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 route(4).

The following options are available:

The route utility provides the following commands:

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, -inet6, 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 [netmask]

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 -net 0.0.0.0, which is the default route.

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.

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 modifiers:

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.

The optional -proxy modifier specifies that the RTF_LLINFO routing table entry is the ``published (proxy-only)'' ARP entry, as reported by arp(8).

The optional -genmask modifier specifies that a cloning mask is present. This specifies the mask applied when determining if a child route should be created. It is only applicable to network routes with the RTF_CLONING flag set.

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_CHANG.

Exit Status

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

Diagnostics

Requirements