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1 <?xml version='1.0' encoding='UTF-8'?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.66 2013/04/03 18:32:25 vapier Exp $ -->
4
5 <guide disclaimer="obsolete" redirect="https://wiki.gentoo.org/wiki/Home_Router">
6 <title>Home Router Guide</title>
7
8 <author title="Author">
9 <mail link="vapier@gentoo.org">Mike Frysinger</mail>
10 </author>
11
12 <abstract>
13 This document details how to turn an old Gentoo machine into a router
14 for connecting your home network to the internet.
15 </abstract>
16
17 <!-- The content of this document is released into the public domain -->
18 <license/>
19
20 <version>3</version>
21 <date>2013-04-03</date>
22
23 <chapter>
24 <title>Introduction</title>
25 <section>
26 <body>
27
28 <p>
29 Building your own router out of old spare parts has many advantages over buying
30 a pre-made canned router by say Linksys. The biggest one by far is control
31 over the connection. The other advantages are left up to your imagination;
32 just about anything can be done in this scenario, it's just a matter of needing
33 it.
34 </p>
35
36 <p>
37 This guide will show you how to setup Network Address Translation (NAT) on the
38 router (kernel and iptables), add and configure common services (Domain Name
39 System (DNS) via dnsmasq, dhcp via dhcpcd, ADSL via ppp), and conclude
40 with more elaborate and fun things that can be done (port forwarding, traffic
41 shaping, proxies/caching, etc...).
42 </p>
43
44 <p>
45 Before getting started, there's a few basic requirements you must meet. First,
46 you'll need a computer that has at least 2 Network Interface Cards (NICs) in
47 it. Next, you'll need the configuration settings for your internet connection
48 (may include things like IP/DNS/Gateway/username/password). Finally, you'll
49 need a bit of spare time and some Gentoo loving.
50 </p>
51
52 <p>
53 The conventions used in this guide are:
54 </p>
55
56 <ul>
57 <li>eth0 - NIC connected to the Local Area Network (LAN)</li>
58 <li>eth1 - NIC connected to the Wide Area Network (WAN)</li>
59 <li>LAN utilizes the private 192.168.0.xxx network</li>
60 <li>router is hardcoded to the standard 192.168.0.1 IP</li>
61 <li>router is running Linux 2.4 or 2.6; you're on your own with 2.0/2.2</li>
62 </ul>
63
64 <impo>
65 Due to security precautions, I would highly suggest you shut down any unneeded
66 services on the router until we have a chance to get the firewall up and
67 rolling. To view the currently running services, just run <c>rc-status</c>.
68 </impo>
69
70 </body>
71 </section>
72 </chapter>
73
74 <chapter>
75 <title>Kernel setup (know thyself first)</title>
76 <section>
77 <body>
78
79 <p>
80 Your kernel needs to have the drivers running for both your NICs. To see if
81 your cards are already setup, just run <c>ifconfig</c>. Your output may differ
82 slightly from the following, that's fine. What matters is that the interface
83 shows up at all.
84 </p>
85
86 <pre caption="Checking NICs">
87 # <i>ifconfig -a</i>
88 eth0 Link encap:Ethernet HWaddr 00:60:F5:07:07:B8
89 BROADCAST MULTICAST MTU:1500 Metric:1
90 RX packets:0 errors:0 dropped:0 overruns:0 frame:0
91 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
92 collisions:0 txqueuelen:1000
93 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
94 Interrupt:11 Base address:0x9800
95
96 eth1 Link encap:Ethernet HWaddr 00:60:F5:07:07:B9
97 BROADCAST MULTICAST MTU:1500 Metric:1
98 RX packets:0 errors:0 dropped:0 overruns:0 frame:0
99 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
100 collisions:0 txqueuelen:1000
101 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
102 Interrupt:10 Base address:0x9400
103 </pre>
104
105 <p>
106 If you do not see your two cards showing up and you're not sure what kind of
107 cards you have, try running <c>lspci | grep Ethernet</c>. You can get that
108 from <c>emerge pciutils</c>. Once you have this information, go into your
109 kernel and add support for the correct drivers.
110 </p>
111
112 <p>
113 The next thing you'll need is support for iptables and NAT (and packet shaping
114 if you want). The following list is split up into always required (*),
115 required only for adsl via PPPoE (a), suggested for everyone (x), and only
116 for shaper (s) features. It does not matter whether you build the features
117 into the kernel or as a module so long as when the feature is needed, the
118 correct module(s) are loaded (module loading is left to the reader as a fun
119 exercise however).
120 </p>
121
122 <pre caption="Network Options">
123 Networking options ---&gt;
124 [*] TCP/IP networking
125 [*] IP: advanced router
126 [*] Network packet filtering (replaces ipchains)
127 <comment>If you use 2.4.x, you have to enable the following for DHCP:</comment>
128 [*] Socket Filtering
129
130 IP: Netfilter Configuration ---&gt;
131 [*] Connection tracking (required for masq/NAT)
132 [x] FTP protocol support
133 [x] IRC protocol support
134 [*] IP tables support (required for filtering/masq/NAT)
135 [*] IP range match support
136 [x] MAC address match support
137 [*] Multiple port match support
138 [*] Packet filtering
139 [*] REJECT target support
140 [x] REDIRECT target support
141 [*] Full NAT
142 [*] MASQUERADE target support
143 [s] Packet mangling
144 [s] MARK target support
145 [x] LOG target support
146
147 QoS and/or fair queueing ---&gt;
148 [s] QoS and/or fair queueing
149 [s] HTB packet scheduler
150 [s] Ingress Qdisc
151
152 [a] PPP (point-to-point protocol) support
153 [a] PPP filtering
154 [a] PPP support for async serial ports
155 [a] PPP support for sync tty ports
156 [a] PPP Deflate compression
157 [a] PPP BSD-Compress compression
158 [a] PPP over Ethernet
159 </pre>
160
161 <note>
162 Some things may be slightly different in a 2.4 vs 2.6 kernel, but you should be
163 able to figure it out :). Even among 2.6 kernels, these options have a
164 tendency to move around. Good luck!
165 </note>
166
167 </body>
168 </section>
169 </chapter>
170
171 <chapter>
172 <title>Hug the WAN (a.k.a. The Internet)</title>
173
174 <section>
175 <title>Intro</title>
176 <body>
177
178 <p>
179 There are many ways to connect to the internet so I'll just cover the ones I'm
180 familiar with. That leaves us with ADSL (PPPoE) and cable modems
181 (static/dynamic). If there are other methods out there, feel free to write up
182 a little blurb and e-mail me. Feel free to skip any of the following sections
183 in this chapter that don't apply to you. This chapter is just about getting
184 the router connected to the internet via eth1.
185 </p>
186
187 </body>
188 </section>
189 <section>
190 <title>ADSL and PPPoE</title>
191 <body>
192
193 <p>
194 All the fancy PPPoE software that used to be provided by rp-pppoe
195 (<uri link="http://www.roaringpenguin.com/">Roaring Penguin</uri>) has been
196 integrated into the <uri link="http://samba.org/ppp/">standard PPP
197 package</uri>. Simply <c>emerge ppp</c> and you'll be on your way. Remember
198 how I said you'll need username/password information? Well I wasn't lying so
199 I hope you have it now! Load up <path>/etc/conf.d/net</path> in your favorite
200 editor and set it up.
201 </p>
202
203 <pre caption="Setting up eth1">
204 <comment>(Replace 'vla9h924' with your username and 'boogie' with your password)</comment>
205
206 # <i>nano /etc/conf.d/net</i>
207 <comment>Tell openrc to use adsl over eth1 for ppp0:</comment>
208 config_ppp0="ppp"
209 link_ppp0="eth1"
210 plugins_ppp0="pppoe"
211 pppd_ppp0="
212 defaultroute
213 usepeerdns
214 <comment>There may be other settings you want, see /usr/share/doc/openrc-*/net.example.bz2</comment>
215 "
216 username_ppp0="vla9h924"
217 password_ppp0="boogie"
218
219 # <i>ln -s net.lo /etc/init.d/net.ppp0</i>
220 # <i>rc-update add net.ppp0 default</i>
221 # <i>/etc/init.d/net.ppp0 start</i>
222 </pre>
223
224 <warn>
225 When the DSL interface comes up, it will create ppp0. Although your NIC is
226 called eth1, the IP is actually bound to ppp0. From now on, when you see
227 examples that utilize 'eth1', substitute with 'ppp0'.
228 </warn>
229
230 <warn>
231 Make sure you change the permissions of the /etc/conf.d/net file so that only
232 root can read/write it since you're sticking your username/password in it.
233 </warn>
234
235 <warn>
236 For people transitioning from the <c>rp-pppoe</c> package, or for people who
237 hit weird connection resets, see the MTU section in the Troubleshooting
238 chapter.
239 </warn>
240
241 </body>
242 </section>
243
244 <section>
245 <title>Cable and/or dynamic/static IP</title>
246 <body>
247
248 <p>
249 If you have a static IP then you will need a few more details than if
250 you have a dynamic IP. For static users, you will need your IP,
251 gateway, and DNS servers.
252 </p>
253
254 <pre caption="Setting up eth1">
255 <comment>Dynamic IP Users:</comment>
256 # <i>emerge dhcpcd</i>
257 # <i>nano /etc/conf.d/net</i>
258 <comment>You'll need an entry like so:</comment>
259 config_eth1="dhcp"
260
261 <comment>Static IP Users:</comment>
262 # <i>nano /etc/conf.d/net</i>
263 <comment>You'll need entries like so:</comment>
264 config_eth1="66.92.78.102/24 brd 66.92.78.255"
265 routes_eth1="default via 66.92.78.1"
266 # <i>nano /etc/resolv.conf</i>
267 <comment>Add one line per DNS server:</comment>
268 nameserver 123.123.123.123
269
270 <comment>Dynamic and Static Setup:</comment>
271 # <i>ln -s net.lo /etc/init.d/net.eth1</i>
272 # <i>rc-update add net.eth1 default</i>
273 # <i>/etc/init.d/net.eth1 start</i>
274 </pre>
275
276 <p>
277 You should be all set to go now.
278 </p>
279
280 </body>
281 </section>
282 </chapter>
283
284 <chapter>
285 <title>Hug the LAN (bring along some friends)</title>
286 <section>
287 <body>
288
289 <p>
290 This step is a breeze compared to the previous one.
291 </p>
292
293 <pre caption="Setting up eth0">
294 # <i>nano /etc/conf.d/net</i>
295 <comment>Add a line like the following:</comment>
296 config_eth0="192.168.0.1/24 brd 192.168.0.255"
297 # <i>rc-update add net.eth0 default</i>
298 # <i>/etc/init.d/net.eth0 start</i>
299 </pre>
300
301 </body>
302 </section>
303 </chapter>
304
305 <chapter>
306 <title>LAN Services (because we're nice people)</title>
307
308 <section>
309 <title>DHCP Server</title>
310 <body>
311
312 <p>
313 I bet it'd be nice if everyone else in your house could just plug their
314 computers into the network and things would just work. No need to remember
315 mind-numbing details or make them stare at confusing configuration screens!
316 Life would be grand eh? Introducing the Dynamic Host Configuration Protocol
317 (DHCP) and why you should care.
318 </p>
319
320 <p>
321 DHCP is exactly what its name implies. It's a protocol that allows you
322 to dynamically configure other hosts automatically. You run a DHCP server on
323 the router, give it all the information about your network (valid IPs,
324 DNS servers, gateways, etc...), and then when the other hosts start up, they
325 run a DHCP client to automatically configure themselves. No fuss, no muss!
326 For more information about DHCP, you can always visit <uri
327 link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
328 </p>
329
330 <p>
331 We'll use a package called dnsmasq which provides both DHCP and DNS services.
332 For now lets just focus on the DHCP aspect. Note that if you want to run a
333 different DHCP server, you can find another example in the Fun Things chapter.
334 Also, if you wish to tinker with the DHCP server settings, just read the
335 comments in <path>/etc/dnsmasq.conf</path>. All the defaults should work fine
336 though.
337 </p>
338
339 <pre caption="Setting up a DHCP server">
340 # <i>emerge dnsmasq</i>
341 # <i>nano /etc/dnsmasq.conf</i>
342 <comment>Add this line to enable dhcp:</comment>
343 dhcp-range=192.168.0.100,192.168.0.250,72h
344 <comment>Restrict dnsmasq to just the LAN interface</comment>
345 interface=eth0
346
347 # <i>rc-update add dnsmasq default</i>
348 # <i>/etc/init.d/dnsmasq start</i>
349 </pre>
350
351 <p>
352 Now your little router is a bona-fide DHCP server! Plugin those computers and
353 watch them work! With Windows systems you should go into the TCP/IP Properties
354 and select the 'Obtain an IP address automatically' and 'Obtain DNS server
355 address automatically' options. Sometimes the changes aren't instantaneous, so
356 you may have to open a command prompt and run <c>ipconfig /release</c> and
357 <c>ipconfig /renew</c>. But enough about Windows, let's get back to our
358 favorite penguin.
359 </p>
360
361 </body>
362 </section>
363
364 <section>
365 <title>DNS Server</title>
366 <body>
367
368 <p>
369 When people want to visit a place on the internet, they remember names, not a
370 string of funky numbers. After all, what's easier to remember, ebay.com or
371 66.135.192.87? This is where the DNS steps in. DNS servers run all over the
372 internet, and whenever someone wants to visit 'ebay.com', these servers turn
373 'ebay.com' (what we understand) into '66.135.192.87' (what our computers
374 understand). For more information about DNS, you can always visit <uri
375 link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
376 </p>
377
378 <p>
379 Since we're using dnsmasq for our DHCP server, and it includes a DNS server,
380 you've got nothing left to do here! Your little router is already providing
381 DNS to its DHCP clients. Bet you wish everything was this easy ;).
382 </p>
383
384 <p>
385 You're welcome to choose other DNS servers if you're more comfortable with
386 them, but the reason dnsmasq is great is because it was designed to do exactly
387 what we want and nothing more. It's a little DNS caching/forwarding server for
388 local networks. We're not looking to provide DNS for our own domain here, just
389 offer simple DNS services to everyone else on our LAN.
390 </p>
391
392 </body>
393 </section>
394
395 <section>
396 <title>NAT (a.k.a. IP-masquerading)</title>
397 <body>
398
399 <p>
400 At this point, people on your network can talk to each other and they can look
401 up hostnames via DNS, but they still can't actually connect to the internet.
402 While you may think that's great (more bandwidth for you!), I bet they're not
403 too happy just yet.
404 </p>
405
406 <p>
407 This is where Network Address Translation (NAT) steps in. NAT is a way of
408 connecting multiple computers in a private LAN to the internet when you have a
409 smaller number of public IP addresses available to you. Typically you are given
410 1 IP by your ISP, but you want to let your whole house connect to the internet.
411 NAT is the magic that makes this possible. For more information about NAT, you
412 can always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
413 </p>
414
415 <note>
416 Before we get started, make sure you have iptables on your system. Although it
417 is automatically installed on most systems, you may not have it. If you don't,
418 just run <c>emerge iptables</c>.
419 </note>
420
421 <pre caption="Setting up iptables">
422 <comment>First we flush our current rules</comment>
423 # <i>iptables -F</i>
424 # <i>iptables -t nat -F</i>
425
426 <comment>Setup default policies to handle unmatched traffic</comment>
427 # <i>iptables -P INPUT ACCEPT</i>
428 # <i>iptables -P OUTPUT ACCEPT</i>
429 # <i>iptables -P FORWARD DROP</i>
430
431 <comment>Copy and paste these examples ...</comment>
432 # <i>export LAN=eth0</i>
433 # <i>export WAN=eth1</i>
434
435 <comment>Then we lock our services so they only work from the LAN</comment>
436 # <i>iptables -I INPUT 1 -i ${LAN} -j ACCEPT</i>
437 # <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
438 # <i>iptables -A INPUT -p UDP --dport bootps ! -i ${LAN} -j REJECT</i>
439 # <i>iptables -A INPUT -p UDP --dport domain ! -i ${LAN} -j REJECT</i>
440
441 <comment>(Optional) Allow access to our ssh server from the WAN</comment>
442 # <i>iptables -A INPUT -p TCP --dport ssh -i ${WAN} -j ACCEPT</i>
443
444 <comment>Drop TCP / UDP packets to privileged ports</comment>
445 # <i>iptables -A INPUT -p TCP ! -i ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
446 # <i>iptables -A INPUT -p UDP ! -i ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
447
448 <comment>Finally we add the rules for NAT</comment>
449 # <i>iptables -I FORWARD -i ${LAN} -d 192.168.0.0/255.255.0.0 -j DROP</i>
450 # <i>iptables -A FORWARD -i ${LAN} -s 192.168.0.0/255.255.0.0 -j ACCEPT</i>
451 # <i>iptables -A FORWARD -i ${WAN} -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
452 # <i>iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE</i>
453 <comment>Tell the kernel that ip forwarding is OK</comment>
454 # <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i>
455 # <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
456
457 <comment>This is so when we boot we don't have to run the rules by hand</comment>
458 # <i>/etc/init.d/iptables save</i>
459 # <i>rc-update add iptables default</i>
460 # <i>nano /etc/sysctl.conf</i>
461 <comment>Add/Uncomment the following lines:</comment>
462 net.ipv4.ip_forward = 1
463 net.ipv4.conf.default.rp_filter = 1
464
465 <comment>If you have a dynamic internet address you probably want to enable this:</comment>
466 net.ipv4.ip_dynaddr = 1
467 </pre>
468
469 <p>
470 Once you've typed out all of that, the rest of your network should now be able
471 to use the internet as if they were directly connected themselves.
472 </p>
473
474 <p>
475 The ip_dynaddr option is useful for dial on demand systems or when your ISP
476 gives out dynamic addresses. This works around the problem where a connection
477 is attempted before the internet interface is fully setup. Really this just
478 provides for a smoother network experience for users behind your router.
479 </p>
480
481 </body>
482 </section>
483 </chapter>
484
485 <chapter>
486 <title>Fun Things (for a rainy day)</title>
487
488 <section>
489 <title>Intro</title>
490 <body>
491
492 <p>
493 Believe it or not, you're done :). From here on out, I'll cover a bunch of
494 common topics that may interest you. Everything in this chapter is completely
495 optional.
496 </p>
497
498 </body>
499 </section>
500
501 <section>
502 <title>Port Forwarding</title>
503 <body>
504
505 <p>
506 Sometimes you would like to be able to host services on a computer behind the
507 router, or just to make your life easier when connecting remotely. Perhaps you
508 want to run a FTP, HTTP, SSH, or VNC server on one or more machines behind your
509 router and be able to connect to them all. The only caveat is that you can
510 only have one service/machine combo per port. For example, there is no
511 practical way to setup three FTP servers behind your router and then try to
512 connect to them all through port 21; only one can be on port 21 while the
513 others would have to be on say port 123 and port 567.
514 </p>
515
516 <p>
517 All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING
518 [-p protocol] --dport [external port on router] -i ${WAN} -j DNAT --to [ip/port
519 to forward to]</c>. Unfortunately, iptables does not accept hostnames when port
520 forwarding. If you are forwarding an external port to the same port on the
521 internal machine, you can omit the destination port. See the iptables(8) man
522 page for more information.
523 </p>
524
525 <pre caption="Running the iptables commands">
526 <comment>Copy and paste these examples ...</comment>
527 # <i>export LAN=eth0</i>
528 # <i>export WAN=eth1</i>
529
530 <comment>Forward port 2 to ssh on an internal host</comment>
531 # <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i ${WAN} -j DNAT --to 192.168.0.2:22</i>
532
533 <comment>FTP forwarding to an internal host</comment>
534 # <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i ${WAN} -j DNAT --to 192.168.0.56</i>
535
536 <comment>HTTP forwarding to an internal host</comment>
537 # <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i ${WAN} -j DNAT --to 192.168.0.56</i>
538
539 <comment>VNC forwarding for internal hosts</comment>
540 # <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i ${WAN} -j DNAT --to 192.168.0.2</i>
541 # <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i ${WAN} -j DNAT --to 192.168.0.3:5900</i>
542 <comment>If you want to VNC in to 192.168.0.3, then just add ':1' to the router's hostname</comment>
543
544 <comment>SAMBA forwarding to an internal host (excess ports to cover Windows)</comment>
545 # <i>iptables -t nat -I PREROUTING -p tcp --dport 135 -i ${WAN} -j DNAT --to 192.168.0.2</i>
546 # <i>iptables -t nat -I PREROUTING -p tcp --dport 139 -i ${WAN} -j DNAT --to 192.168.0.2</i>
547 # <i>iptables -t nat -I PREROUTING -p tcp --dport 445 -i ${WAN} -j DNAT --to 192.168.0.2</i>
548 # <i>iptables -t nat -I PREROUTING -p udp --dport 137:138 -i ${WAN} -j DNAT --to 192.168.0.2</i>
549 # <i>iptables -t nat -I PREROUTING -p udp --dport 445 -i ${WAN} -j DNAT --to 192.168.0.2</i>
550
551 <comment>Bittorrent forwarding</comment>
552 # <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i ${WAN} -j DNAT --to 192.168.0.2</i>
553
554 <comment>eDonkey/eMule forwarding</comment>
555 # <i>iptables -t nat -A PREROUTING -p tcp --dport 4662 -i ${WAN} -j DNAT --to 192.168.0.55</i>
556
557 <comment>Game Cube Warp Pipe support</comment>
558 # <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i ${WAN} -j DNAT --to 192.168.0.56</i>
559
560 <comment>Playstation 2 Online support</comment>
561 # <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
562 # <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
563
564 <comment>Xbox Live</comment>
565 # <i>iptables -t nat -A PREROUTING -p tcp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
566 # <i>iptables -t nat -A PREROUTING -p udp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
567 # <i>iptables -t nat -A PREROUTING -p udp --dport 88 -i ${WAN} -j DNAT --to 192.168.0.69</i>
568 </pre>
569
570 <note>
571 If you have other common / cool examples, please <mail
572 link="vapier@gentoo.org">e-mail me</mail>.
573 </note>
574
575 </body>
576 </section>
577
578 <section>
579 <title>Identd (for IRC)</title>
580 <body>
581
582 <p>
583 Internet Relay Chat utilizes the ident service pretty heavily. Now that the
584 IRC clients are behind the router, we need a way to host ident for both the
585 router and the clients. One such server has been created called
586 <c>midentd</c>.
587 </p>
588
589 <pre caption="Setting up ident">
590 # <i>emerge midentd</i>
591 # <i>rc-update add midentd default</i>
592 # <i>/etc/init.d/midentd start</i>
593 </pre>
594
595 <p>
596 There are a few other ident servers in portage. Depending on your needs, I
597 would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
598 </p>
599
600 </body>
601 </section>
602
603 <!--
604 <section>
605 <title>Traffic Shaping</title>
606 <body>
607 <p>
608 This is an attempt to simply and Gentooify the <uri link="http://www.tldp.org/HOWTO/ADSL-Bandwidth-Management-HOWTO/">ADSL Bandwidth Management HOWTO</uri>
609 found over at the TLDP. Feel free to refer to the original document
610 for more details.
611 </p>
612
613 <p>
614 Here we will be setting up what some people refer to as a "Packet Shaper",
615 <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
616 or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
617 Simply put, we want to setup rules on our router that will slow down
618 certain activities (like sending large e-mails or downloading from P2P
619 networks) while keeping other activities (like browsing the web or playing
620 online video games) reasonably fast. A 30 second difference in a video
621 game is a lot worse than a 30 second difference in downloading large
622 files :).
623 </p>
624
625 <p>
626 The first thing is to make sure your kernel has all the features added to
627 it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
628 information. Next, you will need to <c>emerge iptables iputils</c> so that
629 you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
630 commands.
631 </p>
632
633 <p>
634 Before we jump into the commands, let's cover a little of the theory. The
635 way this whole system works is to classify common network streams and then
636 to prioritize them. You use iptables to classify network streams, iputils
637 to define the different priority levels, and the kernel to adjust speeds.
638 Just remember that although you can control outbound traffic pretty tightly
639 (from the LAN to the WAN), your ability to control inbound traffic (from
640 the WAN to the LAN) is somewhat limited. Just remember that the following
641 examples are to get your feet wet; if you want more then I'd suggest
642 reading up on the subject. In this example, we will be using the
643 <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
644 packet scheduling algorithm. Still with me? Great, let's start shaping :).
645 </p>
646
647 <pre caption="Setup">
648 DEV=eth1 <comment>NIC connected to WAN</comment>
649 RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
650 RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
651
652 <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
653 ip link set dev ${DEV} qlen 30
654 tc qdisc add dev ${DEV} root handle 1: htb default 45
655 tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
656 </pre>
657
658 <p>
659 Here we initialized the system which will be used to prioritize all of
660 our network traffic. We created our queue, told it to use the HTB
661 algorithm, and set the default classification level to '45'. The
662 default is completely arbitrary, as are the levels we choose from
663 here on out. The only thing that matters is how the levels compare
664 relatively; a level '10' packet will be given preference over a
665 level '45' packet. Let's move on to declaring different levels.
666 </p>
667
668 <pre caption="Declaring levels">
669 tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
670 tc qdisc add dev $DEV parent 1:10 handle 10: sfq
671 </pre>
672 </body>
673 </section>
674 -->
675
676 <section>
677 <title>Time Server</title>
678 <body>
679
680 <p>
681 Keeping your system time correct is essential in maintaining a healthy system.
682 One of the most common ways of accomplishing this is with the Network Time
683 Protocol (NTP) and the ntp package (which provides implementations for both
684 server and client).
685 </p>
686
687 <p>
688 Many people run ntp clients on their computers. Obviously, the more clients in
689 the world, the larger the load the ntp servers need to shoulder. In
690 environments like home networks though, we can help keep the load down on
691 public servers while still providing the proper time to all our computers. As
692 an added bonus, our private updates will be a lot faster for the clients too!
693 All we have to do is run a ntp server on our router that synchronizes itself
694 with the public internet servers while providing the time to the rest of the
695 computers in the network. To get started, simply <c>emerge ntp</c> on the
696 router.
697 </p>
698
699 <pre caption="Setting up the NTP server">
700 # <i>nano /etc/conf.d/ntp-client</i>
701 <comment>Customize if you wish but the defaults should be fine</comment>
702 # <i>rc-update add ntp-client default</i>
703
704 # <i>nano /etc/ntp.conf</i>
705 <comment>Add the follwing lines:</comment>
706 restrict default ignore
707 restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
708 <comment>These will allow only ntp clients with an IP
709 address in the 192.168.0.xxx range to use your ntp server</comment>
710 # <i>nano /etc/conf.d/ntpd</i>
711 <comment>Customize if you wish but the defaults should be fine</comment>
712 # <i>rc-update add ntpd default</i>
713
714 # <i>/etc/init.d/ntp-client start</i>
715 # <i>/etc/init.d/ntpd start</i>
716 </pre>
717
718 <note>
719 You should make sure that you allow inbound and outbound communication on the
720 ntp port (123/udp) when setting up the server. The client just needs outbound
721 access on port 123 over udp.
722 </note>
723
724 <p>
725 Now, on your clients, have them <c>emerge ntp</c> also. However, we will just
726 run the ntp client so setup is a lot simpler.
727 </p>
728
729 <pre caption="Setting up a NTP client">
730 # <i>nano /etc/conf.d/ntp-client</i>
731 <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
732 # <i>rc-update add ntp-client default</i>
733 # <i>/etc/init.d/ntp-client start</i>
734 </pre>
735
736 </body>
737 </section>
738
739 <section>
740 <title>Rsync Server</title>
741 <body>
742
743 <p>
744 For those who run multiple Gentoo boxes on the same lan, you often want to
745 keep from having every machine running <c>emerge sync</c> with remote
746 servers. By setting up a local rsync, you save on both your bandwidth and
747 the Gentoo rsync servers' bandwidth. It's pretty simple to do.
748 </p>
749
750 <note>
751 For a much more in-depth rsync guide, please see the official <uri
752 link="/doc/en/rsync.xml#local">rsync guide</uri>.
753 </note>
754
755 <p>
756 Since every Gentoo machine requires rsync, theres no need to emerge it. Edit
757 the default <path>/etc/rsyncd.conf</path> config file, uncomment the
758 <c>[gentoo-portage]</c> section, and make sure you add an <c>address</c>
759 option. All the other defaults should be fine.
760 </p>
761
762 <pre caption="Rsync server config">
763 pid file = /var/run/rsyncd.pid
764 use chroot = yes
765 read only = yes
766 address = 192.168.0.1
767
768 [gentoo-portage]
769 path = /mnt/space/portage
770 comment = Gentoo Linux Portage tree
771 exclude = /distfiles /packages
772 </pre>
773
774 <p>
775 Then you need to start the service (again, the defaults are OK).
776 </p>
777
778 <pre caption="Starting the rsync server">
779 # <i>/etc/init.d/rsyncd start</i>
780 # <i>rc-update add rsyncd default</i>
781 </pre>
782
783 <p>
784 Only thing left is to set tell your clients to sync against the router.
785 </p>
786
787 <pre caption="Client SYNC settings in make.conf">
788 SYNC="rsync://192.168.0.1/gentoo-portage"
789 </pre>
790
791 </body>
792 </section>
793
794 <section>
795 <title>Mail Server</title>
796 <body>
797
798 <p>
799 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP) server
800 on the router. You may have your own reason for wanting to do so, but I run it
801 so that the users see mail as being sent instantly and the work of
802 retrying/routing is left up to the mail server. Some ISPs also don't allow for
803 mail relaying for accounts that aren't part of their network (like Verizon).
804 Also, you can easily throttle the delivery of mail so that large attachments
805 won't seriously lag your connection for half an hour.
806 </p>
807
808 <pre caption="Setting up SMTP">
809 # <i>emerge netqmail</i>
810 <comment>make sure the output of `hostname` is correct</comment>
811 # <i>emerge --config netqmail</i>
812 # <i>iptables -I INPUT -p tcp --dport smtp ! -i ${LAN} -j REJECT</i>
813 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
814 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
815 # <i>cd /etc/tcprules.d</i>
816 # <i>nano tcp.qmail-smtp</i>
817 <!--
818 # <i>cd /etc</i>
819 # <i>nano tcp.smtp</i>
820 -->
821 <comment>Add an entry like so to the allow section:</comment>
822 192.168.0.:allow,RELAYCLIENT=""
823 <!--
824 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
825 # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
826 -->
827 # <i>make</i>
828 # <i>rc-update add svscan default</i>
829 # <i>/etc/init.d/svscan start</i>
830 </pre>
831
832 <p>
833 I'm a huge fan of qmail, but you're free to use a different mta :). When you
834 setup e-mail on the hosts in your network, tell them that their SMTP server is
835 192.168.0.1 and everything should be peachy. You might want to visit the <uri
836 link="http://netqmail.org/">netqmail homepage</uri> for more documentation.
837 </p>
838
839 </body>
840 </section>
841
842 <!--
843 <section>
844 <title>E-mail Virus Scanning</title>
845 <body>
846 <p>
847 If you'd like to provide e-mail virus scanning for your users, but
848 don't want to have to install a virus scanner on every single machine,
849 then <c>pop3vscan</c> may just be the thing for you; a transparent
850 Post Office Protocol (POP) scanner.
851 </p>
852
853 <pre caption="Setting up pop3vscan">
854 TODO
855 </pre>
856
857 </body>
858 </section>
859 -->
860
861 <section>
862 <title>Full DHCP Server</title>
863 <body>
864
865 <p>
866 Earlier we used dnsmasq to provide DHCP service to all our clients. For most
867 people with a simple small LAN, this is perfect. But you may need something
868 with more features. Thus we turn to a full-featured DHCP server as provided
869 by the <uri link="http://www.isc.org/products/DHCP">ISC</uri> folks.
870 </p>
871
872 <pre caption="Setting up dhcpd">
873 # <i>emerge dhcp</i>
874 # <i>nano /etc/dhcp/dhcpd.conf</i>
875 <comment>(Here is a sample configuration file:)</comment>
876 authoritative;
877 ddns-update-style interim;
878 subnet 192.168.0.0 netmask 255.255.255.0 {
879 range 192.168.0.100 192.168.0.250;
880 default-lease-time 259200;
881 max-lease-time 518400;
882 option subnet-mask 255.255.255.0;
883 option broadcast-address 192.168.0.255;
884 option routers 192.168.0.1;
885 option domain-name-servers 192.168.0.1;
886 }
887 # <i>nano /etc/conf.d/dhcpd</i>
888 <comment>(Set IFACE="eth0")</comment>
889 # <i>rc-update add dhcpd default</i>
890 # <i>/etc/init.d/dhcpd start</i>
891 </pre>
892
893 <p>
894 This is the minimal setup required to replace the dnsmasq DHCP functionality
895 that we used earlier. Speaking of which, you did remember to disable the DHCP
896 features in dnsmasq didn't you? If not, you should do so now (just comment
897 out the <c>dhcp-range</c> setting in <path>/etc/dnsmasq.conf</path> and restart
898 the service).
899 </p>
900
901 </body>
902 </section>
903
904 <section>
905 <title>Connect Another LAN (or two or three or ...)</title>
906 <body>
907
908 <p>
909 Sometimes you have need of connecting the router to another LAN. Maybe you
910 want to hook up a group of friends temporarily, or you're a neat freak and
911 want to section off different groups of computers, or you're just really
912 really bored. Whatever the reasons, extending the router to other LAN
913 networks should be pretty straightforward. In the following examples, I will
914 assume that this new network is connected via a third ethernet card, namely
915 <c>eth2</c>.
916 </p>
917
918 <p>
919 First you need to configure the interface. Just take the instructions in the
920 <uri link="#doc_chap4_pre1">4.1 code listing</uri> and replace <c>eth0</c>
921 with <c>eth2</c> and <c>192.168.0</c> with <c>192.168.1</c>.
922 </p>
923
924 <p>
925 Then you need to tweak dnsmasq to service the new interface. Just edit the
926 <path>/etc/conf.d/dnsmasq</path> file again and append <c>-i eth2</c> to
927 DNSMASQ_OPTS; using -i multiple times is OK. Then edit
928 <path>/etc/dnsmasq.conf</path> and add another line like the dhcp-range line
929 in the <uri link="#doc_chap5_pre1">5.1 code listing</uri>, replacing
930 <c>192.168.0</c> with <c>192.168.1</c>. Having multiple dhcp-range lines is
931 OK too.
932 </p>
933
934 <p>
935 Finally, see the rules in the <uri link="#doc_chap5_pre2">5.2 code
936 listing</uri> and duplicate the rules that have <c>-i ${LAN}</c> in them. You
937 may want to create another variable, say <c>LAN2</c>, to make things easier.
938 </p>
939
940 </body>
941 </section>
942
943 </chapter>
944
945 <chapter>
946 <title>Troubleshooting</title>
947
948 <section>
949 <title>Useful Tools</title>
950 <body>
951
952 <p>
953 If you're having trouble getting your computers to communicate, you may way to
954 try out the following tools (they can all be found in the <c>net-analyzer</c>
955 portage category):
956 </p>
957
958 <table>
959 <tr>
960 <th>Utility</th>
961 <th>Description</th>
962 </tr>
963 <tr>
964 <ti>wireshark</ti>
965 <ti>GUI tool to view all raw network data according to filters</ti>
966 </tr>
967 <tr>
968 <ti>tcpdump</ti>
969 <ti>Console tool to dump all raw network data according to filters</ti>
970 </tr>
971 <tr>
972 <ti>iptraf</ti>
973 <ti>ncurses based IP LAN monitor</ti>
974 </tr>
975 <tr>
976 <ti>ettercap</ti>
977 <ti>ncurses based network monitor/control</ti>
978 </tr>
979 </table>
980
981 </body>
982 </section>
983
984 <section>
985 <title>DHCP Fails To Start</title>
986 <body>
987
988 <p>
989 When starting the dhcp init.d script for the first time, it may fail to load
990 but neglect to give you any useful info.
991 </p>
992
993 <pre caption="DHCP Failing Example">
994 # <i>/etc/init.d/dhcp start</i>
995 * Setting ownership on dhcp.leases ... [ ok ]
996 * Starting dhcpd ... [ !! ]
997 </pre>
998
999 <p>
1000 The trick is to know where dhcpd is sending its output. Simply browse to
1001 <path>/var/log</path> and read the log files. Since the exact log file depends
1002 on the package you are using as a syslog, try running <c>grep -Rl dhcpd
1003 /var/log</c> to narrow down the possibilities. Chances are you made a typo in
1004 your config file. You could also try running <c>dhcpd -d -f</c> (short for
1005 debug / foreground) and debug the error based upon the output.
1006 </p>
1007
1008 </body>
1009 </section>
1010
1011 <section>
1012 <title>Incorrect MTU Value</title>
1013 <body>
1014
1015 <p>
1016 If you experience odd errors (such as not being able to access some webpages
1017 while others load fine), you may be having Path MTU Discovery trouble. The
1018 quick way to test is to run this iptables command:
1019 </p>
1020
1021 <pre caption="Circumvent MTU issues">
1022 # <i>iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu</i>
1023 </pre>
1024
1025 <p>
1026 This will affect all new connections, so just refresh the website you're having
1027 problems with in order to test. In case it helps, the standard MTU value for
1028 100mbit ethernet connections is <c>1500</c>; this value also applies to PPPoA.
1029 For PPPoE connections it is <c>1492</c>. For more info, you should read Chapter
1030 15 of the <uri link="http://lartc.org/howto/">Linux Advanced Routing &amp;
1031 Traffic Control HOWTO</uri>.
1032 </p>
1033
1034 <p>
1035 If that command does not work for you, you may want to try putting the rule
1036 into the mangle table. Simply add <c>-t mangle</c> to the command.
1037 </p>
1038
1039 </body>
1040 </section>
1041
1042 <section>
1043 <title>Unable to connect two machines directly</title>
1044 <body>
1045
1046 <p>
1047 If (for whatever reason) you want to connect two machines directly together
1048 without a hub or switch, a regular ethernet cable will likely not work, unless
1049 you have an Auto MDI/MDI-X (also known as "autosensing") capable network
1050 adapter. You will need a different cable called a crossover cable. This <uri
1051 link="http://en.wikipedia.org/wiki/Ethernet_crossover_cable">Wikipedia</uri>
1052 page explains the low level details.
1053 </p>
1054
1055 </body>
1056 </section>
1057
1058 </chapter>
1059
1060 <chapter>
1061 <title>Final Notes</title>
1062 <section>
1063 <body>
1064
1065 <p>
1066 I have no final notes other than if you experience any troubles with the guide,
1067 please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with <uri
1068 link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If you have
1069 some interesting bits you think would enhance this guide, by all means send it
1070 my way for inclusion.
1071 </p>
1072
1073 </body>
1074 </section>
1075 </chapter>
1076 </guide>

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