Command Section
ROUTE(8)                FreeBSD System Manager's Manual               ROUTE(8)

     route - manually manipulate the routing tables

     route [-dnqtv] command [[modifiers] args]

     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

     The following options are available:

     -4      Specify inet address family as family hint for subcommands.

     -6      Specify inet address family as family hint for subcommands.

     -d      Run in debug-only mode, i.e., do not actually modify the routing

     -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

     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
     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 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 (, 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; 128.32.130 is
     interpreted as -host; -net 128.32 is interpreted as; -net 128.32.130 is interpreted as; and
     192.168.64/20 is interpreted as -net 192.168.64 -netmask

     A destination of default is a synonym for the default route.  For IPv4 it
     is -net -inet, 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 network mask of
     ffff:ffff:0000:0000:0000:0000:0000:0000 to be used.  The default value of
     prefixlen is 64 to get along with the aggregatable address.  But 0 is
     assumed if default is specified.  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

     -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.

     The route utility exits 0 on success, and >0 if an error occurs.

     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

           route add -net

     A shorter version of adding a default route can also be written as:

           route add default

     Add a static route to the network via the

           route add -net

     Change the gateway of an already established static route in the routing

           route change -net

     Display the route for a destination network:

           route show

     Delete a static route from the routing table:

           route delete -net

     Remove all routes from the routing table:

           route flush

     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

     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

     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.

     netintro(4), route(4), arp(8), routed(8)

     The route utility appeared in 4.2BSD.

     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 11.1-RELEASE-p4        November 11, 2014       FreeBSD 11.1-RELEASE-p4
Command Section