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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.
120 The monitor command has the syntax:
122 .Bd -ragged -offset indent -compact
125 .Cm monitor Op Fl fib Ar number
128 The flush command has the syntax:
130 .Bd -ragged -offset indent -compact
132 .Oo Fl n Cm flush Oc Oo Ar family Oc Op Fl fib Ar number
137 command is specified,
139 will ``flush'' the routing tables of all gateway entries.
140 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. Additionally,
154 can be used as aliases for
161 option is specified, the operation will be applied to
165 The other commands have the following syntax:
167 .Bd -ragged -offset indent -compact
171 .Op Fl net No \&| Fl host
172 .Ar destination gateway
179 is the destination host or network,
181 is the next-hop intermediary via which packets should be routed.
182 Routes to a particular host may be distinguished from those to
183 a network by interpreting the Internet address specified as the
186 The optional modifiers
190 force the destination to be interpreted as a network or a host, respectively.
194 .Dq local address part
200 is the symbolic name of a network, then the route is
201 assumed to be to a network; otherwise, it is presumed to be a
205 could also be specified in the
206 .Ar net Ns / Ns Ar bits
212 .Fl host Li 128.0.0.32 ;
215 .Fl host Li 128.32.0.130 ;
219 .Fl net Li 128.32.130
225 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
231 is a synonym for the default route.
235 .Fl net Fl inet Li 0.0.0.0 ,
239 .Fl net Fl inet6 Li :: .
241 If the destination is directly reachable
242 via an interface requiring
243 no intermediary system to act as a gateway, the
245 modifier should be specified;
246 the gateway given is the address of this host on the common network,
247 indicating the interface to be used for transmission.
248 Alternately, if the interface is point to point the name of the interface
249 itself may be given, in which case the route remains valid even
250 if the local or remote addresses change.
252 The optional modifiers
258 specify that all subsequent addresses are in the
264 or are specified as link-level addresses,
265 and the names must be numeric specifications rather than
271 to achieve the effect of an
274 redirect with the netmask option,
275 or to manually add subnet routes with
276 netmasks different from that of the implied network interface
277 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
278 One specifies an additional ensuing address parameter
279 (to be interpreted as a network mask).
280 The implicit network mask generated in the AF_INET case
281 can be overridden by making sure this option follows the destination parameter.
288 is available instead of the
290 qualifier because non-continuous masks are not allowed in IPv6.
293 specifies network mask of
294 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
296 The default value of prefixlen is 64 to get along with
297 the aggregatable address.
301 Note that the qualifier works only for
305 Routes have associated flags which influence operation of the protocols
306 when sending to destinations matched by the routes.
307 These flags may be set (or sometimes cleared)
308 by indicating the following corresponding modifiers:
310 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
311 -iface ~RTF_GATEWAY - destination is directly reachable
312 -static RTF_STATIC - manually added route
313 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
314 -reject RTF_REJECT - emit an ICMP unreachable when matched
315 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
316 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
317 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
320 The optional modifiers
330 provide initial values to quantities maintained in the routing entry
331 by transport level protocols, such as TCP or TP4.
332 These may be individually locked by preceding each such modifier to
336 meta-modifier, or one can
337 specify that all ensuing metrics may be locked by the
341 The optional modifier
343 specifies that the command will be applied to a non-default FIB.
346 must be smaller than the
350 When this modifier is not specified,
351 or a negative number is specified,
352 the default FIB shown in the
359 allows multiple FIBs by a comma-separeted list and/or range
363 means the FIB number 2, 4, and 6.
365 .Qq Fl fib Li 1,3-5,6
366 means the 1, 3, 4, 5, and 6.
372 command where the destination and gateway are not sufficient to specify
375 case where several interfaces may have the
380 modifiers may be used to determine the interface or interface address.
382 All symbolic names specified for a
386 are looked up first as a host name using
387 .Xr gethostbyname 3 .
388 If this lookup fails,
390 is then used to interpret the name as that of a network.
394 utility uses a routing socket and the new message types
395 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
398 As such, only the super-user may modify
404 .It "add [host \&| network ] %s: gateway %s flags %x"
405 The specified route is being added to the tables.
407 values printed are from the routing table entry supplied
411 If the gateway address used was not the primary address of the gateway
412 (the first one returned by
413 .Xr gethostbyname 3 ) ,
414 the gateway address is printed numerically as well as symbolically.
415 .It "delete [ host \&| network ] %s: gateway %s flags %x"
416 As above, but when deleting an entry.
420 command is specified, each routing table entry deleted
421 is indicated with a message of this form.
422 .It "Network is unreachable"
423 An attempt to add a route failed because the gateway listed was not
424 on a directly-connected network.
425 The next-hop gateway must be given.
427 A delete operation was attempted for an entry which
428 was not present in the tables.
429 .It "routing table overflow"
430 An add operation was attempted, but the system was
431 low on resources and was unable to allocate memory
432 to create the new entry.
433 .It "gateway uses the same route"
436 operation resulted in a route whose gateway uses the
437 same route as the one being changed.
438 The next-hop gateway should be reachable through a different route.
454 The first paragraph may have slightly exaggerated
458 Currently, routes with the
460 flag set need to have the gateway set to an instance of the
464 option, for the flag to have any effect; unless IP fast forwarding
465 is enabled, in which case the meaning of the flag will always