIP is more reliable and scalable than using proxy
ARP. See in.routed(8) for information related to RIP.


Combining the all destinations are local route with subnet or network
routes can lead to unpredictable results. The search order as it relates
to the all destinations are local route are undefined and can vary from
release to release.

August 29, 2021 ROUTE(8)