ROUTE(8) BSD System Manager's Manual ROUTE(8)
NAME
route -- manually manipulate the routing tables
SYNOPSIS
route [-dnqtv] command [[modifiers] args]
DESCRIPTION
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 dis-cussed discussed
cussed in route(4).
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 con-suming, consuming,
suming, and may require correct operation of the network; thus it may be expedient to forget
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 partitionings.
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 sym-bolic symbolic
bolic 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 inter-face interface
face 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, 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 net-mask netmask
mask 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-continu-ous non-continuous
ous 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 cor-responding corresponding
responding modifiers:
-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. metamodifier.
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).
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.
DIAGNOSTICS
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 gate-way gateway
way 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 entry.
gateway uses the same route A change operation resulted in a route whose gateway uses the same route
as the one being changed. The next-hop gateway should be reachable through a different route.
The route utility exits 0 on success, and >0 if an error occurs.
SEE ALSO
netintro(4), route(4), arp(8), routed(8)
HISTORY
The route command appeared in 4.2BSD.
BUGS
The first paragraph may have slightly exaggerated routed(8)'s abilities.
4.4BSD June 8, 2001 4.4BSD
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