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1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
4 <!-- The content of this document is licensed under the CC-BY-SA license -->
5 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
6
7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-net-modules.xml,v 1.8 2005/09/07 19:00:28 jkt Exp $ -->
8
9 <sections>
10
11 <version>1.4</version>
12 <date>2005-09-07</date>
13
14 <section>
15 <title>Network Modules</title>
16 <body>
17
18 <p>
19 We now support modular networking scripts, which means we can easily add support
20 for new interface types and configuration modules while keeping compatibility
21 with existing ones.
22 </p>
23
24 <p>
25 Modules load by default if the package they need is installed. If you specify a
26 module here that doesn't have its package installed then you get an error
27 stating which package you need to install. Ideally, you only use the modules
28 setting when you have two or more packages installed that supply the same
29 service and you need to prefer one over the other.
30 </p>
31
32 <pre caption="Module preference">
33 <comment># Prefer iproute2 over ifconfig</comment>
34 modules=( "iproute2" )
35
36 <comment># You can also specify other modules for an interface
37 # In this case we prefer udhcpc over dhcpcd</comment>
38 modules_eth0=( "udhcpc" )
39
40 <comment># You can also specify which modules not to use - for example you may be
41 # using a supplicant or linux-wlan-ng to control wireless configuration but
42 # you still want to configure network settings per ESSID associated with.</comment>
43 modules=( "!iwconfig" )
44 </pre>
45
46 </body>
47 </section>
48 <section>
49 <title>Interface Handlers</title>
50 <body>
51
52 <p>
53 We provide two interface handlers presently: ifconfig and iproute2. You need one
54 of these to do any kind of network configuration.
55 </p>
56
57 <p>
58 ifconfig is the current Gentoo default and it's included in the system profile.
59 iproute2 is a more powerful and flexible package, but it's not included by
60 default.
61 </p>
62
63 <pre caption="To install iproute2">
64 # <i>emerge sys-apps/iproute2</i>
65
66 <comment># To prefer iproute2 over ifconfig if both are installed</comment>
67 modules=( "iproute2" )
68 </pre>
69
70 <p>
71 As both ifconfig and iproute2 do very similar things we allow their basic
72 configuration to work with each other. For example both the below code snippets
73 work regardless of which module you are using.
74 </p>
75
76 <pre caption="ifconfig and iproute2 examples">
77 config_eth0=( "192.168.0.2/24" )
78 config_eth0=( "192.168.0.2 netmask 255.255.255.0" )
79
80 <comment># We can also specify broadcast</comment>
81 config_eth0=( "192.168.0.2/24 brd 192.168.0.255" )
82 config_eth0=( "192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255" )
83 </pre>
84
85 </body>
86 </section>
87 <section id="dhcp">
88 <title>DHCP</title>
89 <body>
90
91 <p>
92 DHCP is a means of obtaining network information (IP address, DNS servers,
93 Gateway, etc) from a DHCP server. This means that if there is a DHCP server
94 running on the network, you just have to tell each client to use DHCP and it
95 sets up the network all by itself. Of course, you will have to configure for
96 other things like wireless, ppp or other things if required before you can use
97 DHCP.
98 </p>
99
100 <p>
101 DHCP can be provided by dhclient, dhcpcd, pump or udhcpc. Each DHCP module has
102 its pros and cons - here's a quick run down.
103 </p>
104
105 <table>
106 <tr>
107 <th>DHCP Module</th>
108 <th>Package</th>
109 <th>Pros</th>
110 <th>Cons</th>
111 </tr>
112 <tr>
113 <ti>dhclient</ti>
114 <ti>net-misc/dhcp</ti>
115 <ti>
116 Made by ISC, the same people who make the BIND DNS software. Very
117 configurable
118 </ti>
119 <ti>
120 Configuration is overly complex, software is quite bloated, cannot get
121 NTP servers from DHCP, does not send hostname by default
122 </ti>
123 </tr>
124 <tr>
125 <ti>dhcpcd</ti>
126 <ti>net-misc/dhcpcd</ti>
127 <ti>
128 Long time Gentoo default, no reliance on outside tools
129 </ti>
130 <ti>
131 No longer maintained upstream, can be slow at times, does not daemonize
132 when lease is infinite
133 </ti>
134 </tr>
135 <tr>
136 <ti>pump</ti>
137 <ti>net-misc/pump</ti>
138 <ti>
139 Lightweight, no reliance on outside tools
140 </ti>
141 <ti>
142 No longer maintained upstream, unreliable, especially over modems, cannot
143 get NIS servers from DHCP
144 </ti>
145 </tr>
146 <tr>
147 <ti>udhcpc</ti>
148 <ti>net-misc/udhcp</ti>
149 <ti>
150 Lightweight - smallest dhcp client around, made for embedded systems
151 </ti>
152 <ti>
153 Unproven - no distro uses it by default, cannot define a timeout beyond 3
154 seconds
155 </ti>
156 </tr>
157 </table>
158
159 <p>
160 If you have more than one DHCP client installed, you need to specify which one
161 to use - otherwise we default to dhcpcd if available.
162 </p>
163
164 <p>
165 To send specific options to the dhcp module, use module_eth0="..."
166 <e>(change module to the DHCP module you're using - ie dhcpcd_eth0)</e>
167 </p>
168
169 <p>
170 We try and make DHCP relatively agnostic - as such we support the following
171 commands using the dhcp_eth0 variable. The default is not to set any of them
172 </p>
173
174 <ul>
175 <li>release - releases the IP address for re-use</li>
176 <li>nodns - don't overwrite /etc/resolv.conf</li>
177 <li>nontp - don't overwrite /etc/ntp.conf</li>
178 <li>nonis - don't overwrite /etc/yp.conf</li>
179 </ul>
180
181 <pre caption="Sample DHCP configuration in /etc/conf.d/net">
182 <comment># Only needed if you have more than one DHCP module installed</comment>
183 modules=( "dhcpcd" )
184
185 config_eth0=( "dhcp" )
186 dhcpcd_eth0="-t 10" <comment># Timeout after 10 seconds</comment>
187 dhcp_eth0="release nodns nontp nonis" <comment># Only get an address</comment>
188 </pre>
189
190 <note>
191 dhcpcd, udhcpc and pump send the current hostname to the DHCP server by default
192 so you don't need to specify this anymore.
193 </note>
194
195 </body>
196 </section>
197 <section>
198 <title>ADSL Modem</title>
199 <body>
200
201 <p>
202 First we need to install the ADSL software.
203 </p>
204
205 <pre caption="Install the rp-pppoe package">
206 # <i>emerge net-dialup/rp-pppoe</i>
207 </pre>
208
209 <warn>
210 baselayout-1.11.x supports PPPOE only. Hopefully future versions will support
211 PPPOA.
212 </warn>
213
214 <p>
215 Now we need to instruct configure eth0 to be an ADSL interface and enter our
216 username.
217 </p>
218
219 <pre caption="Configure eth0 for ADSL">
220 config_eth0=( "adsl" )
221 adsl_user_eth0="username"
222 </pre>
223
224 <p>
225 Finally you need to define your username and password in
226 <path>/etc/ppp/pap-secrets</path>
227 </p>
228
229 <pre caption="sample /etc/ppp/pap-secrets">
230 <comment># The * is important</comment>
231 "username" * "password"
232 </pre>
233
234 </body>
235 </section>
236 <section id="apipa">
237 <title>APIPA (Automatic Private IP Addressing)</title>
238 <body>
239
240 <p>
241 APIPA tries to find a free address in the range 169.254.0.0-169.254.255.255 by
242 arping a random address in that range on the interface. If no reply is found
243 then we assign that address to the interface.
244 </p>
245
246 <p>
247 This is only useful for LANs where there is no DHCP server and you don't connect
248 directly to the internet and all other computers use APIPA.
249 </p>
250
251 <p>
252 For APIPA support, emerge net-misc/iputils or net-analyzer/arping
253 </p>
254
255 <pre caption="APIPA configuration in /etc/conf.d/net">
256 <comment># Try DHCP first - if that fails then fallback to APIPA</comment>
257 config_eth0=( "dhcp" )
258 fallback_eth0=( "apipa" )
259
260 <comment># Just use APIPA</comment>
261 config_eth0=( "apipa" )
262 </pre>
263
264 </body>
265 </section>
266 <section>
267 <title>Bonding</title>
268 <body>
269
270 <p>
271 For link bonding/trunking emerge net-misc/ifenslave
272 </p>
273
274 <p>
275 Bonding is used to increase network bandwidth. If you have two network cards
276 going to the same network, you can bond them together so your applications see
277 just one interface but they really use both network cards.
278 </p>
279
280 <pre caption="bonding configuration in /etc/conf.d/net">
281 <comment>To bond interfaces together</comment>
282 slaves_bond0="eth0 eth1 eth2"
283
284 <comment># You may not want to assign an IP to the bonded interface</comment>
285 config_bond0=( "null" )
286
287 <comment># Depend on eth0, eth1 and eth2 as they may require extra configuration</comment>
288 depend_bond0() {
289 need net.eth0 net.eth1 net.eth2
290 }
291 </pre>
292
293 </body>
294 </section>
295 <section>
296 <title>Bridging (802.1d support)</title>
297 <body>
298
299 <p>
300 For bridging support emerge net-misc/bridge-utils
301 </p>
302
303 <p>
304 Bridging is used to join networks together. For example, you may have a server
305 that connects to the internet via an ADSL modem and a wireless access card to
306 enable other computers to connect to the internet via the ADSL modem. You could
307 create a bridge to join the two interfaces together.
308 </p>
309
310 <pre caption="Bridge configuration in /etc/conf.d/net">
311 <comment># Configure the bridge - "man btctl" for more details</comment>
312 brctl_br0=( "setfd 0" "sethello 0" "stp off" )
313
314 <comment># To add ports to bridge br0</comment>
315 bridge_br0="eth0 eth1"
316
317 <comment># You need to configure the ports to null values so dhcp does not get started</comment>
318 config_eth0=( "null" )
319 config_eth1=( "null" )
320
321 <comment># Finally give the bridge an address - you could use DHCP as well</comment>
322 config_br0=( "192.168.0.1/24" )
323
324 <comment># Depend on eth0 and eth1 as they may require extra configuration</comment>
325 depend_br0() {
326 need net.eth0 net.eth1
327 }
328 </pre>
329
330 <impo>
331 For using some bridge setups, you may need to consult the
332 <uri link="?part=4&amp;chap=2#variable_name">variable name</uri>
333 documentation.
334 </impo>
335
336 </body>
337 </section>
338 <section>
339 <title>MAC Address</title>
340 <body>
341
342 <p>
343 You don't need to emerge anything for changing the MAC address of your interface
344 if you change to a specific address. However, if you need to change to a random
345 address or a random address of a given type then you need to emerge
346 net-analyzer/macchanger.
347 </p>
348
349 <pre caption="MAC Address change example">
350 <comment># To set the MAC address of the interface</comment>
351 mac_eth0="00:11:22:33:44:55"
352
353 <comment># To randomize the last 3 bytes only</comment>
354 mac_eth0="random-ending"
355
356 <comment># To randomize between the same physical type of connection (eg fibre,
357 # copper, wireless) , all vendors</comment>
358 mac_eth0="random-samekind"
359
360 <comment># To randomize between any physical type of connection (eg fibre, copper,
361 # wireless) , all vendors</comment>
362 mac_eth0="random-anykind"
363
364 <comment># Full randomization - WARNING: some MAC addresses generated by this may
365 # NOT act as expected</comment>
366 mac_eth0="random-full"
367 </pre>
368
369 </body>
370 </section>
371 <section>
372 <title>Tunnelling</title>
373 <body>
374
375 <p>
376 You don't need to emerge anything for tunnelling as the interface handler can do
377 it for you.
378 </p>
379
380 <pre caption="Tunnelling configuration in /etc/conf.d/net">
381 <comment># For GRE tunnels</comment>
382 iptunnel_vpn0="mode gre remote 207.170.82.1 key 0xffffffff ttl 255"
383
384 <comment># For IPIP tunnels</comment>
385 iptunnel_vpn0="mode ipip remote 207.170.82.2 ttl 255"
386
387 <comment># To configure the interface</comment>
388 config_vpn0=( "192.168.0.2 peer 192.168.1.1" )
389 </pre>
390
391 </body>
392 </section>
393 <section>
394 <title>VLAN (802.1q support)</title>
395 <body>
396
397 <p>
398 For VLAN support, emerge net-misc/vconfig
399 </p>
400
401 <p>
402 Virtual LAN is a group of network devices that behave as if they were connected
403 to a single network segment - even though they may not be. VLAN members can only
404 see members of the same VLAN even though they may share the same physical
405 network.
406 </p>
407
408 <pre caption="VLAN configuration in /etc/conf.d/net">
409 <comment># Specify the VLAN numbers for the interface like so</comment>
410 <comment># Please ensure your VLAN IDs are NOT zero-padded</comment>
411 vlans_eth0="1 2"
412
413 <comment># You can also configure the VLAN</comment>
414 <comment># see for vconfig man page for more details</comment>
415 vconfig_eth0=( "set_name_type VLAN_PLUS_VID_NO_PAD" )
416 vconfig_vlan1=( "set_flag 1" "set_egress_map 2 6" )
417
418 <comment># Configure the interface as usual</comment>
419 config_vlan1=( "172.16.3.1 netmask 255.255.254.0" )
420 config_vlan2=( "172.16.2.1 netmask 255.255.254.0" )
421 </pre>
422
423 <impo>
424 For using some VLAN setups, you may need to consult the
425 <uri link="?part=4&amp;chap=2#variable_name">variable name</uri>
426 documentation.
427 </impo>
428
429 </body>
430 </section>
431
432 </sections>

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