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1 perry 1 ROUTE
2 !!!ROUTE
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 OPTIONS
7 EXAMPLES
8 OUTPUT
9 FILES
10 SEE ALSO
11 HISTORY
12 AUTHOR
13 ----
14 !!NAME
15
16
17 route - show / manipulate the IP routing table
18 !!SYNOPSIS
19
20
21 __route__ [[__-CFvnee__]
22
23
24 __route__
25
26
27 [[__-v__] [[__-A__ family] __add__
28 [[__-net__|__-host__] target [[__netmask__ Nm]
29 [[__gw__ Gw] [[__metric__ N] [[__mss__ M]
30 [[__window__ W] [[__irtt__ I] [[__reject__]
31 [[__mod__] [[__dyn__] [[__reinstate__] [[[[__dev__]
32 If]
33
34
35 __route__
36
37
38 [[__-v__] [[__-A__ family] __del__
39 [[__-net__|__-host__] target [[__gw__ Gw]
40 [[__netmask__ Nm] [[__metric__ N] [[[[__dev__]
41 If]
42
43
44 __route__
45
46
47 [[__-V__] [[__--version__] [[__-h__]
48 [[__--help__]
49 !!DESCRIPTION
50
51
52 __Route__ manipulates the kernel's IP routing tables. Its
53 primary use is to set up static routes to specific hosts or
54 networks via an interface after it has been configured with
55 the ifconfig(8) program.
56
57
58 When the __add__ or __del__ options are used,
59 __route__ modifies the routing tables. Without these
60 options, __route__ displays the current contents of the
61 routing tables.
62 !!OPTIONS
63
64
65 __-A family__
66
67
68 use the specified address family (eg `inet'; use `route
69 --help' for a full list).
70
71
72 __-F__
73
74
75 operate on the kernel's FIB (Forwarding Information Base)
76 routing table. This is the default.
77
78
79 __-C__
80
81
82 operate on the kernel's routing cache.
83
84
85 __-v__
86
87
88 select verbose operation.
89
90
91 __-n__
92
93
94 show numerical addresses instead of trying to determine
95 symbolic host names. This is useful if you are trying to
96 determine why the route to your nameserver has
97 vanished.
98
99
100 __-e__
101
102
103 use netstat(8)-format for displaying the routing
104 table. __-ee__ will generate a very long line with all
105 parameters from the routing table.
106
107
108 __del__
109
110
111 delete a route.
112
113
114 __add__
115
116
117 add a new route.
118
119
120 __target__
121
122
123 the destination network or host. You can provide IP
124 addresses in dotted decimal or host/network
125 names.
126
127
128 __-net__
129
130
131 the __target__ is a network.
132
133
134 __-host__
135
136
137 the __target__ is a host.
138
139
140 __netmask NM__
141
142
143 when adding a network route, the netmask to be
144 used.
145
146
147 __gw GW__
148
149
150 route packets via a gateway. __NOTE:__ The specified
151 gateway must be reachable first. This usually means that you
152 have to set up a static route to the gateway beforehand. If
153 you specify the address of one of your local interfaces, it
154 will be used to decide about the interface to which the
155 packets should be routed to. This is a BSDism compatibility
156 hack.
157
158
159 __metric M__
160
161
162 set the metric field in the routing table (used by routing
163 daemons) to M.
164
165
166 __mss M__
167
168
169 set the TCP Maximum Segment Size (MSS) for connections over
170 this route to M bytes. The default is the device MTU minus
171 headers, or a lower MTU when path mtu discovery occured.
172 This setting can be used to force smaller TCP packets on the
173 other end when path mtu discovery does not work (usually
174 because of misconfigured firewalls that block ICMP
175 Fragmentation Needed)
176
177
178 __window W__
179
180
181 set the TCP window size for connections over this route to W
182 bytes. This is typically only used on AX.25 networks and
183 with drivers unable to handle back to back
184 frames.
185
186
187 __irtt I__
188
189
190 set the initial round trip time (irtt) for TCP connections
191 over this route to I milliseconds (1-12000). This is
192 typically only used on AX.25 networks. If omitted the RFC
193 1122 default of 300ms is used.
194
195
196 __reject__
197
198
199 install a blocking route, which will force a route lookup to
200 fail. This is for example used to mask out networks before
201 using the default route. This is NOT for
202 firewalling.
203
204
205 __mod, dyn, reinstate__
206
207
208 install a dynamic or modified route. These flags are for
209 diagnostic purposes, and are generally only set by routing
210 daemons.
211
212
213 __dev If__
214
215
216 force the route to be associated with the specified device,
217 as the kernel will otherwise try to determine the device on
218 its own (by checking already existing routes and device
219 specifications, and where the route is added to). In most
220 normal networks you won't need this.
221
222
223 If __dev If__ is the last option on the command line, the
224 word __dev__ may be omitted, as it's the default.
225 Otherwise the order of the route modifiers (metric - netmask
226 - gw - dev) doesn't matter.
227 !!EXAMPLES
228
229
230 __route add -net 127.0.0.0__
231
232
233 adds the normal loopback entry, using netmask 255.0.0.0
234 (class A net, determined from the destination address) and
235 associated with the
236 ifconfig__(8)).
237
238
239 __route add -net 192.56.76.0 netmask 255.255.255.0 dev
240 eth0__
241
242
243 adds a route to the network 192.56.76.x via
244
245
246 __route add default gw mango-gw__
247
248
249 adds a default route (which will be used if no other route
250 matches). All packets using this route will be gatewayed
251 through
252
253
254 __route add ipx4 sl0__
255
256
257 Adds the route to the
258
259
260 __route add -net 192.57.66.0 netmask 255.255.255.0 gw
261 ipx4__
262
263
264 This command adds the net
265
266
267 __route add -net 224.0.0.0 netmask 240.0.0.0 dev
268 eth0__
269
270
271 This is an obscure one documented so people know how to do
272 it. This sets all of the class D (multicast) IP routes to go
273 via
274
275
276 __route add -net 10.0.0.0 netmask 255.0.0.0
277 reject__
278
279
280 This installs a rejecting route for the private network
281 !!OUTPUT
282
283
284 The output of the kernel routing table is organized in the
285 following columns
286
287
288 __Destination__
289
290
291 The destination network or destination host.
292
293
294 __Gateway__
295
296
297 The gateway address or '*' if none set.
298
299
300 __Genmask__
301
302
303 The netmask for the destination net; '255.255.255.255' for a
304 host destination and '0.0.0.0' for the __default__
305 route.
306
307
308 __Flags__
309
310
311 Possible flags include__
312 U__ (route is __up__)__
313 H__ (target is a __host__)__
314 G__ (use __gateway__)__
315 R__ (__reinstate__ route for dynamic routing)__
316 D__ (__dynamically__ installed by daemon or
317 redirect)__
318 M__ (__modified__ from routing daemon or
319 redirect)__
320 A__ (installed by __addrconf__)__
321 C__ (__cache__ entry)__
322 !__ (__reject__ route)
323
324
325 __Metric__
326
327
328 The 'distance' to the target (usually counted in hops). It
329 is not used by recent kernels, but may be needed by routing
330 daemons.
331
332
333 __Ref__
334
335
336 Number of references to this route. (Not used in the Linux
337 kernel.)
338
339
340 __Use__
341
342
343 Count of lookups for the route. Depending on the use of -F
344 and -C this will be either route cache misses (-F) or hits
345 (-C).
346
347
348 __Iface__
349
350
351 Interface to which packets for this route will be
352 sent.
353
354
355 __MSS__
356
357
358 Default maximum segement size for TCP connections over this
359 route.
360
361
362 __Window__
363
364
365 Default window size for TCP connections over this
366 route.
367
368
369 __irtt__
370
371
372 Initial RTT (Round Trip Time). The kernel uses this to guess
373 about the best TCP protocol parameters without waiting on
374 (possibly slow) answers.
375
376
377 __HH (cached only)__
378
379
380 The number of ARP entries and cached routes that refer to
381 the hardware header cache for the cached route. This will be
382 -1 if a hardware address is not needed for the interface of
383 the cached route (e.g. lo).
384
385
386 __Arp (cached only)__
387
388
389 Whether or not the hardware address for the cached route is
390 up to date.
391 !!FILES
392
393
394 ''/proc/net/ipv6_route
395 /proc/net/route
396 /proc/net/rt_cache''
397 !!SEE ALSO
398
399
400 ''ifconfig(8), netstat(8), arp(8), rarp(8)''
401 !!HISTORY
402
403
404 __Route__ for Linux was originally written by Fred N. van
405 Kempen,
406 __
407 !!AUTHOR
408
409
410 Currently maintained by Phil Blundell
411 ----
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