.\" Copyright (c) 1983 The Regents of the University of California.
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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.\" @(#)route.8 6.3 (Berkeley) %G%
route \- manually manipulate the routing tables
is a program used to manually manipulate the network
routing tables. It normally is not needed, as the
system routing table management daemon,
should tend to this task.
All commands have the following syntax:
is the destination host or network,
is the next-hop gateway to which packets should be addressed, and
is a count indicating the number of hops to
The metric is required for
commands; it must be zero if the destination is on a directly-attached network,
and nonzero if the route utilizes one or more gateways.
If adding a route with metric 0,
the gateway given is the address of this host on the common network,
indicating the interface to be used for transmission.
Routes to a particular host are distinguished from those to
a network by interpreting the Internet address associated with
force the destination to be interpreted as a network or a host, respectively.
has a ``local address part'' of INADDR_ANY,
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. If the route is to a destination connected
should be greater than 0. All symbolic names specified for a
are looked up first as a host name using
is then used to interpret the name as that of a network.
uses a raw socket and the SIOCADDRT and SIOCDELRT
to do its work. As such, only the super-user may modify
will ``flush'' the routing tables of all gateway entries.
If this is used in conjunction with one of the commands
described above, the tables are flushed prior to the command's
option prevents attempts to print host and network names symbolically
``\fBadd [ host | network ] %s: gateway %s flags %x\fP''
The specified route is being added to the tables. The
values printed are from the routing table entry supplied
If the gateway address used was not the primary address of the gateway
(the first one returned by
the gateway address is printed numerically as well as symbolically.
``\fBdelete [ host | network ] %s: gateway %s flags %x\fP''
As above, but when deleting an entry.
flag is specified, each routing table entry deleted
is indicated with a message of this form.
``\fBNetwork is unreachable\fP''
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.
A delete operation was attempted for an entry which
wasn't present in the tables.
``\fBrouting table overflow\fP''
An add operation was attempted, but the system was
low on resources and was unable to allocate memory
netintro(4), routed(8), XNSrouted(8)