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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
151 modifiers, only routes having destinations with addresses in the
152 delineated family will be deleted.
157 can be used as aliases for
164 option is specified, the operation will be applied to
168 The add command has the following syntax:
170 .Bd -ragged -offset indent -compact
174 .Op Fl net No \&| Fl host
175 .Ar destination gateway
180 and the other commands have the following syntax:
182 .Bd -ragged -offset indent -compact
186 .Op Fl net No \&| Fl host
188 .Op Ar gateway Op Ar netmask
194 is the destination host or network,
196 is the next-hop intermediary via which packets should be routed.
197 Routes to a particular host may be distinguished from those to
198 a network by interpreting the Internet address specified as the
201 The optional modifiers
205 force the destination to be interpreted as a network or a host, respectively.
209 .Dq local address part
215 is the symbolic name of a network, then the route is
216 assumed to be to a network; otherwise, it is presumed to be a
220 could also be specified in the
221 .Ar net Ns / Ns Ar bits
227 .Fl host Li 128.0.0.32 ;
230 .Fl host Li 128.32.0.130 ;
234 .Fl net Li 128.32.130
240 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
246 is a synonym for the default route.
250 .Fl net Fl inet Li 0.0.0.0 ,
254 .Fl net Fl inet6 Li :: .
256 If the destination is directly reachable
257 via an interface requiring
258 no intermediary system to act as a gateway, the
260 modifier should be specified;
261 the gateway given is the address of this host on the common network,
262 indicating the interface to be used for transmission.
263 Alternately, if the interface is point to point the name of the interface
264 itself may be given, in which case the route remains valid even
265 if the local or remote addresses change.
267 The optional modifiers
272 specify that all subsequent addresses are in the
277 or are specified as link-level addresses,
278 and the names must be numeric specifications rather than
284 to achieve the effect of an
287 redirect with the netmask option,
288 or to manually add subnet routes with
289 netmasks different from that of the implied network interface
290 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
291 One specifies an additional ensuing address parameter
292 (to be interpreted as a network mask).
293 The implicit network mask generated in the AF_INET case
294 can be overridden by making sure this option follows the destination parameter.
301 is available instead of the
303 qualifier because non-continuous masks are not allowed in IPv6.
306 specifies that a network mask of
307 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
309 The default prefixlen is 64.
310 However, it is assumed to be 0 if
314 Note that the qualifier works only for
318 Routes have associated flags which influence operation of the protocols
319 when sending to destinations matched by the routes.
320 These flags may be set (or sometimes cleared)
321 by indicating the following corresponding modifiers:
323 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
324 -iface ~RTF_GATEWAY - destination is directly reachable
325 -static RTF_STATIC - manually added route
326 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
327 -reject RTF_REJECT - emit an ICMP unreachable when matched
328 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
329 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
330 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
333 The optional modifiers
343 provide initial values to quantities maintained in the routing entry
344 by transport level protocols, such as TCP or TP4.
345 These may be individually locked by preceding each such modifier to
349 meta-modifier, or one can
350 specify that all ensuing metrics may be locked by the
356 accepts expiration time of the route as the number of seconds since the
359 When the first character of the number is
363 it is interpreted as a value relative to the current time.
365 The optional modifier
367 specifies that the command will be applied to a non-default FIB.
370 must be smaller than the
374 When this modifier is not specified,
375 or a negative number is specified,
376 the default FIB shown in the
383 allows multiple FIBs by a comma-separeted list and/or range
387 means the FIB number 2, 4, and 6.
389 .Qq Fl fib Li 1,3-5,6
390 means the 1, 3, 4, 5, and 6.
396 command where the destination and gateway are not sufficient to specify
399 case where several interfaces may have the
404 modifiers may be used to determine the interface or interface address.
406 All symbolic names specified for a
410 are looked up first as a host name using
411 .Xr gethostbyname 3 .
412 If this lookup fails,
414 is then used to interpret the name as that of a network.
418 utility uses a routing socket and the new message types
419 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
422 As such, only the super-user may modify
427 Add a default route to the network routing table.
428 This will send all packets for destinations not available in the routing table
429 to the default gateway at 192.168.1.1:
431 .Dl route add -net 0.0.0.0/0 192.168.1.1
433 A shorter version of adding a default route can also be written as:
435 .Dl route add default 192.168.1.1
437 Add a static route to the 172.16.10.0/24 network via the 172.16.1.1 gateway:
439 .Dl route add -net 172.16.10.0/24 172.16.1.1
441 Change the gateway of an already established static route in the routing table:
443 .Dl route change -net 172.16.10.0/24 172.16.1.2
445 Display the route for a destination network:
447 .Dl route show 172.16.10.0
449 Delete a static route from the routing table:
451 .Dl route delete -net 172.16.10.0/24 172.16.1.2
453 Remove all routes from the routing table:
458 .It "add [host \&| network ] %s: gateway %s flags %x"
459 The specified route is being added to the tables.
461 values printed are from the routing table entry supplied
465 If the gateway address used was not the primary address of the gateway
466 (the first one returned by
467 .Xr gethostbyname 3 ) ,
468 the gateway address is printed numerically as well as symbolically.
469 .It "delete [ host \&| network ] %s: gateway %s flags %x"
470 As above, but when deleting an entry.
474 command is specified, each routing table entry deleted
475 is indicated with a message of this form.
476 .It "Network is unreachable"
477 An attempt to add a route failed because the gateway listed was not
478 on a directly-connected network.
479 The next-hop gateway must be given.
481 A delete operation was attempted for an entry which
482 was not present in the tables.
483 .It "routing table overflow"
484 An add operation was attempted, but the system was
485 low on resources and was unable to allocate memory
486 to create the new entry.
487 .It "gateway uses the same route"
490 operation resulted in a route whose gateway uses the
491 same route as the one being changed.
492 The next-hop gateway should be reachable through a different route.
507 The first paragraph may have slightly exaggerated
511 Currently, routes with the
513 flag set need to have the gateway set to an instance of the
517 option, for the flag to have any effect; unless IP fast forwarding
518 is enabled, in which case the meaning of the flag will always