Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
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 ta-
     bles.  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 inet6 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 ex-
	     pedient to	forget this, especially	when attempting	to repair net-
	     working 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 com-

     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 partition-
     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 ta-
     bles 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	modi-
     fiers.  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

     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 inter-
     preting 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 net-
     work; 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 in-
     terpreted 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.  Alter-
     nately, if	the interface is point to point	the name of the	interface it-
     self may be given,	in which case the route	remains	valid even if the lo-
     cal 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	proto-
     cols).  One specifies an additional ensuing address parameter (to be in-
     terpreted 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 ex-
     ample, -prefixlen 32 specifies that a network mask	of
     ffff:ffff:0000:0000:0000:0000:0000:0000 will be used.  The	default	pre-
     fixlen 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

     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 mod-

     -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 en-
     suing 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	cur-
     rent time.

     The optional modifier -fib	number specifies that the command will be ap-
     plied 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 suf-
     ficient 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 de-
     termine 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	de-
     fault 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 gate-

	   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 be-
     ing 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 gate-
     way 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	gate-
     way 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	13.0			January	9, 2019			  FreeBSD 13.0


Want to link to this manual page? Use this URL:

home | help