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Revision 1.25 - (show annotations) (download) (as text)
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remove references to udhcp. per flameeyes' last rites email to gentoo-dev on 12-23-2008, udhcp has been superceded by busybox.

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 1.24 2007/11/02 20:33:55 nightmorph Exp $ -->
8
9 <sections>
10
11 <abstract>
12 Gentoo provides you flexible networking - here you are told about choosing
13 different DHCP clients, setting up bonding, bridging, VLANs and more.
14 </abstract>
15
16 <version>8.4</version>
17 <date>2009-02-12</date>
18
19 <section>
20 <title>Network Modules</title>
21 <body>
22
23 <p>
24 We now support modular networking scripts, which means we can easily add support
25 for new interface types and configuration modules while keeping compatibility
26 with existing ones.
27 </p>
28
29 <p>
30 Modules load by default if the package they need is installed. If you specify a
31 module here that doesn't have its package installed then you get an error
32 stating which package you need to install. Ideally, you only use the modules
33 setting when you have two or more packages installed that supply the same
34 service and you need to prefer one over the other.
35 </p>
36
37 <note>
38 All settings discussed here are stored in <path>/etc/conf.d/net</path> unless
39 otherwise specified.
40 </note>
41
42 <pre caption="Module preference">
43 <comment># Prefer iproute2 over ifconfig</comment>
44 modules=( "iproute2" )
45
46 <comment># You can also specify other modules for an interface
47 # In this case we prefer pump over dhcpcd</comment>
48 modules_eth0=( "pump" )
49
50 <comment># You can also specify which modules not to use - for example you may be
51 # using a supplicant or linux-wlan-ng to control wireless configuration but
52 # you still want to configure network settings per ESSID associated with.</comment>
53 modules=( "!iwconfig" )
54 </pre>
55
56 </body>
57 </section>
58 <section>
59 <title>Interface Handlers</title>
60 <body>
61
62 <p>
63 We provide two interface handlers presently: <c>ifconfig</c> and
64 <c>iproute2</c>. You need one of these to do any kind of network configuration.
65 </p>
66
67 <p>
68 <c>ifconfig</c> is the current Gentoo default and it's included in the system
69 profile. <c>iproute2</c> is a more powerful and flexible package, but it's not
70 included by default.
71 </p>
72
73 <pre caption="To install iproute2">
74 # <i>emerge sys-apps/iproute2</i>
75
76 <comment># To prefer iproute2 over ifconfig if both are installed</comment>
77 modules=( "iproute2" )
78 </pre>
79
80 <p>
81 As both <c>ifconfig</c> and <c>iproute2</c> do very similar things we allow
82 their basic configuration to work with each other. For example both the below
83 code snippet work regardless of which module you are using.
84 </p>
85
86 <pre caption="ifconfig and iproute2 examples">
87 config_eth0=( "192.168.0.2/24" )
88 config_eth0=( "192.168.0.2 netmask 255.255.255.0" )
89
90 <comment># We can also specify broadcast</comment>
91 config_eth0=( "192.168.0.2/24 brd 192.168.0.255" )
92 config_eth0=( "192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255" )
93 </pre>
94
95 </body>
96 </section>
97 <section id="dhcp">
98 <title>DHCP</title>
99 <body>
100
101 <p>
102 DHCP is a means of obtaining network information (IP address, DNS servers,
103 Gateway, etc) from a DHCP server. This means that if there is a DHCP server
104 running on the network, you just have to tell each client to use DHCP and it
105 sets up the network all by itself. Of course, you will have to configure for
106 other things like wireless, PPP or other things if required before you can use
107 DHCP.
108 </p>
109
110 <p>
111 DHCP can be provided by <c>dhclient</c>, <c>dhcpcd</c>, or <c>pump</c>. Each
112 DHCP module has its pros and cons - here's a quick run down.
113 </p>
114
115 <table>
116 <tr>
117 <th>DHCP Module</th>
118 <th>Package</th>
119 <th>Pros</th>
120 <th>Cons</th>
121 </tr>
122 <tr>
123 <ti><c>dhclient</c></ti>
124 <ti><c>net-misc/dhcp</c></ti>
125 <ti>
126 Made by ISC, the same people who make the BIND DNS software. Very
127 configurable
128 </ti>
129 <ti>
130 Configuration is overly complex, software is quite bloated, cannot get
131 NTP servers from DHCP, does not send hostname by default
132 </ti>
133 </tr>
134 <tr>
135 <ti><c>dhcpcd</c></ti>
136 <ti><c>net-misc/dhcpcd</c></ti>
137 <ti>
138 Long time Gentoo default, no reliance on outside tools, actively developed
139 by Gentoo
140 </ti>
141 <ti>Can be slow at times, does not yet daemonize when lease is infinite</ti>
142 </tr>
143 <tr>
144 <ti><c>pump</c></ti>
145 <ti><c>net-misc/pump</c></ti>
146 <ti>
147 Lightweight, no reliance on outside tools
148 </ti>
149 <ti>
150 No longer maintained upstream, unreliable, especially over modems, cannot
151 get NIS servers from DHCP
152 </ti>
153 </tr>
154 </table>
155
156 <p>
157 If you have more than one DHCP client installed, you need to specify which one
158 to use - otherwise we default to <c>dhcpcd</c> if available.
159 </p>
160
161 <p>
162 To send specific options to the DHCP module, use <c>module_eth0="..."</c>
163 <e>(change module to the DHCP module you're using - i.e. <c>dhcpcd_eth0</c>)</e>.
164 </p>
165
166 <p>
167 We try and make DHCP relatively agnostic - as such we support the following
168 commands using the <c>dhcp_eth0</c> variable. The default is not to set any of
169 them:
170 </p>
171
172 <ul>
173 <li><c>release</c> - releases the IP address for re-use</li>
174 <li><c>nodns</c> - don't overwrite <path>/etc/resolv.conf</path></li>
175 <li><c>nontp</c> - don't overwrite <path>/etc/ntp.conf</path></li>
176 <li><c>nonis</c> - don't overwrite <path>/etc/yp.conf</path></li>
177 </ul>
178
179 <pre caption="Sample DHCP configuration in /etc/conf.d/net">
180 <comment># Only needed if you have more than one DHCP module installed</comment>
181 modules=( "dhcpcd" )
182
183 config_eth0=( "dhcp" )
184 dhcpcd_eth0="-t 10" <comment># Timeout after 10 seconds</comment>
185 dhcp_eth0="release nodns nontp nonis" <comment># Only get an address</comment>
186 </pre>
187
188 <note>
189 <c>dhcpcd</c> and <c>pump</c> send the current hostname to the
190 DHCP server by default so you don't need to specify this anymore.
191 </note>
192
193 </body>
194 </section>
195 <section>
196 <title>ADSL with PPPoE/PPPoA</title>
197 <body>
198
199 <p>
200 First we need to install the ADSL software.
201 </p>
202
203 <pre caption="Install the ppp package">
204 # <i>emerge net-dialup/ppp</i>
205 </pre>
206
207 <note>
208 If you need PPPoA, then make sure to use >=<c>baselayout-1.12.x</c>.
209 </note>
210
211 <p>
212 Second, create the PPP net script and the net script for the ethernet interface
213 to be used by PPP:
214 </p>
215
216 <pre caption="Creating the PPP and ethernet scripts">
217 # <i>ln -s /etc/init.d/net.lo /etc/init.d/net.ppp0</i>
218 # <i>ln -s /etc/init.d/net.lo /etc/init.d/net.eth0</i>
219 </pre>
220
221 <p>
222 Be sure to set RC_NET_STRICT_CHECKING="yes" in <path>/etc/conf.d/rc</path>.
223 </p>
224
225 <p>
226 Now we need to configure <path>/etc/conf.d/net</path>.
227 </p>
228
229 <pre caption="A basic PPPoE setup">
230 config_eth0=( null ) <comment>(Specify your ethernet interface)</comment>
231 config_ppp0=( "ppp" )
232 link_ppp0="eth0" <comment>(Specify your ethernet interface)</comment>
233 plugins_ppp0=( "pppoe" )
234 username_ppp0='user'
235 password_ppp0='password'
236 pppd_ppp0=(
237 "noauth"
238 "defaultroute"
239 "usepeerdns"
240 "holdoff 3"
241 "child-timeout 60"
242 "lcp-echo-interval 15"
243 "lcp-echo-failure 3"
244 noaccomp noccp nobsdcomp nodeflate nopcomp novj novjccomp
245 )
246
247 depend_ppp0() {
248 need net.eth0
249 }
250 </pre>
251
252 <p>
253 You can also set your password in <path>/etc/ppp/pap-secrets</path>.
254 </p>
255
256 <pre caption="Sample /etc/ppp/pap-secrets">
257 <comment># The * is important</comment>
258 "username" * "password"
259 </pre>
260
261 <p>
262 If you use PPPoE with a USB modem you'll need to emerge <c>br2684ctl</c>. Please
263 read <path>/usr/portage/net-dialup/speedtouch-usb/files/README</path> for
264 information on how to properly configure it.
265 </p>
266
267 <impo>
268 Please carefully read the section on ADSL and PPP in
269 <path>/etc/conf.d/net.example</path>. It contains many more detailed
270 explanations of all the settings your particular PPP setup will likely need.
271 </impo>
272
273 </body>
274 </section>
275 <section id="apipa">
276 <title>APIPA (Automatic Private IP Addressing)</title>
277 <body>
278
279 <p>
280 APIPA tries to find a free address in the range 169.254.0.0-169.254.255.255 by
281 arping a random address in that range on the interface. If no reply is found
282 then we assign that address to the interface.
283 </p>
284
285 <p>
286 This is only useful for LANs where there is no DHCP server and you don't connect
287 directly to the internet and all other computers use APIPA.
288 </p>
289
290 <p>
291 For APIPA support, emerge <c>net-misc/iputils</c> or <c>net-analyzer/arping</c>.
292 </p>
293
294 <pre caption="APIPA configuration in /etc/conf.d/net">
295 <comment># Try DHCP first - if that fails then fallback to APIPA</comment>
296 config_eth0=( "dhcp" )
297 fallback_eth0=( "apipa" )
298
299 <comment># Just use APIPA</comment>
300 config_eth0=( "apipa" )
301 </pre>
302
303 </body>
304 </section>
305 <section>
306 <title>Bonding</title>
307 <body>
308
309 <p>
310 For link bonding/trunking emerge <c>net-misc/ifenslave</c>.
311 </p>
312
313 <p>
314 Bonding is used to increase network bandwidth. If you have two network cards
315 going to the same network, you can bond them together so your applications see
316 just one interface but they really use both network cards.
317 </p>
318
319 <pre caption="bonding configuration in /etc/conf.d/net">
320 <comment># To bond interfaces together</comment>
321 slaves_bond0="eth0 eth1 eth2"
322
323 <comment># You may not want to assign an IP to the bonded interface</comment>
324 config_bond0=( "null" )
325
326 <comment># Depend on eth0, eth1 and eth2 as they may require extra configuration</comment>
327 depend_bond0() {
328 need net.eth0 net.eth1 net.eth2
329 }
330 </pre>
331
332 </body>
333 </section>
334 <section>
335 <title>Bridging (802.1d support)</title>
336 <body>
337
338 <p>
339 For bridging support emerge <c>net-misc/bridge-utils</c>.
340 </p>
341
342 <p>
343 Bridging is used to join networks together. For example, you may have a server
344 that connects to the internet via an ADSL modem and a wireless access card to
345 enable other computers to connect to the internet via the ADSL modem. You could
346 create a bridge to join the two interfaces together.
347 </p>
348
349 <pre caption="Bridge configuration in /etc/conf.d/net">
350 <comment># Configure the bridge - "man brctl" for more details</comment>
351 brctl_br0=( "setfd 0" "sethello 0" "stp off" )
352
353 <comment># To add ports to bridge br0</comment>
354 bridge_br0="eth0 eth1"
355
356 <comment># You need to configure the ports to null values so dhcp does not get started</comment>
357 config_eth0=( "null" )
358 config_eth1=( "null" )
359
360 <comment># Finally give the bridge an address - you could use DHCP as well</comment>
361 config_br0=( "192.168.0.1/24" )
362
363 <comment># Depend on eth0 and eth1 as they may require extra configuration</comment>
364 depend_br0() {
365 need net.eth0 net.eth1
366 }
367 </pre>
368
369 <impo>
370 For using some bridge setups, you may need to consult the <uri
371 link="?part=4&amp;chap=2#variable_name">variable name</uri> documentation.
372 </impo>
373
374 </body>
375 </section>
376 <section>
377 <title>MAC Address</title>
378 <body>
379
380 <p>
381 You don't need to emerge anything for changing the MAC address of your
382 interface if you have <c>sys-apps/baselayout-1.11.14</c> or newer and want to
383 change to a specific MAC address. However, if you need to change to a random MAC
384 address or have a baselayout older than the version mentioned above, you have
385 to emerge <c>net-analyzer/macchanger</c> to be able to make use of this feature.
386 </p>
387
388 <pre caption="MAC Address change example">
389 <comment># To set the MAC address of the interface</comment>
390 mac_eth0="00:11:22:33:44:55"
391
392 <comment># To randomize the last 3 bytes only</comment>
393 mac_eth0="random-ending"
394
395 <comment># To randomize between the same physical type of connection (e.g. fibre,
396 # copper, wireless) , all vendors</comment>
397 mac_eth0="random-samekind"
398
399 <comment># To randomize between any physical type of connection (e.g. fibre, copper,
400 # wireless) , all vendors</comment>
401 mac_eth0="random-anykind"
402
403 <comment># Full randomization - WARNING: some MAC addresses generated by this may
404 # NOT act as expected</comment>
405 mac_eth0="random-full"
406 </pre>
407
408 </body>
409 </section>
410 <section>
411 <title>Tunnelling</title>
412 <body>
413
414 <p>
415 You don't need to emerge anything for tunnelling as the interface handler can do
416 it for you.
417 </p>
418
419 <pre caption="Tunnelling configuration in /etc/conf.d/net">
420 <comment># For GRE tunnels</comment>
421 iptunnel_vpn0="mode gre remote 207.170.82.1 key 0xffffffff ttl 255"
422
423 <comment># For IPIP tunnels</comment>
424 iptunnel_vpn0="mode ipip remote 207.170.82.2 ttl 255"
425
426 <comment># To configure the interface</comment>
427 config_vpn0=( "192.168.0.2 peer 192.168.1.1" )
428 </pre>
429
430 </body>
431 </section>
432 <section>
433 <title>VLAN (802.1q support)</title>
434 <body>
435
436 <p>
437 For VLAN support, emerge <c>net-misc/vconfig</c>.
438 </p>
439
440 <p>
441 Virtual LAN is a group of network devices that behave as if they were connected
442 to a single network segment - even though they may not be. VLAN members can only
443 see members of the same VLAN even though they may share the same physical
444 network.
445 </p>
446
447 <pre caption="VLAN configuration in /etc/conf.d/net">
448 <comment># Specify the VLAN numbers for the interface like so</comment>
449 <comment># Please ensure your VLAN IDs are NOT zero-padded</comment>
450 vlans_eth0="1 2"
451
452 <comment># You can also configure the VLAN</comment>
453 <comment># see for vconfig man page for more details</comment>
454 vconfig_eth0=( "set_name_type VLAN_PLUS_VID_NO_PAD" )
455 vconfig_vlan1=( "set_flag 1" "set_egress_map 2 6" )
456
457 <comment># Configure the interface as usual</comment>
458 config_vlan1=( "172.16.3.1 netmask 255.255.254.0" )
459 config_vlan2=( "172.16.2.1 netmask 255.255.254.0" )
460 </pre>
461
462 <impo>
463 For using some VLAN setups, you may need to consult the <uri
464 link="?part=4&amp;chap=2#variable_name">variable name</uri> documentation.
465 </impo>
466
467 </body>
468 </section>
469
470 </sections>

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