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1 | .\" Copyright (c) 1983 Regents of the University of California. |
2 | .\" All rights reserved. The Berkeley software License Agreement | |
3 | .\" specifies the terms and conditions for redistribution. | |
4 | .\" | |
438b45db | 5 | .\" @(#)routed.8 6.3 (Berkeley) %G% |
b0afce1a | 6 | .\" |
c7f51af8 | 7 | .TH ROUTED 8C "" |
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8 | .UC 5 |
9 | .SH NAME | |
10 | routed \- network routing daemon | |
11 | .SH SYNOPSIS | |
12 | .B /etc/routed | |
13 | [ | |
dfc5a452 MK |
14 | .B \-d |
15 | ] [ | |
16 | .B \-g | |
17 | ] [ | |
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18 | .B \-s |
19 | ] [ | |
20 | .B \-q | |
21 | ] [ | |
22 | .B \-t | |
23 | ] [ | |
24 | .I logfile | |
25 | ] | |
26 | .SH DESCRIPTION | |
27 | .I Routed | |
28 | is invoked at boot time to manage the network routing tables. | |
29 | The routing daemon uses a variant of the Xerox NS Routing | |
30 | Information Protocol in maintaining up to date kernel routing | |
31 | table entries. | |
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32 | It used a generalized protocol capable of use with multiple |
33 | address types, but is currently used only for Internet routing | |
34 | within a cluster of networks. | |
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35 | .PP |
36 | In normal operation | |
37 | .I routed | |
dfc5a452 | 38 | listens on the |
b0afce1a | 39 | .IR udp (4P) |
dfc5a452 MK |
40 | socket for the |
41 | .I route | |
42 | service (see | |
43 | .IR services (5)) | |
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44 | for routing information packets. If the host is an |
45 | internetwork router, it periodically supplies copies | |
46 | of its routing tables to any directly connected hosts | |
47 | and networks. | |
48 | .PP | |
49 | When | |
50 | .I routed | |
51 | is started, it uses the SIOCGIFCONF | |
52 | .I ioctl | |
53 | to find those | |
54 | directly connected interfaces configured into the | |
55 | system and marked ``up'' (the software loopback interface | |
56 | is ignored). If multiple interfaces | |
dfc5a452 | 57 | are present, it is assumed that the host will forward packets |
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58 | between networks. |
59 | .I Routed | |
60 | then transmits a | |
61 | .I request | |
62 | packet on each interface (using a broadcast packet if | |
63 | the interface supports it) and enters a loop, listening | |
64 | for | |
65 | .I request | |
66 | and | |
67 | .I response | |
68 | packets from other hosts. | |
69 | .PP | |
70 | When a | |
71 | .I request | |
72 | packet is received, | |
73 | .I routed | |
74 | formulates a reply based on the information maintained in its | |
75 | internal tables. The | |
76 | .I response | |
77 | packet generated contains a list of known routes, each marked | |
78 | with a ``hop count'' metric (a count of 16, or greater, is | |
79 | considered ``infinite''). The metric associated with each | |
80 | route returned provides a metric | |
81 | .IR "relative to the sender" . | |
82 | .PP | |
83 | .I Response | |
84 | packets received by | |
85 | .I routed | |
86 | are used to update the routing tables if one of the following | |
87 | conditions is satisfied: | |
88 | .TP | |
89 | (1) | |
90 | No routing table entry exists for the destination network | |
91 | or host, and the metric indicates the destination is ``reachable'' | |
92 | (i.e. the hop count is not infinite). | |
93 | .TP | |
94 | (2) | |
95 | The source host of the packet is the same as the router in the | |
96 | existing routing table entry. That is, updated information is | |
97 | being received from the very internetwork router through which | |
98 | packets for the destination are being routed. | |
99 | .TP | |
100 | (3) | |
101 | The existing entry in the routing table has not been updated for | |
102 | some time (defined to be 90 seconds) and the route is at least | |
103 | as cost effective as the current route. | |
104 | .TP | |
105 | (4) | |
106 | The new route describes a shorter route to the destination than | |
107 | the one currently stored in the routing tables; the metric of | |
108 | the new route is compared against the one stored in the table | |
109 | to decide this. | |
110 | .PP | |
111 | When an update is applied, | |
112 | .I routed | |
dfc5a452 MK |
113 | records the change in its internal tables and updates the kernel |
114 | routing table. | |
115 | The change is reflected in the next | |
b0afce1a | 116 | .I response |
dfc5a452 | 117 | packet sent. |
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118 | .PP |
119 | In addition to processing incoming packets, | |
120 | .I routed | |
121 | also periodically checks the routing table entries. | |
122 | If an entry has not been updated for 3 minutes, the entry's metric | |
123 | is set to infinity and marked for deletion. Deletions are delayed | |
124 | an additional 60 seconds to insure the invalidation is propagated | |
dfc5a452 | 125 | throughout the local internet. |
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126 | .PP |
127 | Hosts acting as internetwork routers gratuitously supply their | |
128 | routing tables every 30 seconds to all directly connected hosts | |
129 | and networks. | |
dfc5a452 MK |
130 | The response is sent to the broadcast address on nets capable of that function, |
131 | to the destination address on point-to-point links, and to the router's | |
132 | own address on other networks. | |
133 | The normal routing tables are bypassed when sending gratuitous responses. | |
134 | The reception of responses on each network is used to determine that the | |
135 | network and interface are functioning correctly. | |
136 | If no response is received on an interface, another route may be chosen | |
137 | to route around the interface, or the route may be dropped if no alternative | |
138 | is available. | |
b0afce1a | 139 | .PP |
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140 | .I Routed supports several options: |
141 | .TP | |
142 | .B \-d | |
143 | Enable additional debugging information to be logged, | |
144 | such as bad packets received. | |
145 | .TP | |
146 | .B \-g | |
147 | This flag is used on internetwork routers to offer a route | |
148 | to the ``default'' destination. | |
149 | This is typically used on a gateway to the Internet, | |
150 | or on a gateway that uses another routing protocol whose routes | |
151 | are not reported to other local routers. | |
152 | .TP | |
b0afce1a | 153 | .B \-s |
dfc5a452 | 154 | Supplying this |
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155 | option forces |
156 | .I routed | |
157 | to supply routing information whether it is acting as an internetwork | |
158 | router or not. | |
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159 | This is the default if multiple network interfaces are present, |
160 | or if a point-to-point link is in use. | |
161 | .TP | |
b0afce1a | 162 | .B \-q |
dfc5a452 MK |
163 | This |
164 | is the opposite of the | |
b0afce1a | 165 | .B \-s |
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166 | option. |
167 | .TP | |
168 | .B \-t | |
169 | If the | |
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170 | .B \-t |
171 | option is specified, all packets sent or received are | |
172 | printed on the standard output. In addition, | |
173 | .I routed | |
174 | will not divorce itself from the controlling terminal | |
175 | so that interrupts from the keyboard will kill the process. | |
dfc5a452 | 176 | .PP |
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177 | Any other argument supplied is interpreted as the name |
178 | of file in which | |
179 | .IR routed 's | |
180 | actions should be logged. This log contains information | |
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181 | about any changes to the routing tables and, if not tracing all packets, |
182 | a history of recent messages sent and received which are related to | |
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183 | the changed route. |
184 | .PP | |
185 | In addition to the facilities described above, | |
186 | .I routed | |
187 | supports the notion of ``distant'' | |
188 | .I passive | |
189 | and | |
190 | .I active | |
191 | gateways. When | |
192 | .I routed | |
193 | is started up, it reads the file | |
194 | .I /etc/gateways | |
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195 | to find gateways which may not be located using |
196 | only information from the SIOGIFCONF | |
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197 | .IR ioctl . |
198 | Gateways specified in this manner should be marked passive | |
199 | if they are not expected to exchange routing information, | |
200 | while gateways marked active | |
201 | should be willing to exchange routing information (i.e. | |
202 | they should have a | |
203 | .I routed | |
204 | process running on the machine). | |
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205 | Routes through passive gateways are installed in the |
206 | kernel's routing tables once upon startup. | |
207 | Such routes are not included in | |
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208 | any routing information transmitted. |
209 | Active gateways are treated equally to network | |
210 | interfaces. Routing information is distributed | |
211 | to the gateway and if no routing information is | |
212 | received for a period of the time, the associated | |
213 | route is deleted. | |
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214 | Gateways marked |
215 | .I external | |
216 | are also passive, but are not placed in the kernel | |
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217 | routing table nor are they included in routing updates. |
218 | The function of external entries is to inform | |
219 | .I routed | |
220 | that another routing process | |
221 | will install such a route, and that alternate routes to that destination | |
222 | should not be installed. | |
223 | Such entries are only required when both routers may learn of routes | |
224 | to the same destination. | |
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225 | .PP |
226 | The | |
227 | .I /etc/gateways | |
228 | is comprised of a series of lines, each in | |
229 | the following format: | |
230 | .PP | |
231 | .nf | |
dfc5a452 | 232 | < \fBnet\fP | \fBhost\fP > \fIname1\fP \fBgateway\fP \fIname2\fP \fBmetric\fP \fIvalue\fP < \fBpassive\fP | \fBactive\fP | \fBexternal\fP > |
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233 | .fi |
234 | .PP | |
235 | The | |
236 | .B net | |
237 | or | |
238 | .B host | |
239 | keyword indicates if the route is to a network or specific host. | |
240 | .PP | |
241 | .I Name1 | |
242 | is the name of the destination network or host. This may be a | |
243 | symbolic name located in | |
244 | .I /etc/networks | |
245 | or | |
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246 | .I /etc/hosts |
247 | (or, if started after | |
248 | .IR named (8), | |
249 | known to the name server), | |
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250 | or an Internet address specified in ``dot'' notation; see |
251 | .IR inet (3N). | |
252 | .PP | |
253 | .I Name2 | |
254 | is the name or address of the gateway to which messages should | |
255 | be forwarded. | |
256 | .PP | |
257 | .I Value | |
258 | is a metric indicating the hop count to the destination host | |
259 | or network. | |
260 | .PP | |
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261 | One of the keywords |
262 | .BR passive , | |
b0afce1a | 263 | .B active |
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264 | or |
265 | .B external | |
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266 | indicates if the gateway should be treated as |
267 | .I passive | |
268 | or | |
269 | .I active | |
dfc5a452 | 270 | (as described above), |
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271 | or whether the gateway is |
272 | .I external | |
273 | to the scope of the | |
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274 | .I routed |
275 | protocol. | |
276 | .PP | |
277 | Internetwork routers that are directly attached to the Arpanet or Milnet | |
278 | should use the Exterior Gateway Protocol (EGP) to gather routing information | |
279 | rather then using a static routing table of passive gateways. | |
280 | EGP is required in order to provide routes for local networks to the rest | |
281 | of the Internet system. | |
282 | Sites needing assistance with such configurations | |
283 | should contact the Computer Systems Research Group at Berkeley. | |
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284 | .SH FILES |
285 | .DT | |
286 | /etc/gateways for distant gateways | |
287 | .SH "SEE ALSO" | |
288 | ``Internet Transport Protocols'', XSIS 028112, Xerox System Integration | |
289 | Standard. | |
290 | .br | |
438b45db | 291 | udp(4P), icmp(4P), XNSrouted(8C), htable(8) |
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292 | .SH BUGS |
293 | The kernel's routing tables may not correspond to those of | |
294 | .I routed | |
dfc5a452 | 295 | when redirects change or add routes. |
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296 | .I Routed |
297 | should note any redirects received by reading | |
298 | the ICMP packets received via a raw socket. | |
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299 | .PP |
300 | .I Routed | |
dfc5a452 MK |
301 | should incorporate other routing protocols, |
302 | such as Xerox NS | |
303 | .RI ( XNSrouted (8C)) | |
304 | and EGP. | |
305 | Using separate processes for each requires configuration options | |
306 | to avoid redundant or competing routes. | |
307 | .PP | |
308 | .I Routed | |
438b45db MK |
309 | should listen to intelligent interfaces, such as an IMP, |
310 | to gather more information. | |
dfc5a452 MK |
311 | It does not always detect unidirectional failures in network interfaces |
312 | (e.g., when the output side fails). |