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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
66 Run in debug-only mode, i.e., do not actually modify the routing table.
68 Bypass attempts to print host and network names symbolically
69 when reporting actions.
70 (The process of translating between symbolic
71 names and numerical equivalents can be quite time consuming, and
72 may require correct operation of the network; thus it may be expedient
73 to forget this, especially when attempting to repair networking operations).
75 Run in test-only mode.
77 is used instead of a socket.
79 (verbose) Print additional details.
81 Suppress all output from the
82 .Cm add , change , delete ,
90 utility provides the following commands:
92 .Bl -tag -width Fl -compact
98 Delete a specific route.
104 Change aspects of a route (such as its gateway).
106 Lookup and display the route for a destination.
108 Continuously report any changes to the routing information base,
109 routing lookup misses, or suspected network partitionings.
112 The monitor command has the syntax:
114 .Bd -ragged -offset indent -compact
117 .Cm monitor Op Fl fib Ar number
120 The flush command has the syntax:
122 .Bd -ragged -offset indent -compact
124 .Oo Fl n Cm flush Oc Oo Ar family Oc Op Fl fib Ar number
129 command is specified,
131 will ``flush'' the routing tables of all gateway entries.
132 When the address family may is specified by any of the
139 modifiers, only routes having destinations with addresses in the
140 delineated family will be deleted.
143 option is specified, the operation will be applied to
147 The other commands have the following syntax:
149 .Bd -ragged -offset indent -compact
153 .Op Fl net No \&| Fl host
154 .Ar destination gateway
161 is the destination host or network,
163 is the next-hop intermediary via which packets should be routed.
164 Routes to a particular host may be distinguished from those to
165 a network by interpreting the Internet address specified as the
168 The optional modifiers
172 force the destination to be interpreted as a network or a host, respectively.
176 .Dq local address part
182 is the symbolic name of a network, then the route is
183 assumed to be to a network; otherwise, it is presumed to be a
187 could also be specified in the
188 .Ar net Ns / Ns Ar bits
194 .Fl host Li 128.0.0.32 ;
197 .Fl host Li 128.32.0.130 ;
201 .Fl net Li 128.32.130
207 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
213 is a synonym for the default route.
217 .Fl net Fl inet Li 0.0.0.0 ,
221 .Fl net Fl inet6 Li :: .
223 If the destination is directly reachable
224 via an interface requiring
225 no intermediary system to act as a gateway, the
227 modifier should be specified;
228 the gateway given is the address of this host on the common network,
229 indicating the interface to be used for transmission.
230 Alternately, if the interface is point to point the name of the interface
231 itself may be given, in which case the route remains valid even
232 if the local or remote addresses change.
234 The optional modifiers
240 specify that all subsequent addresses are in the
246 or are specified as link-level addresses,
247 and the names must be numeric specifications rather than
253 to achieve the effect of an
256 redirect with the netmask option,
257 or to manually add subnet routes with
258 netmasks different from that of the implied network interface
259 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
260 One specifies an additional ensuing address parameter
261 (to be interpreted as a network mask).
262 The implicit network mask generated in the AF_INET case
263 can be overridden by making sure this option follows the destination parameter.
270 is available instead of the
272 qualifier because non-continuous masks are not allowed in IPv6.
275 specifies network mask of
276 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
278 The default value of prefixlen is 64 to get along with
279 the aggregatable address.
283 Note that the qualifier works only for
287 Routes have associated flags which influence operation of the protocols
288 when sending to destinations matched by the routes.
289 These flags may be set (or sometimes cleared)
290 by indicating the following corresponding modifiers:
292 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
293 -iface ~RTF_GATEWAY - destination is directly reachable
294 -static RTF_STATIC - manually added route
295 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
296 -reject RTF_REJECT - emit an ICMP unreachable when matched
297 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
298 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
299 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
302 The optional modifiers
312 provide initial values to quantities maintained in the routing entry
313 by transport level protocols, such as TCP or TP4.
314 These may be individually locked by preceding each such modifier to
318 meta-modifier, or one can
319 specify that all ensuing metrics may be locked by the
323 The optional modifier
325 specifies that the command will be applied to a non-default FIB.
328 must be smaller than the
332 When this modifier is not specified,
333 or a negative number is specified,
334 the default FIB shown in the
341 allows multiple FIBs by a comma-separeted list and/or range
345 means the FIB number 2, 4, and 6.
347 .Qq Fl fib Li 1,3-5,6
348 means the 1, 3, 4, 5, and 6.
354 command where the destination and gateway are not sufficient to specify
357 case where several interfaces may have the
362 modifiers may be used to determine the interface or interface address.
364 All symbolic names specified for a
368 are looked up first as a host name using
369 .Xr gethostbyname 3 .
370 If this lookup fails,
372 is then used to interpret the name as that of a network.
376 utility uses a routing socket and the new message types
377 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
380 As such, only the super-user may modify
386 .It "add [host \&| network ] %s: gateway %s flags %x"
387 The specified route is being added to the tables.
389 values printed are from the routing table entry supplied
393 If the gateway address used was not the primary address of the gateway
394 (the first one returned by
395 .Xr gethostbyname 3 ) ,
396 the gateway address is printed numerically as well as symbolically.
397 .It "delete [ host \&| network ] %s: gateway %s flags %x"
398 As above, but when deleting an entry.
402 command is specified, each routing table entry deleted
403 is indicated with a message of this form.
404 .It "Network is unreachable"
405 An attempt to add a route failed because the gateway listed was not
406 on a directly-connected network.
407 The next-hop gateway must be given.
409 A delete operation was attempted for an entry which
410 was not present in the tables.
411 .It "routing table overflow"
412 An add operation was attempted, but the system was
413 low on resources and was unable to allocate memory
414 to create the new entry.
415 .It "gateway uses the same route"
418 operation resulted in a route whose gateway uses the
419 same route as the one being changed.
420 The next-hop gateway should be reachable through a different route.
436 The first paragraph may have slightly exaggerated
440 Currently, routes with the
442 flag set need to have the gateway set to an instance of the
446 option, for the flag to have any effect; unless IP fast forwarding
447 is enabled, in which case the meaning of the flag will always