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32 .\" @(#)route.8 8.3 (Berkeley) 3/19/94
33 .\" $FreeBSD: src/sbin/route/route.8,v 1.17.2.9 2003/02/24 00:56:43 trhodes Exp $
40 .Nd manually manipulate the routing tables
52 utility is used to manually manipulate the network
53 routing tables. It normally is not needed, as a
54 system routing table management daemon such as
56 should tend to this task.
60 utility supports a limited number of general options,
61 but a rich command language, enabling the user to specify
62 any arbitrary request that could be delivered via the
63 programmatic interface discussed in
66 The following options are available:
67 .Bl -tag -width indent
69 Bypass attempts to print host and network names symbolically
70 when reporting actions. (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 (verbose) Print additional details.
77 Suppress all output from the
86 utility provides six commands:
88 .Bl -tag -width Fl -compact
94 Delete a specific route.
96 Change aspects of a route (such as its gateway).
98 Lookup and display the route for a destination.
100 Continuously report any changes to the routing information base,
101 routing lookup misses, or suspected network partitionings.
104 The monitor command has the syntax:
106 .Bd -ragged -offset indent -compact
112 The flush command has the syntax:
114 .Bd -ragged -offset indent -compact
123 command is specified,
125 will ``flush'' the routing tables of all gateway entries.
126 When the address family may is specified by any of the
133 modifiers, only routes having destinations with addresses in the
134 delineated family will be deleted.
136 The other commands have the following syntax:
138 .Bd -ragged -offset indent -compact
142 .Op Fl net No \&| Fl host
143 .Ar destination gateway
149 is the destination host or network,
151 is the next-hop intermediary via which packets should be routed.
152 Routes to a particular host may be distinguished from those to
153 a network by interpreting the Internet address specified as the
156 The optional modifiers
160 force the destination to be interpreted as a network or a host, respectively.
164 .Dq local address part
170 is the symbolic name of a network, then the route is
171 assumed to be to a network; otherwise, it is presumed to be a
175 could also be specified in the
176 .Ar net Ns / Ns Ar bits
182 .Fl host Li 128.0.0.32 ;
185 .Fl host Li 128.32.0.130 ;
189 .Fl net Li 128.32.130
195 .Fl net Li 192.168.64 Fl netmask Li 255.255.240.0 .
203 which is the default route.
205 If the destination is directly reachable
206 via an interface requiring
207 no intermediary system to act as a gateway, the
209 modifier should be specified;
210 the gateway given is the address of this host on the common network,
211 indicating the interface to be used for transmission.
212 Alternately, if the interface is point to point the name of the interface
213 itself may be given, in which case the route remains valid even
214 if the local or remote addresses change.
216 The optional modifiers
222 specify that all subsequent addresses are in the
228 or are specified as link-level addresses,
229 and the names must be numeric specifications rather than
235 to achieve the effect of an
238 redirect with the netmask option,
239 or to manually add subnet routes with
240 netmasks different from that of the implied network interface
241 (as would otherwise be communicated using the OSPF or ISIS routing protocols).
242 One specifies an additional ensuing address parameter
243 (to be interpreted as a network mask).
244 The implicit network mask generated in the AF_INET case
245 can be overridden by making sure this option follows the destination parameter.
252 is available instead of the
254 qualifier because non-continuous masks are not allowed in IPv6.
257 specifies network mask of
258 .Li ffff:ffff:0000:0000:0000:0000:0000:0000
260 The default value of prefixlen is 64 to get along with
261 the aggregatable address.
265 Note that the qualifier works only for
269 Routes have associated flags which influence operation of the protocols
270 when sending to destinations matched by the routes.
271 These flags may be set (or sometimes cleared)
272 by indicating the following corresponding modifiers:
274 -cloning RTF_CLONING - generates a new route on use
275 -xresolve RTF_XRESOLVE - emit mesg on use (for external lookup)
276 -iface ~RTF_GATEWAY - destination is directly reachable
277 -static RTF_STATIC - manually added route
278 -nostatic ~RTF_STATIC - pretend route added by kernel or daemon
279 -reject RTF_REJECT - emit an ICMP unreachable when matched
280 -blackhole RTF_BLACKHOLE - silently discard pkts (during updates)
281 -proto1 RTF_PROTO1 - set protocol specific routing flag #1
282 -proto2 RTF_PROTO2 - set protocol specific routing flag #2
283 -llinfo RTF_LLINFO - validly translates proto addr to link addr
286 The optional modifiers
296 provide initial values to quantities maintained in the routing entry
297 by transport level protocols, such as TCP or TP4.
298 These may be individually locked by preceding each such modifier to
302 meta-modifier, or one can
303 specify that all ensuing metrics may be locked by the
311 command where the destination and gateway are not sufficient to specify
314 case where several interfaces may have the
319 modifiers may be used to determine the interface or interface address.
323 modifier specifies that the
325 routing table entry is the
326 .Dq published (proxy-only)
328 entry, as reported by
331 All symbolic names specified for a
335 are looked up first as a host name using
336 .Xr gethostbyname 3 .
337 If this lookup fails,
339 is then used to interpret the name as that of a network.
343 utility uses a routing socket and the new message types
344 .Dv RTM_ADD , RTM_DELETE , RTM_GET ,
347 As such, only the super-user may modify
351 .It "add [host \&| network ] %s: gateway %s flags %x"
352 The specified route is being added to the tables. The
353 values printed are from the routing table entry supplied
357 If the gateway address used was not the primary address of the gateway
358 (the first one returned by
359 .Xr gethostbyname 3 ) ,
360 the gateway address is printed numerically as well as symbolically.
361 .It "delete [ host \&| network ] %s: gateway %s flags %x"
362 As above, but when deleting an entry.
366 command is specified, each routing table entry deleted
367 is indicated with a message of this form.
368 .It "Network is unreachable"
369 An attempt to add a route failed because the gateway listed was not
370 on a directly-connected network.
371 The next-hop gateway must be given.
373 A delete operation was attempted for an entry which
374 wasn't present in the tables.
375 .It "routing table overflow"
376 An add operation was attempted, but the system was
377 low on resources and was unable to allocate memory
378 to create the new entry.
379 .It "gateway uses the same route"
382 operation resulted in a route whose gateway uses the
383 same route as the one being changed.
384 The next-hop gateway should be reachable through a different route.
402 The first paragraph may have slightly exaggerated