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Wed Mar 29 01:30:31 2006 UTC (8 years, 4 months ago) by vapier
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some baselayout/dnsmasq tweaks from Davide Giannotti

1 vapier 1.1 <?xml version='1.0' encoding='UTF-8'?>
2     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 vapier 1.43 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.42 2006/03/17 10:17:04 neysx Exp $ -->
4 vapier 1.1
5 vapier 1.36 <guide link="/doc/en/home-router-howto.xml" lang="en">
6 vapier 1.1 <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 vapier 1.36 <!-- The content of this document is released into the public domain -->
18     <license/>
19    
20 vapier 1.43 <version>1.26</version>
21     <date>2006-03-28</date>
22 vapier 1.1
23     <chapter>
24     <title>Introduction</title>
25     <section>
26     <body>
27    
28     <p>
29 neysx 1.23 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 vapier 1.1 </p>
35    
36     <p>
37 neysx 1.23 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 rp-pppoe), and conclude
40     with more elaborate and fun things that can be done (port forwarding, traffic
41     shaping, proxies/caching, etc...).
42 vapier 1.1 </p>
43    
44     <p>
45 neysx 1.23 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 vapier 1.1 </p>
51    
52     <p>
53     The conventions used in this guide are:
54     </p>
55 neysx 1.23
56 vapier 1.1 <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 vapier 1.3 <li>router is running Linux 2.4 or 2.6; you're on your own with 2.0/2.2</li>
62 vapier 1.1 </ul>
63    
64     <impo>
65 neysx 1.23 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 vapier 1.1 </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 neysx 1.23 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 vapier 1.1 </p>
85 neysx 1.23
86 vapier 1.1 <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 neysx 1.23
105 vapier 1.1 <p>
106 neysx 1.23 If you do not see your two cards showing up and you're not sure what kind of
107 neysx 1.42 cards you have, try running <c>lspci | grep Ethernet</c>. You can get that from
108     <c>emerge pciutils</c>. Once you have this information, go into your kernel and
109     add support for the correct drivers.
110 vapier 1.1 </p>
111    
112     <p>
113 neysx 1.23 The next thing you'll need is support for iptables and NAT (and packet shaping
114 vapier 1.35 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 neysx 1.23 exercise however).
120 vapier 1.1 </p>
121 neysx 1.23
122 vapier 1.1 <pre caption="Network Options">
123 neysx 1.23 Networking options ---&gt;
124     [*] TCP/IP networking
125     [*] IP: advanced router
126     [*] Network packet filtering (replaces ipchains)
127 vapier 1.20 <comment>If you use 2.4.x, you have to enable the following for DHCP:</comment>
128 neysx 1.23 [*] Socket Filtering
129 vapier 1.1
130 neysx 1.23 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 vapier 1.35
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 vapier 1.1 </pre>
160 neysx 1.23
161 vapier 1.1 <note>
162 neysx 1.23 Somethings may be slightly different in a 2.4 vs 2.6 kernel, but you should be
163     able to figure it out :).
164 vapier 1.1 </note>
165    
166     </body>
167     </section>
168     </chapter>
169    
170     <chapter>
171     <title>Hug the WAN (a.k.a. The Internet)</title>
172    
173     <section>
174     <title>Intro</title>
175     <body>
176 neysx 1.23
177 vapier 1.1 <p>
178 neysx 1.23 There are many ways to connect to the internet so I'll just cover the ones I'm
179     familiar with. That leaves us with ADSL (PPPoE) and cable modems
180     (static/dynamic). If there are other methods out there, feel free to write up
181     a little blurb and e-mail me. Feel free to skip any of the following sections
182     in this chapter that don't apply to you. This chapter is just about getting
183     the router connected to the internet via eth1.
184 vapier 1.1 </p>
185 neysx 1.23
186 vapier 1.1 </body>
187     </section>
188     <section>
189     <title>ADSL and PPPoE</title>
190     <body>
191    
192     <p>
193 neysx 1.23 All the fancy PPPoE software has been bundled up into one little nice package
194     nowadays called <uri link="http://www.roaringpenguin.com/">Roaring
195     Penguin</uri>. Simply <c>emerge rp-pppoe</c> and you'll be on your way.
196     Remember how I said you'll need username/password information? Well I wasn't
197     lying so I hope you have it now! Load up <path>/etc/ppp/pppoe.conf</path> in
198 vapier 1.1 your favorite editor and set it up.
199     </p>
200    
201 vapier 1.8 <note>
202 vapier 1.39 In order for the following net settings to work, you must have
203     baselayout-1.11.14 or later installed on your system.
204 vapier 1.8 </note>
205    
206 vapier 1.1 <pre caption="Setting up eth1">
207     <comment>(Replace 'vla9h924' with your username and 'password' with your password)</comment>
208    
209     # <i>nano /etc/ppp/pap-secrets</i>
210 neysx 1.23 <comment># client server secret</comment>
211     "vla9h924" * "password"
212 vapier 1.1 # <i>nano /etc/conf.d/net</i>
213 vapier 1.39 <comment>Tell baselayout to use adsl for your eth1:</comment>
214 vapier 1.25 config_eth1=( "adsl" )
215 vapier 1.39 user_eth1=( "vla9h924" )
216 vapier 1.30 # <i>ln -s net.lo /etc/init.d/net.eth1</i>
217 vapier 1.1 # <i>rc-update add net.eth1 default</i>
218     # <i>/etc/init.d/net.eth1 start</i>
219     </pre>
220    
221 vapier 1.3 <warn>
222 vapier 1.39 When the DSL interface comes up, it will create ppp0. Although your NIC is
223     called eth1, the IP is actually bound to ppp0. From now on, when you see
224     examples that utilize 'eth1', substitute with 'ppp0'.
225 vapier 1.3 </warn>
226 vapier 1.1
227     </body>
228     </section>
229    
230     <section>
231     <title>Cable and/or dynamic/static IP</title>
232     <body>
233    
234     <p>
235 vapier 1.4 If you have a static IP then you will need a few more details than if
236 vapier 1.1 you have a dynamic IP. For static users, you will need your IP,
237     gateway, and DNS servers.
238     </p>
239    
240     <pre caption="Setting up eth1">
241     <comment>Dynamic IP Users:</comment>
242     # <i>emerge dhcpcd</i>
243     # <i>nano /etc/conf.d/net</i>
244 neysx 1.23 <comment>You'll need an entry like so:</comment>
245 vapier 1.25 config_eth1=( "dhcp" )
246 vapier 1.1
247     <comment>Static IP Users:</comment>
248     # <i>nano /etc/conf.d/net</i>
249 neysx 1.23 <comment>You'll need entries like so:</comment>
250 vapier 1.43 config_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" )
251 neysx 1.23 routes_eth1=( "default gw 66.92.78.1" )
252 vapier 1.1 # <i>nano /etc/resolv.conf</i>
253 neysx 1.23 <comment>Add one line per DNS server:</comment>
254     nameserver 123.123.123.123
255 vapier 1.1
256     <comment>Dynamic and Static Setup:</comment>
257 vapier 1.30 # <i>ln -s net.lo /etc/init.d/net.eth1</i>
258 vapier 1.1 # <i>rc-update add net.eth1 default</i>
259     # <i>/etc/init.d/net.eth1 start</i>
260     </pre>
261    
262     <p>
263     You should be all set to go now.
264     </p>
265    
266     </body>
267     </section>
268     </chapter>
269    
270     <chapter>
271     <title>Hug the LAN (bring along some friends)</title>
272     <section>
273     <body>
274    
275     <p>
276     This step is a breeze compared to the previous one.
277     </p>
278    
279     <pre caption="Setting up eth0">
280     # <i>nano /etc/conf.d/net</i>
281 neysx 1.23 <comment>Add a line like the following:</comment>
282 vapier 1.43 config_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )
283 vapier 1.1 # <i>rc-update add net.eth0 default</i>
284     # <i>/etc/init.d/net.eth0 start</i>
285     </pre>
286    
287     </body>
288     </section>
289     </chapter>
290    
291     <chapter>
292     <title>LAN Services (because we're nice people)</title>
293    
294     <section>
295     <title>DHCP Server</title>
296     <body>
297 neysx 1.23
298 vapier 1.1 <p>
299 neysx 1.23 I bet it'd be nice if everyone else in your house could just plug their
300     computers into the network and things would just work. No need to remember
301     mind-numbing details or make them stare at confusing configuration screens!
302     Life would be grand eh? Introducing the Dynamic Host Configuration Protocol
303     (DHCP) and why you should care.
304 vapier 1.1 </p>
305    
306 vapier 1.2 <p>
307     DHCP is exactly what its name implies. It's a protocol that allows you
308 neysx 1.23 to dynamically configure other hosts automatically. You run a DHCP server on
309 vapier 1.33 the router, give it all the information about your network (valid IPs,
310 neysx 1.23 DNS servers, gateways, etc...), and then when the other hosts start up, they
311     run a DHCP client to automatically configure themselves. No fuss, no muss!
312     For more information about DHCP, you can always visit <uri
313     link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
314 vapier 1.2 </p>
315    
316 vapier 1.33 <p>
317     We'll use a package called dnsmasq which provides both DHCP and DNS services.
318     For now lets just focus on the DHCP aspect. Note that if you want to run a
319     different DHCP server, you can find another example in the Fun Things chapter.
320     Also, if you wish to tinker with the DHCP server settings, just read the
321     comments in <path>/etc/dnsmasq.conf</path>. All the defaults should work fine
322     though.
323     </p>
324    
325     <pre caption="Setting up a DHCP server">
326     # <i>emerge dnsmasq</i>
327     # <i>nano /etc/dnsmasq.conf</i>
328 vapier 1.43 <comment>Add this line to enable dhcp:</comment>
329 vapier 1.33 dhcp-range=192.168.0.100,192.168.0.250,72h
330 vapier 1.43 <comment>Restrict dnsmasq to just the LAN interface</comment>
331     interface=eth0
332 vapier 1.33
333     # <i>rc-update add dnsmasq default</i>
334     # <i>/etc/init.d/dnsmasq start</i>
335 vapier 1.1 </pre>
336    
337     <p>
338 neysx 1.23 Now your little router is a bona-fide DHCP server! Plugin those computers and
339     watch them work! With Windows systems you should go into the TCP/IP Properties
340     and select the 'Obtain an IP address automatically' and 'Obtain DNS server
341     address automatically' options. Sometimes the changes aren't instantaneous, so
342 vapier 1.31 you may have to open a command prompt and run <c>ipconfig /release</c> and
343 neysx 1.23 <c>ipconfig /renew</c>. But enough about Windows, let's get back to our
344     favorite penguin.
345 vapier 1.1 </p>
346 neysx 1.23
347 vapier 1.1 </body>
348     </section>
349    
350     <section>
351     <title>DNS Server</title>
352     <body>
353 neysx 1.23
354 vapier 1.2 <p>
355 neysx 1.23 When people want to visit a place on the internet, they remember names, not a
356 vapier 1.33 string of funky numbers. After all, what's easier to remember, ebay.com or
357 neysx 1.23 66.135.192.87? This is where the DNS steps in. DNS servers run all over the
358     internet, and whenever someone wants to visit 'ebay.com', these servers turn
359     'ebay.com' (what we understand) into '66.135.192.87' (what our computers
360     understand). For more information about DNS, you can always visit <uri
361     link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
362 vapier 1.2 </p>
363 vapier 1.1
364     <p>
365 vapier 1.33 Since we're using dnsmasq for our DHCP server, and it includes a DNS server,
366     you've got nothing left to do here! Your little router is already providing
367     DNS to its DHCP clients. Bet you wish everything was this easy ;).
368 vapier 1.1 </p>
369    
370     <p>
371 vapier 1.33 You're welcome to choose other DNS servers if you're more comfortable with
372     them, but the reason dnsmasq is great is because it was designed to do exactly
373     what we want and nothing more. It's a little DNS caching/forwarding server for
374     local networks. We're not looking to provide DNS for our own domain here, just
375     offer simple DNS services to everyone else on our LAN.
376 vapier 1.1 </p>
377    
378     </body>
379     </section>
380    
381     <section>
382 vapier 1.4 <title>NAT (a.k.a. IP-masquerading)</title>
383 vapier 1.1 <body>
384    
385     <p>
386 neysx 1.23 At this point, people on your network can talk to each other and they can look
387     up hostnames via DNS, but they still can't actually connect to the internet.
388     While you may think that's great (more bandwidth for you!), I bet they're not
389     too happy just yet.
390 vapier 1.1 </p>
391    
392 vapier 1.2 <p>
393 vapier 1.33 This is where Network Address Translation (NAT) steps in. NAT is a way of
394     connecting multiple computers in a private LAN to the internet when you have a
395     smaller number of public IP addresses available to you. Typically you are given
396     1 IP by your ISP, but you want to let your whole house connect to the internet.
397     NAT is the magic that makes this possible. For more information about NAT, you
398     can always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
399 vapier 1.2 </p>
400    
401     <note>
402 neysx 1.23 Before we get started, make sure you have iptables on your system. Although it
403     is automatically installed on most systems, you may not have it. If you don't,
404     just run <c>emerge iptables</c>.
405 vapier 1.2 </note>
406    
407 vapier 1.1 <pre caption="Setting up iptables">
408     <comment>First we flush our current rules</comment>
409     # <i>iptables -F</i>
410     # <i>iptables -t nat -F</i>
411    
412 vapier 1.33 <comment>Setup default policies to handle unmatched traffic</comment>
413 vapier 1.32 # <i>iptables -P INPUT ACCEPT</i>
414     # <i>iptables -P OUTPUT ACCEPT</i>
415     # <i>iptables -P FORWARD DROP</i>
416    
417 vapier 1.30 <comment>Copy and paste these examples ...</comment>
418     # <i>export LAN=eth0</i>
419     # <i>export WAN=eth1</i>
420    
421 vapier 1.1 <comment>Then we lock our services so they only work from the LAN</comment>
422 vapier 1.30 # <i>iptables -I INPUT 1 -i ${LAN} -j ACCEPT</i>
423 vapier 1.1 # <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
424 vapier 1.30 # <i>iptables -A INPUT -p UDP --dport bootps -i ! ${LAN} -j REJECT</i>
425     # <i>iptables -A INPUT -p UDP --dport domain -i ! ${LAN} -j REJECT</i>
426 vapier 1.1
427 vapier 1.21 <comment>(Optional) Allow access to our ssh server from the WAN</comment>
428 vapier 1.30 # <i>iptables -A INPUT -p TCP --dport ssh -i ${WAN} -j ACCEPT</i>
429 vapier 1.21
430 vapier 1.1 <comment>Drop TCP / UDP packets to privileged ports</comment>
431 vapier 1.30 # <i>iptables -A INPUT -p TCP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
432     # <i>iptables -A INPUT -p UDP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
433 vapier 1.1
434     <comment>Finally we add the rules for NAT</comment>
435 vapier 1.30 # <i>iptables -I FORWARD -i ${LAN} -d 192.168.0.0/255.255.0.0 -j DROP</i>
436     # <i>iptables -A FORWARD -i ${LAN} -s 192.168.0.0/255.255.0.0 -j ACCEPT</i>
437     # <i>iptables -A FORWARD -i ${WAN} -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
438     # <i>iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE</i>
439 vapier 1.1 <comment>Tell the kernel that ip forwarding is OK</comment>
440     # <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i>
441     # <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
442    
443     <comment>This is so when we boot we don't have to run the rules by hand</comment>
444     # <i>/etc/init.d/iptables save</i>
445     # <i>rc-update add iptables default</i>
446 vapier 1.14 # <i>nano /etc/sysctl.conf</i>
447     <comment>Add/Uncomment the following lines:
448     net.ipv4.ip_forward = 1
449     net.ipv4.conf.default.rp_filter = 1</comment>
450 vapier 1.1 </pre>
451    
452     <p>
453 neysx 1.23 Once you've typed out all of that, the rest of your network should now be able
454     to use the internet as if they were directly connected themselves.
455 vapier 1.1 </p>
456    
457 vapier 1.3 </body>
458     </section>
459     </chapter>
460    
461     <chapter>
462     <title>Fun Things (for a rainy day)</title>
463    
464     <section>
465     <title>Intro</title>
466     <body>
467 neysx 1.23
468 vapier 1.1 <p>
469 neysx 1.23 Believe it or not, you're done :). From here on out, I'll cover a bunch of
470     common topics that may interest you. Everything in this chapter is completely
471     optional.
472 vapier 1.1 </p>
473 neysx 1.23
474 vapier 1.3 </body>
475     </section>
476 vapier 1.1
477 vapier 1.3 <section>
478     <title>Port Forwarding</title>
479     <body>
480 neysx 1.23
481 vapier 1.3 <p>
482 neysx 1.23 Sometimes you would like to be able to host services on a computer behind the
483     router, or just to make your life easier when connecting remotely. Perhaps you
484     want to run a FTP, HTTP, SSH, or VNC server on one or more machines behind your
485     router and be able to connect to them all. The only caveat is that you can
486     only have one service/machine combo per port. For example, there is no
487     practical way to setup three FTP servers behind your router and then try to
488     connect to them all through port 21; only one can be on port 21 while the
489     others would have to be on say port 123 and port 567.
490 vapier 1.3 </p>
491    
492     <p>
493 neysx 1.23 All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING
494 vapier 1.30 [-p protocol] --dport [external port on router] -i ${WAN} -j DNAT --to [ip/port
495 vapier 1.33 to forward to]</c>. Unfortunately, iptables does not accept hostnames when port
496     forwarding. If you are forwarding an external port to the same port on the
497     internal machine, you can omit the destination port. See the iptables(8) man
498     page for more information.
499 vapier 1.3 </p>
500    
501 swift 1.28 <pre caption="Running the iptables commands">
502 vapier 1.30 <comment>Copy and paste these examples ...</comment>
503     # <i>export LAN=eth0</i>
504     # <i>export WAN=eth1</i>
505    
506 vapier 1.3 <comment>Forward port 2 to ssh on an internal host</comment>
507 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i ${WAN} -j DNAT --to 192.168.0.2:22</i>
508 vapier 1.3
509     <comment>FTP forwarding to an internal host</comment>
510 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i ${WAN} -j DNAT --to 192.168.0.56</i>
511 vapier 1.3
512     <comment>HTTP forwarding to an internal host</comment>
513 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i ${WAN} -j DNAT --to 192.168.0.56</i>
514 vapier 1.3
515     <comment>VNC forwarding for internal hosts</comment>
516 vapier 1.30 # <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i ${WAN} -j DNAT --to 192.168.0.2</i>
517     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i ${WAN} -j DNAT --to 192.168.0.3:5900</i>
518 vapier 1.3 <comment>If you want to VNC in to 192.168.0.3, then just add ':1' to the router's hostname</comment>
519    
520     <comment>Bittorrent forwarding</comment>
521 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i ${WAN} -j DNAT --to 192.168.0.2</i>
522 vapier 1.15
523 vapier 1.33 <comment>eDonkey/eMule forwarding</comment>
524     # <i>iptables -t nat -A PREROUTING -p tcp --dport 4662 -i ${WAN} -j DNAT --to 192.168.0.55</i>
525    
526 vapier 1.15 <comment>Game Cube Warp Pipe support</comment>
527 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i ${WAN} -j DNAT --to 192.168.0.56</i>
528 vapier 1.15
529 vapier 1.33 <comment>Playstation 2 Online support</comment>
530 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
531     # <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
532 vapier 1.34
533     <comment>Xbox Live</comment>
534     # <i>iptables -t nat -A PREROUTING -p tcp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
535     # <i>iptables -t nat -A PREROUTING -p udp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
536     # <i>iptables -t nat -A PREROUTING -p udp --dport 88 -i ${WAN} -j DNAT --to 192.168.0.69</i>
537 vapier 1.3 </pre>
538    
539     <note>
540 neysx 1.37 If you have other common / cool examples, please <mail
541     link="vapier@gentoo.org">e-mail me</mail>.
542 vapier 1.3 </note>
543 neysx 1.23
544 vapier 1.3 </body>
545     </section>
546    
547     <section>
548     <title>Identd (for IRC)</title>
549     <body>
550 neysx 1.23
551 vapier 1.3 <p>
552 neysx 1.23 Internet Relay Chat utilizes the ident service pretty heavily. Now that the
553     IRC clients are behind the router, we need a way to host ident for both the
554     router and the clients. One such server has been created called
555     <c>midentd</c>.
556 vapier 1.3 </p>
557    
558     <pre caption="Setting up ident">
559     # <i>emerge midentd</i>
560     # <i>rc-update add midentd default</i>
561     # <i>/etc/init.d/midentd start</i>
562     </pre>
563    
564     <p>
565 neysx 1.23 There are a few other ident servers in portage. Depending on your needs, I
566     would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
567 vapier 1.3 </p>
568 neysx 1.23
569 vapier 1.3 </body>
570     </section>
571    
572 vapier 1.5 <!--
573     <section>
574     <title>Traffic Shaping</title>
575     <body>
576     <p>
577     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>
578     found over at the TLDP. Feel free to refer to the original document
579     for more details.
580     </p>
581    
582     <p>
583     Here we will be setting up what some people refer to as a "Packet Shaper",
584     <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
585     or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
586     Simply put, we want to setup rules on our router that will slow down
587     certain activities (like sending large e-mails or downloading from P2P
588     networks) while keeping other activities (like browsing the web or playing
589     online video games) reasonably fast. A 30 second difference in a video
590     game is a lot worse than a 30 second difference in downloading large
591     files :).
592     </p>
593    
594     <p>
595     The first thing is to make sure your kernel has all the features added to
596     it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
597     information. Next, you will need to <c>emerge iptables iputils</c> so that
598     you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
599     commands.
600     </p>
601    
602     <p>
603     Before we jump into the commands, let's cover a little of the theory. The
604     way this whole system works is to classify common network streams and then
605     to prioritize them. You use iptables to classify network streams, iputils
606     to define the different priority levels, and the kernel to adjust speeds.
607     Just remember that although you can control outbound traffic pretty tightly
608     (from the LAN to the WAN), your ability to control inbound traffic (from
609     the WAN to the LAN) is somewhat limited. Just remember that the following
610     examples are to get your feet wet; if you want more then I'd suggest
611     reading up on the subject. In this example, we will be using the
612     <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
613     packet scheduling algorithm. Still with me? Great, let's start shaping :).
614     </p>
615    
616     <pre caption="Setup">
617     DEV=eth1 <comment>NIC connected to WAN</comment>
618     RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
619     RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
620    
621     <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
622     ip link set dev ${DEV} qlen 30
623     tc qdisc add dev ${DEV} root handle 1: htb default 45
624     tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
625     </pre>
626    
627     <p>
628     Here we initialized the system which will be used to prioritize all of
629     our network traffic. We created our queue, told it to use the HTB
630     algorithm, and set the default classification level to '45'. The
631     default is completely arbitrary, as are the levels we choose from
632     here on out. The only thing that matters is how the levels compare
633     relatively; a level '10' packet will be given preference over a
634     level '45' packet. Let's move on to declaring different levels.
635     </p>
636    
637     <pre caption="Declaring levels">
638     tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
639     tc qdisc add dev $DEV parent 1:10 handle 10: sfq
640     </pre>
641     </body>
642     </section>
643     -->
644    
645 vapier 1.3 <section>
646 vapier 1.9 <title>Time Server</title>
647     <body>
648 neysx 1.23
649 vapier 1.9 <p>
650 vapier 1.24 Keeping your system time correct is essential in maintaining a healthy system.
651 neysx 1.23 One of the most common ways of accomplishing this is with the Network Time
652     Protocol (NTP) and the ntp package (which provides implementations for both
653     server and client).
654 vapier 1.9 </p>
655    
656     <p>
657 neysx 1.23 Many people run ntp clients on their computers. Obviously, the more clients in
658     the world, the larger the load the ntp servers need to shoulder. In
659     environments like home networks though, we can help keep the load down on
660     public servers while still providing the proper time to all our computers. As
661     an added bonus, our private updates will be a lot faster for the clients too!
662     All we have to do is run a ntp server on our router that synchronizes itself
663     with the public internet servers while providing the time to the rest of the
664     computers in the network. To get started, simply <c>emerge ntp</c> on the
665 vapier 1.9 router.
666     </p>
667    
668     <pre caption="Setting up the NTP server">
669     # <i>nano /etc/conf.d/ntp-client</i>
670     <comment>Customize if you wish but the defaults should be fine</comment>
671     # <i>rc-update add ntp-client default</i>
672    
673     # <i>nano /etc/ntp.conf</i>
674 neysx 1.23 <comment>Add the follwing lines:</comment>
675 vapier 1.9 restrict default ignore
676     restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
677 neysx 1.23 <comment>These will allow only ntp clients with an IP
678     address in the 192.168.0.xxx range to use your ntp server</comment>
679 vapier 1.9 # <i>nano /etc/conf.d/ntpd</i>
680     <comment>Customize if you wish but the defaults should be fine</comment>
681 vapier 1.17 # <i>rc-update add ntpd default</i>
682 vapier 1.9
683     # <i>/etc/init.d/ntp-client start</i>
684     # <i>/etc/init.d/ntpd start</i>
685     </pre>
686    
687 vapier 1.22 <note>
688 neysx 1.23 You should make sure that you allow inbound and outbound communication on the
689     ntp port (123/udp) when setting up the server. The client just needs outbound
690     access on port 123 over udp.
691 vapier 1.22 </note>
692    
693 vapier 1.9 <p>
694 neysx 1.23 Now, on your clients, have them <c>emerge ntp</c> also. However, we will just
695     run the ntp client so setup is a lot simpler.
696 vapier 1.9 </p>
697    
698     <pre caption="Setting up a NTP client">
699     # <i>nano /etc/conf.d/ntp-client</i>
700     <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
701     # <i>rc-update add ntp-client default</i>
702     # <i>/etc/init.d/ntp-client start</i>
703     </pre>
704 neysx 1.23
705 vapier 1.9 </body>
706     </section>
707    
708     <section>
709 vapier 1.29 <title>Rsync Server</title>
710     <body>
711    
712     <p>
713     For those who run multiple Gentoo boxes on the same lan, you often want to
714     keep from having every machine running <c>emerge sync</c> with remote
715     servers. By setting up a local rsync, you save on both your bandwidth and
716     the Gentoo rsync servers' bandwidth. It's pretty simple to do.
717     </p>
718     <note>
719     For a much more in-depth rsync guide, please see the official <uri
720     link="/doc/en/rsync.xml#doc_chap4">rsync guide</uri>
721     </note>
722    
723     <p>
724     Since every Gentoo machine requires rsync, theres no need to emerge it. Edit
725     the default <path>/etc/rsyncd.conf</path> config file, uncomment the
726     <c>[gentoo-portage]</c> section, and make sure you add an <c>address</c>
727     option. All the other defaults should be fine.
728     </p>
729    
730     <pre caption="Rsync server config">
731     pid file = /var/run/rsyncd.pid
732     use chroot = yes
733     read only = yes
734     address = 192.168.0.1
735    
736     [gentoo-portage]
737 neysx 1.41 path = /mnt/space/portage
738     comment = Gentoo Linux Portage tree
739     exclude = /distfiles /packages
740 vapier 1.29 </pre>
741    
742     <p>
743     Then you need to start the service (again, the defaults are OK).
744     </p>
745    
746     <pre caption="Starting the rsync server">
747     # <i>/etc/init.d/rsyncd start</i>
748     # <i>rc-update add rsyncd default</i>
749     </pre>
750    
751     <p>
752     Only thing left is to set tell your clients to sync against the router.
753     </p>
754    
755     <pre caption="Client SYNC settings in make.conf">
756     SYNC="rsync://192.168.0.1/gentoo-portage"
757     </pre>
758    
759     </body>
760     </section>
761    
762     <section>
763 vapier 1.3 <title>Mail Server</title>
764     <body>
765 neysx 1.23
766 vapier 1.3 <p>
767 neysx 1.23 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP) server
768     on the router. You may have your own reason for wanting to do so, but I run it
769     so that the users see mail as being sent instantly and the work of
770     retrying/routing is left up to the mail server. Some ISPs also don't allow for
771     mail relaying for accounts that aren't part of their network (like Verizon).
772     Also, you can easily throttle the delivery of mail so that large attachments
773     won't seriously lag your connection for half an hour.
774 vapier 1.4 </p>
775    
776     <pre caption="Setting up SMTP">
777     # <i>emerge qmail</i>
778     <comment>make sure the output of `hostname` is correct</comment>
779     # <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
780 vapier 1.30 # <i>iptables -I INPUT -p tcp --dport smtp -i ! ${LAN} -j REJECT</i>
781 vapier 1.4 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
782 vapier 1.10 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
783 vapier 1.13 <!--
784 vapier 1.4 # <i>cd /etc/tcprules.d</i>
785     # <i>nano tcp.qmail-smtp</i>
786 vapier 1.13 -->
787     # <i>cd /etc</i>
788     # <i>nano tcp.smtp</i>
789 neysx 1.23 <comment>Add an entry like so to the allow section:</comment>
790     192.168.0.:allow,RELAYCLIENT=""
791 vapier 1.13 <!--
792 vapier 1.4 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
793 vapier 1.13 -->
794     # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
795 vapier 1.4 # <i>rc-update add svscan default</i>
796     # <i>/etc/init.d/svscan start</i>
797     </pre>
798    
799     <p>
800 neysx 1.23 I'm a huge fan of qmail, but you're free to use a different mta :). When you
801     setup e-mail on the hosts in your network, tell them that their SMTP server is
802     192.168.0.1 and everything should be peachy. You might want to visit the <uri
803     link="http://qmail.org/">qmail homepage</uri> for more documentation.
804 vapier 1.3 </p>
805 neysx 1.23
806 vapier 1.3 </body>
807     </section>
808    
809 vapier 1.4 <!--
810 vapier 1.3 <section>
811 vapier 1.4 <title>E-mail Virus Scanning</title>
812 vapier 1.3 <body>
813     <p>
814 vapier 1.4 If you'd like to provide e-mail virus scanning for your users, but
815     don't want to have to install a virus scanner on every single machine,
816     then <c>pop3vscan</c> may just be the thing for you; a transparent
817     Post Office Protocol (POP) scanner.
818 vapier 1.3 </p>
819 vapier 1.4
820     <pre caption="Setting up pop3vscan">
821     TODO
822     </pre>
823    
824 vapier 1.3 </body>
825     </section>
826 vapier 1.4 -->
827 vapier 1.3
828 vapier 1.33 <section>
829     <title>Full DHCP Server</title>
830     <body>
831    
832     <p>
833     Earlier we used dnsmasq to provide DHCP service to all our clients. For most
834     people with a simple small LAN, this is perfect. But you may need something
835     with more features. Thus we turn to a full-featured DHCP server as provided
836     by the <uri link="http://www.isc.org/products/DHCP">ISC</uri> folks.
837     </p>
838    
839     <pre caption="Setting up dhcpd">
840     # <i>emerge dhcp</i>
841     # <i>nano /etc/dhcp/dhcpd.conf</i>
842     <comment>(Here is a sample configuration file:)</comment>
843     authoritative;
844     ddns-update-style interim;
845     subnet 192.168.0.0 netmask 255.255.255.0 {
846     range 192.168.0.100 192.168.0.250;
847     default-lease-time 259200;
848     max-lease-time 518400;
849     option subnet-mask 255.255.255.0;
850     option broadcast-address 192.168.0.255;
851     option routers 192.168.0.1;
852     option domain-name-servers 192.168.0.1;
853     }
854     # <i>nano /etc/conf.d/dhcp</i>
855     <comment>(Set IFACE="eth0")</comment>
856     # <i>rc-update add dhcp default</i>
857     # <i>/etc/init.d/dhcp start</i>
858     </pre>
859    
860     <p>
861     This is the minimal setup required to replace the dnsmasq DHCP functionality
862     that we used earlier. Speaking of which, you did remember to disable the DHCP
863     features in dnsmasq didn't you? If not, you should do so now (just comment
864     out the <c>dhcp-range</c> setting in <path>/etc/dnsmasq.conf</path> and restart
865     the service).
866     </p>
867    
868     </body>
869     </section>
870    
871 vapier 1.38 <section>
872     <title>Connect Another LAN (or two or three or ...)</title>
873     <body>
874    
875     <p>
876     Sometimes you have need of connecting the router to another LAN. Maybe you
877     want to hook up a group of friends temporarily, or you're a neat freak and
878     want to section off different groups of computers, or you're just really
879     really bored. Whatever the reasons, extending the router to other LAN
880     networks should be pretty straightforward. In the following examples, I will
881     assume that this new network is connected via a third ethernet card, namely
882     <c>eth2</c>.
883     </p>
884    
885     <p>
886     First you need to configure the interface. Just take the instructions in the
887     <uri link="#doc_chap4_pre1">4.1 code listing</uri> and replace <c>eth0</c>
888     with <c>eth2</c> and <c>192.168.0</c> with <c>192.168.1</c>.
889     </p>
890    
891     <p>
892     Then you need to tweak dnsmasq to service the new interface. Just edit the
893     <path>/etc/conf.d/dnsmasq</path> file again and append <c>-i eth2</c> to
894     DNSMASQ_OPTS; using -i multiple times is OK. Then edit
895     <path>/etc/dnsmasq.conf</path> and add another line like the dhcp-range line
896     in the <uri link="#doc_chap5_pre1">5.1 code listing</uri>, replacing
897     <c>192.168.0</c> with <c>192.168.1</c>. Having multiple dhcp-range lines is
898     OK too.
899     </p>
900    
901     <p>
902     Finally, see the rules in the <uri link="#doc_chap5_pre2">5.2 code
903     listing</uri> and duplicate the rules that have <c>-i ${LAN}</c> in them. You
904     may want to create another variable, say <c>LAN2</c>, to make things easier.
905     </p>
906    
907     </body>
908     </section>
909    
910 vapier 1.4 </chapter>
911    
912     <chapter>
913 vapier 1.30 <title>Troubleshooting</title>
914 vapier 1.27
915     <section>
916     <title>Useful Tools</title>
917     <body>
918    
919     <p>
920     If you're having trouble getting your computers to communicate, you may way to
921     try out the following tools (they can all be found in the <c>net-analyzer</c>
922     portage category):
923     </p>
924    
925     <table>
926     <tr>
927     <th>Utility</th>
928     <th>Description</th>
929     </tr>
930     <tr>
931     <ti>ethereal</ti>
932     <ti>GUI tool to view all raw network data according to filters</ti>
933     </tr>
934     <tr>
935     <ti>tcpdump</ti>
936     <ti>Console tool to dump all raw network data according to filters</ti>
937     </tr>
938     <tr>
939     <ti>iptraf</ti>
940     <ti>ncurses based IP LAN monitor</ti>
941     </tr>
942     <tr>
943     <ti>ettercap</ti>
944     <ti>ncurses based network monitor/control</ti>
945     </tr>
946     </table>
947    
948     </body>
949     </section>
950    
951     <section>
952 vapier 1.31 <title>DHCP Fails To Start</title>
953     <body>
954    
955     <p>
956     When starting the dhcp init.d script for the first time, it may fail to load
957     but neglect to give you any useful info.
958     </p>
959    
960     <pre caption="DHCP Failing Example">
961     # <i>/etc/init.d/dhcp start</i>
962     * Setting ownership on dhcp.leases ... [ ok ]
963     * Starting dhcpd ... [ !! ]
964     </pre>
965    
966     <p>
967     The trick is to know where dhcpd is sending its output. Simply browse to
968     /var/log and read the log files. Since the exact log file depends on the
969     package you are using as a syslog, try running <c>grep -Rl dhcpd /var/log</c>
970     to narrow down the possibilities. Chances are you made a typo in your config
971     file. You could also try running <c>dhcpd -d -f</c> (short for debug /
972     foreground) and debug the error based upon the output.
973     </p>
974    
975     </body>
976     </section>
977    
978     <section>
979 vapier 1.27 <title>Incorrect MTU Value</title>
980     <body>
981    
982     <p>
983     If you experience odd errors (such as not being some webpages while others
984     load fine), you may be having Path MTU Discovery trouble. The quick way to
985     test is to run this iptables command:
986     </p>
987    
988     <pre caption="Circumvent MTU issues">
989     # <i>iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu</i>
990     </pre>
991    
992     <p>
993     This will affect all new connections, so just refresh the website you're
994     having problems with in order to test. In case it helps, the standard MTU
995     value for 100mbit ethernet connections is <c>1500</c> while for PPPoE
996     connections it is <c>1492</c>. For more info, you should read Chapter 15
997     of the <uri link="http://lartc.org/howto/">Linux Advanced Routing &amp;
998     Traffic Control HOWTO</uri>.
999     </p>
1000    
1001     </body>
1002     </section>
1003    
1004     </chapter>
1005    
1006     <chapter>
1007 vapier 1.4 <title>Final Notes</title>
1008 vapier 1.3 <section>
1009     <body>
1010 neysx 1.23
1011 vapier 1.3 <p>
1012 neysx 1.23 I have no final notes other than if you experience any troubles with the guide,
1013     please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with <uri
1014     link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If you have
1015     some interesting bits you think would enhance this guide, by all means send it
1016     my way for inclusion.
1017 vapier 1.3 </p>
1018 neysx 1.23
1019 vapier 1.1 </body>
1020     </section>
1021     </chapter>
1022     </guide>

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