| ROUTE(8) | System Manager's Manual | ROUTE(8) |
| route | [-fnqSsv] command [[modifiers] args] |
route can be used to modify nearly any aspect of the routing policy, except packet forwarding, which can be manipulated through the sysctl(8) command.
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 route utility provides several commands:
The monitor command has the syntax
The flush command has the syntax
If the flush command is specified, route will ``flush'' the routing tables of all gateway entries. When the address family is specified by any of the -osi, -xns, -atalk, -inet, -inet6, or -mpls modifiers, only routes having destinations with addresses in the delineated family will be manipulated.
The other commands have the following syntax:
where destination is the destination host or network, and 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 can 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; and -net 128.32.130 is interpreted as 128.32.130.0.
The keyword default can be used as the destination to set up a default route to a smart gateway. If no other routes match, this default route will be used as a last resort.
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.
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 in the form described in link_addr(3), and the names must be numeric specifications rather than symbolic names.
The optional modifiers -mpls and -tag specify that all subsequent addresses are in the MPLS address family. See mpls(4) for examples about setting routes involving MPLS.
The optional -netmask qualifier 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. -prefixlen is also available for similar purpose, in IPv4 and IPv6 case.
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:
-cloning RTF_CLONING - generates a new route on use -nocloning ~RTF_CLONING - stop generating new routes on use -cloned RTF_CLONED - cloned route generated by RTF_CLONING -nocloned ~RTF_CLONED - prevent removal with RTF_CLONING parent -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 -noreject ~RTF_REJECT - clear reject flag -blackhole RTF_BLACKHOLE - silently discard pkts (during updates) -noblackhole ~RTF_BLACKHOLE - clear blackhole flag -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 -proxy RTF_ANNOUNCE - make entry a link level proxy
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.
This shows all routes, without DNS resolution (this is useful if the DNS is not available):route add default 192.168.0.1
To install a static route through 10.200.0.1 to reach the network 192.168.1.0/28, use this:route -n show
route add -net 192.168.1.0 -netmask 255.255.255.240 10.200.0.1
Some uses of the -ifa or -ifp modifiers with the add command will incorrectly fail with a “Network is unreachable” message if there is no default route. See case RTM_ADD in sys/net/rtsock.c:route_output for details.
| August 6, 2006 | NetBSD 6.1 |