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28 .\" @(#)route.8 8.3 (Berkeley) 3/19/94
36 .Nd manually manipulate the routing tables
48 utility is used to manually manipulate the network
50 It normally is not needed, as a
51 system routing table management daemon, such as
53 should tend to this task.
57 utility supports a limited number of general options,
58 but a rich command language, enabling the user to specify
59 any arbitrary request that could be delivered via the
60 programmatic interface discussed in
63 The following options are available:
64 .Bl -tag -width indent
68 address family as family hint for subcommands.
72 address family as family hint for subcommands.
74 Run in debug-only mode, i.e., do not actually modify the routing table.
76 Bypass attempts to print host and network names symbolically
77 when reporting actions.
78 (The process of translating between symbolic
79 names and numerical equivalents can be quite time consuming, and
80 may require correct operation of the network; thus it may be expedient
81 to forget this, especially when attempting to repair networking operations).
83 Run in test-only mode.
85 is used instead of a socket.
87 (verbose) Print additional details.
89 Suppress all output from the
90 .Cm add , change , delete ,
98 utility provides the following commands:
100 .Bl -tag -width Fl -compact
106 Delete a specific route.
112 Change aspects of a route (such as its gateway).
114 Lookup and display the route for a destination.
116 Continuously report any changes to the routing information base,
117 routing lookup misses, or suspected network partitionings.
124 The monitor command has the syntax:
126 .Bd -ragged -offset indent -compact
129 .Cm monitor Op Fl fib Ar number
132 The flush command has the syntax:
134 .Bd -ragged -offset indent -compact
137 .Cm flush Oc Oo Ar family Oc Op Fl fib Ar number
142 command is specified,
144 will ``flush'' the routing tables of all gateway entries.
145 When the address family may is specified by any of the
149 modifiers, only routes having destinations with addresses in the
150 delineated family will be deleted.
155 can be used as aliases for
162 option is specified, the operation will be applied to
166 The add command has the following syntax:
168 .Bd -ragged -offset indent -compact
172 .Op Fl net No \&| Fl host
173 .Ar destination gateway
178 and the other commands have the following syntax:
180 .Bd -ragged -offset indent -compact
184 .Op Fl net No \&| Fl host
186 .Op Ar gateway Op Ar netmask
192 is the destination host or network,
194 is the next-hop intermediary via which packets should be routed.
195 Routes to a particular host may be distinguished from those to
196 a network by interpreting the Internet address specified as the
199 The optional modifiers
203 force the destination to be interpreted as a network or a host, respectively.
207 .Dq local address part
213 is the symbolic name of a network, then the route is
214 assumed to be to a network; otherwise, it is presumed to be a
218 could also be specified in the
219 .Ar net Ns / Ns Ar bits
225 .Fl host Li 128.0.0.32 ;
228 .Fl host Li 128.32.0.130 ;
232 .Fl net Li 128.32.130
238 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
244 is a synonym for the default route.
248 .Fl net Fl inet Li 0.0.0.0 ,
252 .Fl net Fl inet6 Li :: .
254 If the destination is directly reachable
255 via an interface requiring
256 no intermediary system to act as a gateway, the
258 modifier should be specified;
259 the gateway given is the address of this host on the common network,
260 indicating the interface to be used for transmission.
261 Alternately, if the interface is point to point the name of the interface
262 itself may be given, in which case the route remains valid even
263 if the local or remote addresses change.
268 to achieve the effect of an
271 redirect with the netmask option,
272 or to manually add subnet routes with
273 netmasks different from that of the implied network interface
274 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
275 One specifies an additional ensuing address parameter
276 (to be interpreted as a network mask).
277 The implicit network mask generated in the AF_INET case
278 can be overridden by making sure this option follows the destination parameter.
285 is available instead of the
287 qualifier because non-continuous masks are not allowed in IPv6.
290 specifies that a network mask of
291 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
293 The default prefixlen is 64.
294 However, it is assumed to be 0 if
298 Note that the qualifier works only for
302 Routes have associated flags which influence operation of the protocols
303 when sending to destinations matched by the routes.
304 These flags may be set (or sometimes cleared)
305 by indicating the following corresponding modifiers:
307 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
308 -iface ~RTF_GATEWAY - destination is directly reachable
309 -static RTF_STATIC - manually added route
310 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
311 -reject RTF_REJECT - emit an ICMP unreachable when matched
312 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
313 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
314 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
317 The optional modifiers
327 provide initial values to quantities maintained in the routing entry
328 by transport level protocols, such as TCP or TP4.
329 These may be individually locked by preceding each such modifier to
333 meta-modifier, or one can
334 specify that all ensuing metrics may be locked by the
340 accepts expiration time of the route as the number of seconds since the
343 When the first character of the number is
347 it is interpreted as a value relative to the current time.
349 The optional modifier
351 specifies that the command will be applied to a non-default FIB.
354 must be smaller than the
358 When this modifier is not specified,
359 or a negative number is specified,
360 the default FIB shown in the
367 allows multiple FIBs by a comma-separeted list and/or range
371 means the FIB number 2, 4, and 6.
373 .Qq Fl fib Li 1,3-5,6
374 means the 1, 3, 4, 5, and 6.
380 command where the destination and gateway are not sufficient to specify
383 case where several interfaces may have the
388 modifiers may be used to determine the interface or interface address.
390 All symbolic names specified for a
394 are looked up first as a host name using
395 .Xr gethostbyname 3 .
396 If this lookup fails,
398 is then used to interpret the name as that of a network.
402 utility uses a routing socket and the new message types
403 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
406 As such, only the super-user may modify
411 Add a default route to the network routing table.
412 This will send all packets for destinations not available in the routing table
413 to the default gateway at 192.168.1.1:
415 .Dl route add -net 0.0.0.0/0 192.168.1.1
417 A shorter version of adding a default route can also be written as:
419 .Dl route add default 192.168.1.1
421 Add a static route to the 172.16.10.0/24 network via the 172.16.1.1 gateway:
423 .Dl route add -net 172.16.10.0/24 172.16.1.1
425 Change the gateway of an already established static route in the routing table:
427 .Dl route change -net 172.16.10.0/24 172.16.1.2
429 Display the route for a destination network:
431 .Dl route show 172.16.10.0
433 Delete a static route from the routing table:
435 .Dl route delete -net 172.16.10.0/24 172.16.1.2
437 Remove all routes from the routing table:
441 List all routing tables:
446 .It "add [host \&| network ] %s: gateway %s flags %x"
447 The specified route is being added to the tables.
449 values printed are from the routing table entry supplied
453 If the gateway address used was not the primary address of the gateway
454 (the first one returned by
455 .Xr gethostbyname 3 ) ,
456 the gateway address is printed numerically as well as symbolically.
457 .It "delete [ host \&| network ] %s: gateway %s flags %x"
458 As above, but when deleting an entry.
462 command is specified, each routing table entry deleted
463 is indicated with a message of this form.
464 .It "Network is unreachable"
465 An attempt to add a route failed because the gateway listed was not
466 on a directly-connected network.
467 The next-hop gateway must be given.
469 A delete operation was attempted for an entry which
470 was not present in the tables.
471 .It "routing table overflow"
472 An add operation was attempted, but the system was
473 low on resources and was unable to allocate memory
474 to create the new entry.
475 .It "gateway uses the same route"
478 operation resulted in a route whose gateway uses the
479 same route as the one being changed.
480 The next-hop gateway should be reachable through a different route.
495 The first paragraph may have slightly exaggerated
499 Currently, routes with the
501 flag set need to have the gateway set to an instance of the
505 option, for the flag to have any effect; unless IP fast forwarding
506 is enabled, in which case the meaning of the flag will always