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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
136 .Oo Fl n Cm flush Oc Oo Ar family Oc Op Fl fib Ar number
141 command is specified,
143 will ``flush'' the routing tables of all gateway entries.
144 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 other commands have the following syntax:
170 .Bd -ragged -offset indent -compact
174 .Op Fl net No \&| Fl host
175 .Ar destination gateway
182 is the destination host or network,
184 is the next-hop intermediary via which packets should be routed.
185 Routes to a particular host may be distinguished from those to
186 a network by interpreting the Internet address specified as the
189 The optional modifiers
193 force the destination to be interpreted as a network or a host, respectively.
197 .Dq local address part
203 is the symbolic name of a network, then the route is
204 assumed to be to a network; otherwise, it is presumed to be a
208 could also be specified in the
209 .Ar net Ns / Ns Ar bits
215 .Fl host Li 128.0.0.32 ;
218 .Fl host Li 128.32.0.130 ;
222 .Fl net Li 128.32.130
228 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
234 is a synonym for the default route.
238 .Fl net Fl inet Li 0.0.0.0 ,
242 .Fl net Fl inet6 Li :: .
244 If the destination is directly reachable
245 via an interface requiring
246 no intermediary system to act as a gateway, the
248 modifier should be specified;
249 the gateway given is the address of this host on the common network,
250 indicating the interface to be used for transmission.
251 Alternately, if the interface is point to point the name of the interface
252 itself may be given, in which case the route remains valid even
253 if the local or remote addresses change.
255 The optional modifiers
261 specify that all subsequent addresses are in the
267 or are specified as link-level addresses,
268 and the names must be numeric specifications rather than
274 to achieve the effect of an
277 redirect with the netmask option,
278 or to manually add subnet routes with
279 netmasks different from that of the implied network interface
280 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
281 One specifies an additional ensuing address parameter
282 (to be interpreted as a network mask).
283 The implicit network mask generated in the AF_INET case
284 can be overridden by making sure this option follows the destination parameter.
291 is available instead of the
293 qualifier because non-continuous masks are not allowed in IPv6.
296 specifies network mask of
297 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
299 The default value of prefixlen is 64 to get along with
300 the aggregatable address.
304 Note that the qualifier works only for
308 Routes have associated flags which influence operation of the protocols
309 when sending to destinations matched by the routes.
310 These flags may be set (or sometimes cleared)
311 by indicating the following corresponding modifiers:
313 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
314 -iface ~RTF_GATEWAY - destination is directly reachable
315 -static RTF_STATIC - manually added route
316 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
317 -reject RTF_REJECT - emit an ICMP unreachable when matched
318 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
319 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
320 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
321 -proto3 RTF_PROTO3 - set protocol specific routing flag #3
324 The optional modifiers
334 provide initial values to quantities maintained in the routing entry
335 by transport level protocols, such as TCP or TP4.
336 These may be individually locked by preceding each such modifier to
340 meta-modifier, or one can
341 specify that all ensuing metrics may be locked by the
347 accepts expiration time of the route as the number of seconds since the
350 When the first character of the number is
354 it is interpreted as a value relative to the current time.
356 The optional modifier
358 specifies that the command will be applied to a non-default FIB.
361 must be smaller than the
365 When this modifier is not specified,
366 or a negative number is specified,
367 the default FIB shown in the
374 allows multiple FIBs by a comma-separeted list and/or range
378 means the FIB number 2, 4, and 6.
380 .Qq Fl fib Li 1,3-5,6
381 means the 1, 3, 4, 5, and 6.
387 command where the destination and gateway are not sufficient to specify
390 case where several interfaces may have the
395 modifiers may be used to determine the interface or interface address.
397 All symbolic names specified for a
401 are looked up first as a host name using
402 .Xr gethostbyname 3 .
403 If this lookup fails,
405 is then used to interpret the name as that of a network.
409 utility uses a routing socket and the new message types
410 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
413 As such, only the super-user may modify
418 Add a default route to the network routing table.
419 This will send all packets for destinations not available in the routing table
420 to the default gateway at 192.168.1.1:
422 .Dl route add -net 0.0.0.0/0 192.168.1.1
424 A shorter version of adding a default route can also be written as:
426 .Dl route add default 192.168.1.1
428 Add a static route to the 172.16.10.0/24 network via the 172.16.1.1 gateway:
430 .Dl route add -net 172.16.10.0/24 172.16.1.1
432 Change the gateway of an already established static route in the routing table:
434 .Dl route change -net 172.16.10.0/24 172.16.1.2
436 Display the route for a destination network:
438 .Dl route show 172.16.10.0
440 Delete a static route from the routing table:
442 .Dl route delete -net 172.16.10.0/24 172.16.1.2
444 Remove all routes from the routing table:
449 .It "add [host \&| network ] %s: gateway %s flags %x"
450 The specified route is being added to the tables.
452 values printed are from the routing table entry supplied
456 If the gateway address used was not the primary address of the gateway
457 (the first one returned by
458 .Xr gethostbyname 3 ) ,
459 the gateway address is printed numerically as well as symbolically.
460 .It "delete [ host \&| network ] %s: gateway %s flags %x"
461 As above, but when deleting an entry.
465 command is specified, each routing table entry deleted
466 is indicated with a message of this form.
467 .It "Network is unreachable"
468 An attempt to add a route failed because the gateway listed was not
469 on a directly-connected network.
470 The next-hop gateway must be given.
472 A delete operation was attempted for an entry which
473 was not present in the tables.
474 .It "routing table overflow"
475 An add operation was attempted, but the system was
476 low on resources and was unable to allocate memory
477 to create the new entry.
478 .It "gateway uses the same route"
481 operation resulted in a route whose gateway uses the
482 same route as the one being changed.
483 The next-hop gateway should be reachable through a different route.
499 The first paragraph may have slightly exaggerated
503 Currently, routes with the
505 flag set need to have the gateway set to an instance of the
509 option, for the flag to have any effect; unless IP fast forwarding
510 is enabled, in which case the meaning of the flag will always