ROUTE(8) FreeBSD System Manager's Manual ROUTE(8)
NAME
route - manually manipulate the routing tables
SYNOPSIS
route [-dnqtv] command [[modifiers] args]
DESCRIPTION
The route utility is used to manually manipulate the network routing
tables. It normally is not needed, as a system routing table management
daemon, such as routed(8), should tend to this task.
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).
The following options are available:
-4 Specify inet address family as family hint for subcommands.
-6 Specify inet6 address family as family hint for subcommands.
-d Run in debug-only mode, i.e., do not actually modify the routing
table.
-n Bypass attempts to print host and network names symbolically when
reporting actions. (The process of translating between symbolic
names and numerical equivalents can be quite time consuming, and
may require correct operation of the network; thus it may be
expedient to forget this, especially when attempting to repair
networking operations).
-t Run in test-only mode. /dev/null is used instead of a socket.
-v (verbose) Print additional details.
-q Suppress all output from the add, change, delete, and flush
commands.
The route utility provides the following commands:
add Add a route.
flush Remove all routes.
delete Delete a specific route.
del Another name for the delete command.
change Change aspects of a route (such as its gateway).
get Lookup 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 Another name for the get command.
The monitor command has the syntax:
route [-n] monitor [-fib number]
The flush command has the syntax:
route [-n] flush [family] [-fib number]
If the flush command is specified, route will ``flush'' the routing
tables of all gateway entries. When the address family may is specified
by any of the -osi, -xns, -inet6, or -inet modifiers, only routes having
destinations with addresses in the delineated family will be deleted.
Additionally, -4 or -6 can be used as aliases for -inet and -inet6
modifiers. When a -fib option is specified, the operation will be
applied to the specified FIB (routing table).
The add command has the following syntax:
route [-n] add [-net | -host] destination gateway [netmask] [-fib
number]
and the other commands have the following syntax:
route [-n] command [-net | -host] destination [gateway [netmask]]
[-fib number]
where destination is the destination host or network, 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 (0.0.0.0), 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 could 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; -net 128.32.130 is interpreted as 128.32.130.0; and
192.168.64/20 is interpreted as -net 192.168.64 -netmask 255.255.240.0.
A destination of default is a synonym for the default route. For IPv4 it
is -net -inet 0.0.0.0, and for IPv6 it is -net -inet6 ::.
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.
Alternately, if the interface is point to point the name of the interface
itself may be given, in which case the route remains valid even if the
local or remote addresses change.
The optional modifiers -xns, -osi, and -link specify that all subsequent
addresses are in the XNS or OSI address families, or are specified as
link-level addresses, and the names must be numeric specifications rather
than symbolic names.
The optional -netmask modifier is intended to achieve the effect of an
OSI 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.
For AF_INET6, the -prefixlen qualifier is available instead of the -mask
qualifier because non-continuous masks are not allowed in IPv6. For
example, -prefixlen 32 specifies that a network mask of
ffff:ffff:0000:0000:0000:0000:0000:0000 will be used. The default
prefixlen is 64. However, it is assumed to be 0 if default is specified
for destination. Note that the qualifier works only for AF_INET6 address
family.
Routes have associated flags which influence operation of the protocols
when sending to destinations matched by the routes. These flags may be
set (or sometimes cleared) by indicating the following corresponding
modifiers:
-xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
-iface ~RTF_GATEWAY - destination is directly reachable
-static RTF_STATIC - manually added route
-nostatic ~RTF_STATIC - pretend route added by kernel or daemon
-reject RTF_REJECT - emit an ICMP unreachable when matched
-blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
-proto1 RTF_PROTO1 - set protocol specific routing flag #1
-proto2 RTF_PROTO2 - set protocol specific routing flag #2
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.
Note that -expire accepts expiration time of the route as the number of
seconds since the Epoch (see time(3)). When the first character of the
number is "+" or "-", it is interpreted as a value relative to the
current time.
The optional modifier -fib number specifies that the command will be
applied to a non-default FIB. The number must be smaller than the
net.fibs sysctl(8) MIB. When this modifier is not specified, or a
negative number is specified, the default FIB shown in the net.my_fibnum
sysctl(8) MIB will be used.
The number allows multiple FIBs by a comma-separeted list and/or range
specification. The "-fib 2,4,6" means the FIB number 2, 4, and 6. The
"-fib 1,3-5,6" means the 1, 3, 4, 5, and 6.
In a change or add command where the destination and gateway are not
sufficient to specify the route (as in the ISO case where several
interfaces may have the same address), 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.
The route utility 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.
EXIT STATUS
The route utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
Add a default route to the network routing table. This will send all
packets for destinations not available in the routing table to the
default gateway at 192.168.1.1:
route add -net 0.0.0.0/0 192.168.1.1
A shorter version of adding a default route can also be written as:
route add default 192.168.1.1
Add a static route to the 172.16.10.0/24 network via the 172.16.1.1
gateway:
route add -net 172.16.10.0/24 172.16.1.1
Change the gateway of an already established static route in the routing
table:
route change -net 172.16.10.0/24 172.16.1.2
Display the route for a destination network:
route show 172.16.10.0
Delete a static route from the routing table:
route delete -net 172.16.10.0/24 172.16.1.2
Remove all routes from the routing table:
route flush
DIAGNOSTICS
add [host | network ] %s: gateway %s flags %x 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
gethostbyname(3)), the gateway address is printed numerically as well as
symbolically.
delete [ host | network ] %s: gateway %s flags %x As above, but when
deleting an entry.
%s %s done When the flush command is specified, 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. The next-hop
gateway must be given.
not in table A delete operation was attempted for an entry which was not
present in the tables.
routing table overflow An add operation was attempted, but the system
was low on resources and was unable to allocate memory to create the new
entry.
gateway uses the same route A change operation resulted in a route whose
gateway uses the same route as the one being changed. The next-hop
gateway should be reachable through a different route.
SEE ALSO
netintro(4), route(4), arp(8), routed(8)
HISTORY
The route utility appeared in 4.2BSD.
BUGS
The first paragraph may have slightly exaggerated routed(8)'s abilities.
Currently, routes with the RTF_BLACKHOLE flag set need to have the
gateway set to an instance of the lo(4) driver, using the -iface option,
for the flag to have any effect; unless IP fast forwarding is enabled, in
which case the meaning of the flag will always be honored.
FreeBSD 13.1-RELEASE-p6 January 9, 2019 FreeBSD 13.1-RELEASE-p6
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