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

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
ROUTE(8)                FreeBSD System Manager's Manual               ROUTE(8)

     route - manually manipulate the routing tables

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

     Route is a utility 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:

     -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 forgot this, especially when attempting to repair
             networking operations).

     -v      (verbose) Print additional details.

     -q      Suppress all output.

     The route utility provides six commands:

     add         Add a route.
     flush       Remove all routes.
     delete      Delete a specific route.
     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

     The monitor command has the syntax:

           route [-n] monitor

     The flush command has the syntax:

           route [-n] flush [family]

     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, -atalk, or -inet modifiers, only routes having
     destinations with addresses in the delineated family will be deleted.

     The other commands have the following syntax:

           route [-n] command [-net | -host] destination gateway

     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.

     For example, 128.32 is interpreted as -host; 128.32.130 is
     interpreted as -host; -net 128.32 is interpreted as; and -net 128.32.130 is interpreted as

     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, -atalk, and -link specify that all
     subsequent addresses are in the XNS, OSI, or AppleTalk 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.

     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

     -cloning   RTF_CLONING    - generates a new route on use
     -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
     -llinfo    RTF_LLINFO     - validly translates proto addr to link addr

     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.

     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.

     Route 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.

     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 wasn't
             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

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

     The route command appeared in 4.2BSD.

     The first paragraph may have slightly exaggerated routed(8)'s abilities.

BSD 4.4                         March 19, 1994                         BSD 4.4


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

home | help