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@(#)route.8 6.7 (Berkeley) 05/23/90
Route accepts five commands: add , to add a route, flush , to remove all routes, delete , to delete a specific route, change , to changes aspects of a route (such as its gateway), and monitor , to report any changes to the routing information base, routing lookup misses, or suspected network partionings.
The monitor command has the syntax route [ -n ] monitor
The flush command has the syntax route [ -n ] [ -n ] flush [ family ]
where the address family may be specified by any of the -osi , -xns , or -inet keywords.
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 gateway to which packets should be addressed. Routes to a particular host are distinguished from those to a network by interpreting the Internet address associated with destination . The optional keywords -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 128.0.0.32, 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.
If the route is via an interface rather than via 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, and -osi specify that all subsequent addresses are in the XNS or OSI address families, and the names must be numeric specifications rather than symbolic names.
The optional -netmask qualifier is intended to acheieve the effect of an OSI ESIS redirect with the netmask option. One specifies an additional ensuing address parameter (to be interpreted as a network mask). One can override the implicit network mask generated in the inet case by making sure this option follows the destination parameter.
The optional modifiers -rtt , -rttvar , -sendpipe , -recvpipe , -mtu , -hopcount , -expire , and -ssthresh provide initial values to metrics maintained in the routing entry. 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.
All symbolic names specified for a destination or gateway are looked up first as a host name using gethostbyname (3N). If this lookup fails, getnetbyname (3N) 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, and RTM_CHANGE. As such, only the super-user may modify the routing tables.
If the flush command is specified, route will ``flush'' the routing tables of all gateway entries. One can choose to flush only those routes whose destinations are of a given address family, by specifying an optional keyword describing which address family.
The -n option prevents attempts to print host and network names symbolically when reporting actions. The -v option causes additional details to be printed. The -q option supresses all output.
The specified route is being added to the tables. The values printed are from the routing table entry supplied in the ioctl call. If the gateway address used was not the primary address of the gateway (the first one returned by gethostbyname ), 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 -f flag 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 entry.