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add some notes on adding more LANs

1 vapier 1.1 <?xml version='1.0' encoding='UTF-8'?>
2     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 vapier 1.38 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.37 2005/12/05 13:34:49 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 1.38 <version>1.23</version>
21     <date>2005-12-11</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     cards you have, try running <c>lspci</c>. You can get that from <c>emerge
108     pciutils</c>. Look for "Ethernet controller" in the output. Once you have
109     this information, go into your kernel and 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     In order for the following net.eth1 settings to work, you must have
203     baselayout-1.10.1 or later installed on your system.
204     </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/pppoe.conf</i>
210 neysx 1.23 <comment># Ethernet card connected to ADSL modem</comment>
211 vapier 1.1 ETH=eth1
212 neysx 1.23 <comment># ADSL user name.</comment>
213     USER=vla9h924
214 vapier 1.1 # <i>nano /etc/ppp/pap-secrets</i>
215 neysx 1.23 <comment># client server secret</comment>
216     "vla9h924" * "password"
217 vapier 1.1 # <i>nano /etc/conf.d/net</i>
218 vapier 1.25 <comment>Add an entry for config_eth1 and set it to adsl:</comment>
219     config_eth1=( "adsl" )
220 vapier 1.30 # <i>ln -s net.lo /etc/init.d/net.eth1</i>
221 vapier 1.1 # <i>rc-update add net.eth1 default</i>
222     # <i>/etc/init.d/net.eth1 start</i>
223     </pre>
224    
225 vapier 1.3 <warn>
226     When the DSL interface comes up, it will create ppp0. Although your NIC
227     is called eth1, the IP is actually bound to ppp0. From now on, when you
228     see examples that utilize 'eth1', substitute with 'ppp0'.
229     </warn>
230 vapier 1.1
231     </body>
232     </section>
233    
234     <section>
235     <title>Cable and/or dynamic/static IP</title>
236     <body>
237    
238     <p>
239 vapier 1.4 If you have a static IP then you will need a few more details than if
240 vapier 1.1 you have a dynamic IP. For static users, you will need your IP,
241     gateway, and DNS servers.
242     </p>
243    
244     <pre caption="Setting up eth1">
245     <comment>Dynamic IP Users:</comment>
246     # <i>emerge dhcpcd</i>
247     # <i>nano /etc/conf.d/net</i>
248 neysx 1.23 <comment>You'll need an entry like so:</comment>
249 vapier 1.25 config_eth1=( "dhcp" )
250 vapier 1.1
251     <comment>Static IP Users:</comment>
252     # <i>nano /etc/conf.d/net</i>
253 neysx 1.23 <comment>You'll need entries like so:</comment>
254 vapier 1.1 ifconfig_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" )
255 neysx 1.23 routes_eth1=( "default gw 66.92.78.1" )
256 vapier 1.1 # <i>nano /etc/resolv.conf</i>
257 neysx 1.23 <comment>Add one line per DNS server:</comment>
258     nameserver 123.123.123.123
259 vapier 1.1
260     <comment>Dynamic and Static Setup:</comment>
261 vapier 1.30 # <i>ln -s net.lo /etc/init.d/net.eth1</i>
262 vapier 1.1 # <i>rc-update add net.eth1 default</i>
263     # <i>/etc/init.d/net.eth1 start</i>
264     </pre>
265    
266     <p>
267     You should be all set to go now.
268     </p>
269    
270     </body>
271     </section>
272     </chapter>
273    
274     <chapter>
275     <title>Hug the LAN (bring along some friends)</title>
276     <section>
277     <body>
278    
279     <p>
280     This step is a breeze compared to the previous one.
281     </p>
282    
283     <pre caption="Setting up eth0">
284     # <i>nano /etc/conf.d/net</i>
285 neysx 1.23 <comment>Add a line like the following:</comment>
286     ifconfig_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )
287 vapier 1.1 # <i>rc-update add net.eth0 default</i>
288     # <i>/etc/init.d/net.eth0 start</i>
289     </pre>
290    
291     </body>
292     </section>
293     </chapter>
294    
295     <chapter>
296     <title>LAN Services (because we're nice people)</title>
297    
298     <section>
299     <title>DHCP Server</title>
300     <body>
301 neysx 1.23
302 vapier 1.1 <p>
303 neysx 1.23 I bet it'd be nice if everyone else in your house could just plug their
304     computers into the network and things would just work. No need to remember
305     mind-numbing details or make them stare at confusing configuration screens!
306     Life would be grand eh? Introducing the Dynamic Host Configuration Protocol
307     (DHCP) and why you should care.
308 vapier 1.1 </p>
309    
310 vapier 1.2 <p>
311     DHCP is exactly what its name implies. It's a protocol that allows you
312 neysx 1.23 to dynamically configure other hosts automatically. You run a DHCP server on
313 vapier 1.33 the router, give it all the information about your network (valid IPs,
314 neysx 1.23 DNS servers, gateways, etc...), and then when the other hosts start up, they
315     run a DHCP client to automatically configure themselves. No fuss, no muss!
316     For more information about DHCP, you can always visit <uri
317     link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
318 vapier 1.2 </p>
319    
320 vapier 1.33 <p>
321     We'll use a package called dnsmasq which provides both DHCP and DNS services.
322     For now lets just focus on the DHCP aspect. Note that if you want to run a
323     different DHCP server, you can find another example in the Fun Things chapter.
324     Also, if you wish to tinker with the DHCP server settings, just read the
325     comments in <path>/etc/dnsmasq.conf</path>. All the defaults should work fine
326     though.
327     </p>
328    
329     <pre caption="Setting up a DHCP server">
330     # <i>emerge dnsmasq</i>
331     # <i>nano /etc/dnsmasq.conf</i>
332     <comment>You should need to just add this one line:</comment>
333     dhcp-range=192.168.0.100,192.168.0.250,72h
334    
335     # <i>nano /etc/conf.d/dnsmasq</i>
336     <comment>Add "-i eth0" to DNSMASQ_OPTS</comment>
337     # <i>rc-update add dnsmasq default</i>
338     # <i>/etc/init.d/dnsmasq start</i>
339 vapier 1.1 </pre>
340    
341     <p>
342 neysx 1.23 Now your little router is a bona-fide DHCP server! Plugin those computers and
343     watch them work! With Windows systems you should go into the TCP/IP Properties
344     and select the 'Obtain an IP address automatically' and 'Obtain DNS server
345     address automatically' options. Sometimes the changes aren't instantaneous, so
346 vapier 1.31 you may have to open a command prompt and run <c>ipconfig /release</c> and
347 neysx 1.23 <c>ipconfig /renew</c>. But enough about Windows, let's get back to our
348     favorite penguin.
349 vapier 1.1 </p>
350 neysx 1.23
351 vapier 1.1 </body>
352     </section>
353    
354     <section>
355     <title>DNS Server</title>
356     <body>
357 neysx 1.23
358 vapier 1.2 <p>
359 neysx 1.23 When people want to visit a place on the internet, they remember names, not a
360 vapier 1.33 string of funky numbers. After all, what's easier to remember, ebay.com or
361 neysx 1.23 66.135.192.87? This is where the DNS steps in. DNS servers run all over the
362     internet, and whenever someone wants to visit 'ebay.com', these servers turn
363     'ebay.com' (what we understand) into '66.135.192.87' (what our computers
364     understand). For more information about DNS, you can always visit <uri
365     link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
366 vapier 1.2 </p>
367 vapier 1.1
368     <p>
369 vapier 1.33 Since we're using dnsmasq for our DHCP server, and it includes a DNS server,
370     you've got nothing left to do here! Your little router is already providing
371     DNS to its DHCP clients. Bet you wish everything was this easy ;).
372 vapier 1.1 </p>
373    
374     <p>
375 vapier 1.33 You're welcome to choose other DNS servers if you're more comfortable with
376     them, but the reason dnsmasq is great is because it was designed to do exactly
377     what we want and nothing more. It's a little DNS caching/forwarding server for
378     local networks. We're not looking to provide DNS for our own domain here, just
379     offer simple DNS services to everyone else on our LAN.
380 vapier 1.1 </p>
381    
382     </body>
383     </section>
384    
385     <section>
386 vapier 1.4 <title>NAT (a.k.a. IP-masquerading)</title>
387 vapier 1.1 <body>
388    
389     <p>
390 neysx 1.23 At this point, people on your network can talk to each other and they can look
391     up hostnames via DNS, but they still can't actually connect to the internet.
392     While you may think that's great (more bandwidth for you!), I bet they're not
393     too happy just yet.
394 vapier 1.1 </p>
395    
396 vapier 1.2 <p>
397 vapier 1.33 This is where Network Address Translation (NAT) steps in. NAT is a way of
398     connecting multiple computers in a private LAN to the internet when you have a
399     smaller number of public IP addresses available to you. Typically you are given
400     1 IP by your ISP, but you want to let your whole house connect to the internet.
401     NAT is the magic that makes this possible. For more information about NAT, you
402     can always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
403 vapier 1.2 </p>
404    
405     <note>
406 neysx 1.23 Before we get started, make sure you have iptables on your system. Although it
407     is automatically installed on most systems, you may not have it. If you don't,
408     just run <c>emerge iptables</c>.
409 vapier 1.2 </note>
410    
411 vapier 1.1 <pre caption="Setting up iptables">
412     <comment>First we flush our current rules</comment>
413     # <i>iptables -F</i>
414     # <i>iptables -t nat -F</i>
415    
416 vapier 1.33 <comment>Setup default policies to handle unmatched traffic</comment>
417 vapier 1.32 # <i>iptables -P INPUT ACCEPT</i>
418     # <i>iptables -P OUTPUT ACCEPT</i>
419     # <i>iptables -P FORWARD DROP</i>
420    
421 vapier 1.30 <comment>Copy and paste these examples ...</comment>
422     # <i>export LAN=eth0</i>
423     # <i>export WAN=eth1</i>
424    
425 vapier 1.1 <comment>Then we lock our services so they only work from the LAN</comment>
426 vapier 1.30 # <i>iptables -I INPUT 1 -i ${LAN} -j ACCEPT</i>
427 vapier 1.1 # <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
428 vapier 1.30 # <i>iptables -A INPUT -p UDP --dport bootps -i ! ${LAN} -j REJECT</i>
429     # <i>iptables -A INPUT -p UDP --dport domain -i ! ${LAN} -j REJECT</i>
430 vapier 1.1
431 vapier 1.21 <comment>(Optional) Allow access to our ssh server from the WAN</comment>
432 vapier 1.30 # <i>iptables -A INPUT -p TCP --dport ssh -i ${WAN} -j ACCEPT</i>
433 vapier 1.21
434 vapier 1.1 <comment>Drop TCP / UDP packets to privileged ports</comment>
435 vapier 1.30 # <i>iptables -A INPUT -p TCP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
436     # <i>iptables -A INPUT -p UDP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
437 vapier 1.1
438     <comment>Finally we add the rules for NAT</comment>
439 vapier 1.30 # <i>iptables -I FORWARD -i ${LAN} -d 192.168.0.0/255.255.0.0 -j DROP</i>
440     # <i>iptables -A FORWARD -i ${LAN} -s 192.168.0.0/255.255.0.0 -j ACCEPT</i>
441     # <i>iptables -A FORWARD -i ${WAN} -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
442     # <i>iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE</i>
443 vapier 1.1 <comment>Tell the kernel that ip forwarding is OK</comment>
444     # <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i>
445     # <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
446    
447     <comment>This is so when we boot we don't have to run the rules by hand</comment>
448     # <i>/etc/init.d/iptables save</i>
449     # <i>rc-update add iptables default</i>
450 vapier 1.14 # <i>nano /etc/sysctl.conf</i>
451     <comment>Add/Uncomment the following lines:
452     net.ipv4.ip_forward = 1
453     net.ipv4.conf.default.rp_filter = 1</comment>
454 vapier 1.1 </pre>
455    
456     <p>
457 neysx 1.23 Once you've typed out all of that, the rest of your network should now be able
458     to use the internet as if they were directly connected themselves.
459 vapier 1.1 </p>
460    
461 vapier 1.3 </body>
462     </section>
463     </chapter>
464    
465     <chapter>
466     <title>Fun Things (for a rainy day)</title>
467    
468     <section>
469     <title>Intro</title>
470     <body>
471 neysx 1.23
472 vapier 1.1 <p>
473 neysx 1.23 Believe it or not, you're done :). From here on out, I'll cover a bunch of
474     common topics that may interest you. Everything in this chapter is completely
475     optional.
476 vapier 1.1 </p>
477 neysx 1.23
478 vapier 1.3 </body>
479     </section>
480 vapier 1.1
481 vapier 1.3 <section>
482     <title>Port Forwarding</title>
483     <body>
484 neysx 1.23
485 vapier 1.3 <p>
486 neysx 1.23 Sometimes you would like to be able to host services on a computer behind the
487     router, or just to make your life easier when connecting remotely. Perhaps you
488     want to run a FTP, HTTP, SSH, or VNC server on one or more machines behind your
489     router and be able to connect to them all. The only caveat is that you can
490     only have one service/machine combo per port. For example, there is no
491     practical way to setup three FTP servers behind your router and then try to
492     connect to them all through port 21; only one can be on port 21 while the
493     others would have to be on say port 123 and port 567.
494 vapier 1.3 </p>
495    
496     <p>
497 neysx 1.23 All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING
498 vapier 1.30 [-p protocol] --dport [external port on router] -i ${WAN} -j DNAT --to [ip/port
499 vapier 1.33 to forward to]</c>. Unfortunately, iptables does not accept hostnames when port
500     forwarding. If you are forwarding an external port to the same port on the
501     internal machine, you can omit the destination port. See the iptables(8) man
502     page for more information.
503 vapier 1.3 </p>
504    
505 swift 1.28 <pre caption="Running the iptables commands">
506 vapier 1.30 <comment>Copy and paste these examples ...</comment>
507     # <i>export LAN=eth0</i>
508     # <i>export WAN=eth1</i>
509    
510 vapier 1.3 <comment>Forward port 2 to ssh on an internal host</comment>
511 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i ${WAN} -j DNAT --to 192.168.0.2:22</i>
512 vapier 1.3
513     <comment>FTP forwarding to an internal host</comment>
514 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i ${WAN} -j DNAT --to 192.168.0.56</i>
515 vapier 1.3
516     <comment>HTTP forwarding to an internal host</comment>
517 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i ${WAN} -j DNAT --to 192.168.0.56</i>
518 vapier 1.3
519     <comment>VNC forwarding for internal hosts</comment>
520 vapier 1.30 # <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i ${WAN} -j DNAT --to 192.168.0.2</i>
521     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i ${WAN} -j DNAT --to 192.168.0.3:5900</i>
522 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>
523    
524     <comment>Bittorrent forwarding</comment>
525 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i ${WAN} -j DNAT --to 192.168.0.2</i>
526 vapier 1.15
527 vapier 1.33 <comment>eDonkey/eMule forwarding</comment>
528     # <i>iptables -t nat -A PREROUTING -p tcp --dport 4662 -i ${WAN} -j DNAT --to 192.168.0.55</i>
529    
530 vapier 1.15 <comment>Game Cube Warp Pipe support</comment>
531 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i ${WAN} -j DNAT --to 192.168.0.56</i>
532 vapier 1.15
533 vapier 1.33 <comment>Playstation 2 Online support</comment>
534 vapier 1.30 # <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
535     # <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
536 vapier 1.34
537     <comment>Xbox Live</comment>
538     # <i>iptables -t nat -A PREROUTING -p tcp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
539     # <i>iptables -t nat -A PREROUTING -p udp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
540     # <i>iptables -t nat -A PREROUTING -p udp --dport 88 -i ${WAN} -j DNAT --to 192.168.0.69</i>
541 vapier 1.3 </pre>
542    
543     <note>
544 neysx 1.37 If you have other common / cool examples, please <mail
545     link="vapier@gentoo.org">e-mail me</mail>.
546 vapier 1.3 </note>
547 neysx 1.23
548 vapier 1.3 </body>
549     </section>
550    
551     <section>
552     <title>Identd (for IRC)</title>
553     <body>
554 neysx 1.23
555 vapier 1.3 <p>
556 neysx 1.23 Internet Relay Chat utilizes the ident service pretty heavily. Now that the
557     IRC clients are behind the router, we need a way to host ident for both the
558     router and the clients. One such server has been created called
559     <c>midentd</c>.
560 vapier 1.3 </p>
561    
562     <pre caption="Setting up ident">
563     # <i>emerge midentd</i>
564     # <i>rc-update add midentd default</i>
565     # <i>/etc/init.d/midentd start</i>
566     </pre>
567    
568     <p>
569 neysx 1.23 There are a few other ident servers in portage. Depending on your needs, I
570     would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
571 vapier 1.3 </p>
572 neysx 1.23
573 vapier 1.3 </body>
574     </section>
575    
576 vapier 1.5 <!--
577     <section>
578     <title>Traffic Shaping</title>
579     <body>
580     <p>
581     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>
582     found over at the TLDP. Feel free to refer to the original document
583     for more details.
584     </p>
585    
586     <p>
587     Here we will be setting up what some people refer to as a "Packet Shaper",
588     <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
589     or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
590     Simply put, we want to setup rules on our router that will slow down
591     certain activities (like sending large e-mails or downloading from P2P
592     networks) while keeping other activities (like browsing the web or playing
593     online video games) reasonably fast. A 30 second difference in a video
594     game is a lot worse than a 30 second difference in downloading large
595     files :).
596     </p>
597    
598     <p>
599     The first thing is to make sure your kernel has all the features added to
600     it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
601     information. Next, you will need to <c>emerge iptables iputils</c> so that
602     you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
603     commands.
604     </p>
605    
606     <p>
607     Before we jump into the commands, let's cover a little of the theory. The
608     way this whole system works is to classify common network streams and then
609     to prioritize them. You use iptables to classify network streams, iputils
610     to define the different priority levels, and the kernel to adjust speeds.
611     Just remember that although you can control outbound traffic pretty tightly
612     (from the LAN to the WAN), your ability to control inbound traffic (from
613     the WAN to the LAN) is somewhat limited. Just remember that the following
614     examples are to get your feet wet; if you want more then I'd suggest
615     reading up on the subject. In this example, we will be using the
616     <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
617     packet scheduling algorithm. Still with me? Great, let's start shaping :).
618     </p>
619    
620     <pre caption="Setup">
621     DEV=eth1 <comment>NIC connected to WAN</comment>
622     RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
623     RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
624    
625     <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
626     ip link set dev ${DEV} qlen 30
627     tc qdisc add dev ${DEV} root handle 1: htb default 45
628     tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
629     </pre>
630    
631     <p>
632     Here we initialized the system which will be used to prioritize all of
633     our network traffic. We created our queue, told it to use the HTB
634     algorithm, and set the default classification level to '45'. The
635     default is completely arbitrary, as are the levels we choose from
636     here on out. The only thing that matters is how the levels compare
637     relatively; a level '10' packet will be given preference over a
638     level '45' packet. Let's move on to declaring different levels.
639     </p>
640    
641     <pre caption="Declaring levels">
642     tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
643     tc qdisc add dev $DEV parent 1:10 handle 10: sfq
644     </pre>
645     </body>
646     </section>
647     -->
648    
649 vapier 1.3 <section>
650 vapier 1.9 <title>Time Server</title>
651     <body>
652 neysx 1.23
653 vapier 1.9 <p>
654 vapier 1.24 Keeping your system time correct is essential in maintaining a healthy system.
655 neysx 1.23 One of the most common ways of accomplishing this is with the Network Time
656     Protocol (NTP) and the ntp package (which provides implementations for both
657     server and client).
658 vapier 1.9 </p>
659    
660     <p>
661 neysx 1.23 Many people run ntp clients on their computers. Obviously, the more clients in
662     the world, the larger the load the ntp servers need to shoulder. In
663     environments like home networks though, we can help keep the load down on
664     public servers while still providing the proper time to all our computers. As
665     an added bonus, our private updates will be a lot faster for the clients too!
666     All we have to do is run a ntp server on our router that synchronizes itself
667     with the public internet servers while providing the time to the rest of the
668     computers in the network. To get started, simply <c>emerge ntp</c> on the
669 vapier 1.9 router.
670     </p>
671    
672     <pre caption="Setting up the NTP server">
673     # <i>nano /etc/conf.d/ntp-client</i>
674     <comment>Customize if you wish but the defaults should be fine</comment>
675     # <i>rc-update add ntp-client default</i>
676    
677     # <i>nano /etc/ntp.conf</i>
678 neysx 1.23 <comment>Add the follwing lines:</comment>
679 vapier 1.9 restrict default ignore
680     restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
681 neysx 1.23 <comment>These will allow only ntp clients with an IP
682     address in the 192.168.0.xxx range to use your ntp server</comment>
683 vapier 1.9 # <i>nano /etc/conf.d/ntpd</i>
684     <comment>Customize if you wish but the defaults should be fine</comment>
685 vapier 1.17 # <i>rc-update add ntpd default</i>
686 vapier 1.9
687     # <i>/etc/init.d/ntp-client start</i>
688     # <i>/etc/init.d/ntpd start</i>
689     </pre>
690    
691 vapier 1.22 <note>
692 neysx 1.23 You should make sure that you allow inbound and outbound communication on the
693     ntp port (123/udp) when setting up the server. The client just needs outbound
694     access on port 123 over udp.
695 vapier 1.22 </note>
696    
697 vapier 1.9 <p>
698 neysx 1.23 Now, on your clients, have them <c>emerge ntp</c> also. However, we will just
699     run the ntp client so setup is a lot simpler.
700 vapier 1.9 </p>
701    
702     <pre caption="Setting up a NTP client">
703     # <i>nano /etc/conf.d/ntp-client</i>
704     <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
705     # <i>rc-update add ntp-client default</i>
706     # <i>/etc/init.d/ntp-client start</i>
707     </pre>
708 neysx 1.23
709 vapier 1.9 </body>
710     </section>
711    
712     <section>
713 vapier 1.29 <title>Rsync Server</title>
714     <body>
715    
716     <p>
717     For those who run multiple Gentoo boxes on the same lan, you often want to
718     keep from having every machine running <c>emerge sync</c> with remote
719     servers. By setting up a local rsync, you save on both your bandwidth and
720     the Gentoo rsync servers' bandwidth. It's pretty simple to do.
721     </p>
722     <note>
723     For a much more in-depth rsync guide, please see the official <uri
724     link="/doc/en/rsync.xml#doc_chap4">rsync guide</uri>
725     </note>
726    
727     <p>
728     Since every Gentoo machine requires rsync, theres no need to emerge it. Edit
729     the default <path>/etc/rsyncd.conf</path> config file, uncomment the
730     <c>[gentoo-portage]</c> section, and make sure you add an <c>address</c>
731     option. All the other defaults should be fine.
732     </p>
733    
734     <pre caption="Rsync server config">
735     pid file = /var/run/rsyncd.pid
736     use chroot = yes
737     read only = yes
738     address = 192.168.0.1
739    
740     [gentoo-portage]
741     path = /mnt/space/portage
742     comment = Gentoo Linux Portage tree
743     exclude = /distfiles /packages
744     </pre>
745    
746     <p>
747     Then you need to start the service (again, the defaults are OK).
748     </p>
749    
750     <pre caption="Starting the rsync server">
751     # <i>/etc/init.d/rsyncd start</i>
752     # <i>rc-update add rsyncd default</i>
753     </pre>
754    
755     <p>
756     Only thing left is to set tell your clients to sync against the router.
757     </p>
758    
759     <pre caption="Client SYNC settings in make.conf">
760     SYNC="rsync://192.168.0.1/gentoo-portage"
761     </pre>
762    
763     </body>
764     </section>
765    
766     <section>
767 vapier 1.3 <title>Mail Server</title>
768     <body>
769 neysx 1.23
770 vapier 1.3 <p>
771 neysx 1.23 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP) server
772     on the router. You may have your own reason for wanting to do so, but I run it
773     so that the users see mail as being sent instantly and the work of
774     retrying/routing is left up to the mail server. Some ISPs also don't allow for
775     mail relaying for accounts that aren't part of their network (like Verizon).
776     Also, you can easily throttle the delivery of mail so that large attachments
777     won't seriously lag your connection for half an hour.
778 vapier 1.4 </p>
779    
780     <pre caption="Setting up SMTP">
781     # <i>emerge qmail</i>
782     <comment>make sure the output of `hostname` is correct</comment>
783     # <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
784 vapier 1.30 # <i>iptables -I INPUT -p tcp --dport smtp -i ! ${LAN} -j REJECT</i>
785 vapier 1.4 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
786 vapier 1.10 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
787 vapier 1.13 <!--
788 vapier 1.4 # <i>cd /etc/tcprules.d</i>
789     # <i>nano tcp.qmail-smtp</i>
790 vapier 1.13 -->
791     # <i>cd /etc</i>
792     # <i>nano tcp.smtp</i>
793 neysx 1.23 <comment>Add an entry like so to the allow section:</comment>
794     192.168.0.:allow,RELAYCLIENT=""
795 vapier 1.13 <!--
796 vapier 1.4 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
797 vapier 1.13 -->
798     # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
799 vapier 1.4 # <i>rc-update add svscan default</i>
800     # <i>/etc/init.d/svscan start</i>
801     </pre>
802    
803     <p>
804 neysx 1.23 I'm a huge fan of qmail, but you're free to use a different mta :). When you
805     setup e-mail on the hosts in your network, tell them that their SMTP server is
806     192.168.0.1 and everything should be peachy. You might want to visit the <uri
807     link="http://qmail.org/">qmail homepage</uri> for more documentation.
808 vapier 1.3 </p>
809 neysx 1.23
810 vapier 1.3 </body>
811     </section>
812    
813 vapier 1.4 <!--
814 vapier 1.3 <section>
815 vapier 1.4 <title>E-mail Virus Scanning</title>
816 vapier 1.3 <body>
817     <p>
818 vapier 1.4 If you'd like to provide e-mail virus scanning for your users, but
819     don't want to have to install a virus scanner on every single machine,
820     then <c>pop3vscan</c> may just be the thing for you; a transparent
821     Post Office Protocol (POP) scanner.
822 vapier 1.3 </p>
823 vapier 1.4
824     <pre caption="Setting up pop3vscan">
825     TODO
826     </pre>
827    
828 vapier 1.3 </body>
829     </section>
830 vapier 1.4 -->
831 vapier 1.3
832 vapier 1.33 <section>
833     <title>Full DHCP Server</title>
834     <body>
835    
836     <p>
837     Earlier we used dnsmasq to provide DHCP service to all our clients. For most
838     people with a simple small LAN, this is perfect. But you may need something
839     with more features. Thus we turn to a full-featured DHCP server as provided
840     by the <uri link="http://www.isc.org/products/DHCP">ISC</uri> folks.
841     </p>
842    
843     <pre caption="Setting up dhcpd">
844     # <i>emerge dhcp</i>
845     # <i>nano /etc/dhcp/dhcpd.conf</i>
846     <comment>(Here is a sample configuration file:)</comment>
847     authoritative;
848     ddns-update-style interim;
849     subnet 192.168.0.0 netmask 255.255.255.0 {
850     range 192.168.0.100 192.168.0.250;
851     default-lease-time 259200;
852     max-lease-time 518400;
853     option subnet-mask 255.255.255.0;
854     option broadcast-address 192.168.0.255;
855     option routers 192.168.0.1;
856     option domain-name-servers 192.168.0.1;
857     }
858     # <i>nano /etc/conf.d/dhcp</i>
859     <comment>(Set IFACE="eth0")</comment>
860     # <i>rc-update add dhcp default</i>
861     # <i>/etc/init.d/dhcp start</i>
862     </pre>
863    
864     <p>
865     This is the minimal setup required to replace the dnsmasq DHCP functionality
866     that we used earlier. Speaking of which, you did remember to disable the DHCP
867     features in dnsmasq didn't you? If not, you should do so now (just comment
868     out the <c>dhcp-range</c> setting in <path>/etc/dnsmasq.conf</path> and restart
869     the service).
870     </p>
871    
872     </body>
873     </section>
874    
875 vapier 1.38 <section>
876     <title>Connect Another LAN (or two or three or ...)</title>
877     <body>
878    
879     <p>
880     Sometimes you have need of connecting the router to another LAN. Maybe you
881     want to hook up a group of friends temporarily, or you're a neat freak and
882     want to section off different groups of computers, or you're just really
883     really bored. Whatever the reasons, extending the router to other LAN
884     networks should be pretty straightforward. In the following examples, I will
885     assume that this new network is connected via a third ethernet card, namely
886     <c>eth2</c>.
887     </p>
888    
889     <p>
890     First you need to configure the interface. Just take the instructions in the
891     <uri link="#doc_chap4_pre1">4.1 code listing</uri> and replace <c>eth0</c>
892     with <c>eth2</c> and <c>192.168.0</c> with <c>192.168.1</c>.
893     </p>
894    
895     <p>
896     Then you need to tweak dnsmasq to service the new interface. Just edit the
897     <path>/etc/conf.d/dnsmasq</path> file again and append <c>-i eth2</c> to
898     DNSMASQ_OPTS; using -i multiple times is OK. Then edit
899     <path>/etc/dnsmasq.conf</path> and add another line like the dhcp-range line
900     in the <uri link="#doc_chap5_pre1">5.1 code listing</uri>, replacing
901     <c>192.168.0</c> with <c>192.168.1</c>. Having multiple dhcp-range lines is
902     OK too.
903     </p>
904    
905     <p>
906     Finally, see the rules in the <uri link="#doc_chap5_pre2">5.2 code
907     listing</uri> and duplicate the rules that have <c>-i ${LAN}</c> in them. You
908     may want to create another variable, say <c>LAN2</c>, to make things easier.
909     </p>
910    
911     </body>
912     </section>
913    
914 vapier 1.4 </chapter>
915    
916     <chapter>
917 vapier 1.30 <title>Troubleshooting</title>
918 vapier 1.27
919     <section>
920     <title>Useful Tools</title>
921     <body>
922    
923     <p>
924     If you're having trouble getting your computers to communicate, you may way to
925     try out the following tools (they can all be found in the <c>net-analyzer</c>
926     portage category):
927     </p>
928    
929     <table>
930     <tr>
931     <th>Utility</th>
932     <th>Description</th>
933     </tr>
934     <tr>
935     <ti>ethereal</ti>
936     <ti>GUI tool to view all raw network data according to filters</ti>
937     </tr>
938     <tr>
939     <ti>tcpdump</ti>
940     <ti>Console tool to dump all raw network data according to filters</ti>
941     </tr>
942     <tr>
943     <ti>iptraf</ti>
944     <ti>ncurses based IP LAN monitor</ti>
945     </tr>
946     <tr>
947     <ti>ettercap</ti>
948     <ti>ncurses based network monitor/control</ti>
949     </tr>
950     </table>
951    
952     </body>
953     </section>
954    
955     <section>
956 vapier 1.31 <title>DHCP Fails To Start</title>
957     <body>
958    
959     <p>
960     When starting the dhcp init.d script for the first time, it may fail to load
961     but neglect to give you any useful info.
962     </p>
963    
964     <pre caption="DHCP Failing Example">
965     # <i>/etc/init.d/dhcp start</i>
966     * Setting ownership on dhcp.leases ... [ ok ]
967     * Starting dhcpd ... [ !! ]
968     </pre>
969    
970     <p>
971     The trick is to know where dhcpd is sending its output. Simply browse to
972     /var/log and read the log files. Since the exact log file depends on the
973     package you are using as a syslog, try running <c>grep -Rl dhcpd /var/log</c>
974     to narrow down the possibilities. Chances are you made a typo in your config
975     file. You could also try running <c>dhcpd -d -f</c> (short for debug /
976     foreground) and debug the error based upon the output.
977     </p>
978    
979     </body>
980     </section>
981    
982     <section>
983 vapier 1.27 <title>Incorrect MTU Value</title>
984     <body>
985    
986     <p>
987     If you experience odd errors (such as not being some webpages while others
988     load fine), you may be having Path MTU Discovery trouble. The quick way to
989     test is to run this iptables command:
990     </p>
991    
992     <pre caption="Circumvent MTU issues">
993     # <i>iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu</i>
994     </pre>
995    
996     <p>
997     This will affect all new connections, so just refresh the website you're
998     having problems with in order to test. In case it helps, the standard MTU
999     value for 100mbit ethernet connections is <c>1500</c> while for PPPoE
1000     connections it is <c>1492</c>. For more info, you should read Chapter 15
1001     of the <uri link="http://lartc.org/howto/">Linux Advanced Routing &amp;
1002     Traffic Control HOWTO</uri>.
1003     </p>
1004    
1005     </body>
1006     </section>
1007    
1008     </chapter>
1009    
1010     <chapter>
1011 vapier 1.4 <title>Final Notes</title>
1012 vapier 1.3 <section>
1013     <body>
1014 neysx 1.23
1015 vapier 1.3 <p>
1016 neysx 1.23 I have no final notes other than if you experience any troubles with the guide,
1017     please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with <uri
1018     link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If you have
1019     some interesting bits you think would enhance this guide, by all means send it
1020     my way for inclusion.
1021 vapier 1.3 </p>
1022 neysx 1.23
1023 vapier 1.1 </body>
1024     </section>
1025     </chapter>
1026     </guide>

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