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1 vapier 1.1 <?xml version='1.0' encoding='UTF-8'?>
2 vapier 1.20 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.19 2004/08/13 15:14:03 vapier Exp $ -->
3 vapier 1.1 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4    
5     <guide link="/doc/en/home-router-howto.xml">
6    
7     <title>Home Router Guide</title>
8    
9     <author title="Author">
10     <mail link="vapier@gentoo.org">Mike Frysinger</mail>
11     </author>
12    
13     <abstract>
14     This document details how to turn an old Gentoo machine into a router
15     for connecting your home network to the internet.
16     </abstract>
17    
18     <version>1.1</version>
19     <date>July 21, 2004</date>
20    
21     <chapter>
22     <title>Introduction</title>
23     <section>
24     <body>
25    
26     <p>
27     Building your own router out of old spare parts has many advantages
28     over buying a pre-made canned router by say Linksys. The biggest one by
29     far is control over the connection. The other advantages are left up to
30     your imagination; just about anything can be done in this scenario,
31     it's just a matter of needing it.
32     </p>
33    
34     <p>
35     This guide will show you how to setup Network Address Translation (NAT)
36     on the router (kernel and iptables), add and configure common services
37 vapier 1.2 (Domain Name System (DNS) via dnsmasq, dhcp via dhcpcd, ADSL via
38     rp-pppoe), and conclude with more elaborate and fun things that can be
39 vapier 1.3 done (port forwarding, traffic shaping, proxies/caching, etc...).
40 vapier 1.1 </p>
41    
42     <p>
43     Before getting started, there's a few basic requirements you must meet.
44     First, you'll need a computer that has at least 2 Network Interface
45     Cards (NICs) in it. Next, you'll need the configuration settings for
46     your internet connection (may include things like
47     IP/DNS/Gateway/username/password). Finally, you'll need a bit of spare
48     time and some Gentoo loving.
49     </p>
50    
51     <p>
52     The conventions used in this guide are:
53     </p>
54     <ul>
55     <li>eth0 - NIC connected to the Local Area Network (LAN)</li>
56     <li>eth1 - NIC connected to the Wide Area Network (WAN)</li>
57     <li>LAN utilizes the private 192.168.0.xxx network</li>
58     <li>router is hardcoded to the standard 192.168.0.1 IP</li>
59 vapier 1.3 <li>router is running Linux 2.4 or 2.6; you're on your own with 2.0/2.2</li>
60 vapier 1.1 </ul>
61    
62     <impo>
63     Due to security precautions, I would highly suggest you shut down any
64     unneeded services on the router until we have a chance to get the
65     firewall up and rolling. To view the currently running services, just
66     run <c>rc-status</c>.
67     </impo>
68    
69     </body>
70     </section>
71     </chapter>
72    
73     <chapter>
74     <title>Kernel setup (know thyself first)</title>
75     <section>
76     <body>
77    
78     <p>
79     Your kernel needs to have the drivers running for both your NICs. To
80     see if your cards are already setup, just run <c>ifconfig</c>. Your
81     output may differ slightly from the following, that's fine. What
82     matters is that the interface shows up at all.
83     </p>
84     <pre caption="Checking NICs">
85     # <i>ifconfig -a</i>
86     eth0 Link encap:Ethernet HWaddr 00:60:F5:07:07:B8
87     BROADCAST MULTICAST MTU:1500 Metric:1
88     RX packets:0 errors:0 dropped:0 overruns:0 frame:0
89     TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
90     collisions:0 txqueuelen:1000
91     RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
92     Interrupt:11 Base address:0x9800
93    
94     eth1 Link encap:Ethernet HWaddr 00:60:F5:07:07:B9
95     BROADCAST MULTICAST MTU:1500 Metric:1
96     RX packets:0 errors:0 dropped:0 overruns:0 frame:0
97     TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
98     collisions:0 txqueuelen:1000
99     RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
100     Interrupt:10 Base address:0x9400
101     </pre>
102     <p>
103     If you do not see your two cards showing up and you're not sure what
104     kind of cards you have, try running <c>lspci</c>. You can get that from
105 vapier 1.4 <c>emerge pciutils</c>. Look for "Ethernet controller" in the output.
106     Once you have this information, go into your kernel and add support for
107     the correct drivers.
108 vapier 1.1 </p>
109    
110     <p>
111     The next thing you'll need is support for iptables and NAT (and packet
112     shaping if you want). The following list is split up into required
113     (*), suggested (x), and shaper (s) features. It does not matter whether
114     you build the features into the kernel or as a module so long as when
115 vapier 1.4 the feature is needed, the correct module(s) are loaded (module loading
116 vapier 1.1 is left to the reader as a fun exercise however).
117     </p>
118     <pre caption="Network Options">
119     <i>Networking options ---&gt;</i>
120     <i> [*] TCP/IP networking</i>
121     <i> [*] IP: advanced router</i>
122     <i> [*] Network packet filtering (replaces ipchains)</i>
123 vapier 1.20 <comment>If you use 2.4.x, you have to enable the following for DHCP:</comment>
124     <i> [*] Socket Filtering</i>
125 vapier 1.1
126     <i> IP: Netfilter Configuration ---&gt;</i>
127     <i> [*] Connection tracking (required for masq/NAT)</i>
128     <i> [x] FTP protocol support</i>
129     <i> [x] IRC protocol support</i>
130     <i> [*] IP tables support (required for filtering/masq/NAT)</i>
131     <i> [*] IP range match support</i>
132     <i> [x] MAC address match support</i>
133     <i> [*] Multiple port match support</i>
134     <i> [*] Packet filtering</i>
135     <i> [*] REJECT target support</i>
136     <i> [x] REDIRECT target support</i>
137     <i> [*] Full NAT</i>
138     <i> [*] MASQUERADE target support</i>
139     <i> [s] Packet mangling</i>
140     <i> [s] MARK target support</i>
141     <i> [x] LOG target support</i>
142    
143     <i> QoS and/or fair queueing ---&gt;</i>
144     <i> [s] QoS and/or fair queueing</i>
145     <i> [s] HTB packet scheduler</i>
146     <i> [s] Ingress Qdisc</i>
147     </pre>
148     <note>
149     Somethings may be slightly different in a 2.4 vs 2.6 kernel, but you
150 vapier 1.3 should be able to figure it out :).
151 vapier 1.1 </note>
152    
153     </body>
154     </section>
155     </chapter>
156    
157     <chapter>
158     <title>Hug the WAN (a.k.a. The Internet)</title>
159    
160     <section>
161     <title>Intro</title>
162     <body>
163     <p>
164     There are many ways to connect to the internet so I'll just cover the
165     ones I'm familiar with. That leaves us with ADSL (PPPoE) and cable
166     modems (static/dynamic). If there are other methods out there, feel
167     free to write up a little blurb and e-mail me. Feel free to skip any of
168     the following sections in this chapter that don't apply to you. This
169     chapter is just about getting the router connected to the internet via
170     eth1.
171     </p>
172     </body>
173     </section>
174    
175     <section>
176     <title>ADSL and PPPoE</title>
177     <body>
178    
179     <p>
180     All the fancy PPPoE software has been bundled up into one little nice
181     package nowadays called <uri link="http://www.roaringpenguin.com/">Roaring Penguin</uri>.
182     Simply <c>emerge rp-pppoe</c> and you'll be on your way. Remember how
183     I said you'll need username/password information? Well I wasn't lying
184     so I hope you have it now! Load up <path>/etc/ppp/pppoe.conf</path> in
185     your favorite editor and set it up.
186     </p>
187    
188 vapier 1.8 <note>
189     In order for the following net.eth1 settings to work, you must have
190     baselayout-1.10.1 or later installed on your system.
191     </note>
192    
193 vapier 1.1 <pre caption="Setting up eth1">
194     <comment>(Replace 'vla9h924' with your username and 'password' with your password)</comment>
195    
196     # <i>nano /etc/ppp/pppoe.conf</i>
197     <comment># Ethernet card connected to ADSL modem
198     ETH=eth1
199     # ADSL user name.
200     USER=vla9h924</comment>
201     # <i>nano /etc/ppp/pap-secrets</i>
202     <comment># client server secret
203     "vla9h924" * "password"</comment>
204     # <i>nano /etc/conf.d/net</i>
205     <comment>Add an entry for ifconfig_eth1 and set it to adsl:
206     ifconfig_eth1=( "adsl" )</comment>
207     # <i>ln -s net.eth0 /etc/init.d/net.eth1</i>
208     # <i>rc-update add net.eth1 default</i>
209     # <i>/etc/init.d/net.eth1 start</i>
210     </pre>
211    
212 vapier 1.3 <warn>
213     When the DSL interface comes up, it will create ppp0. Although your NIC
214     is called eth1, the IP is actually bound to ppp0. From now on, when you
215     see examples that utilize 'eth1', substitute with 'ppp0'.
216     </warn>
217 vapier 1.1
218     </body>
219     </section>
220    
221     <section>
222     <title>Cable and/or dynamic/static IP</title>
223     <body>
224    
225     <p>
226 vapier 1.4 If you have a static IP then you will need a few more details than if
227 vapier 1.1 you have a dynamic IP. For static users, you will need your IP,
228     gateway, and DNS servers.
229     </p>
230    
231     <pre caption="Setting up eth1">
232     <comment>Dynamic IP Users:</comment>
233     # <i>emerge dhcpcd</i>
234     # <i>nano /etc/conf.d/net</i>
235     <comment>You'll need an entry like so:
236     ifconfig_eth1=( "dhcp" )</comment>
237    
238     <comment>Static IP Users:</comment>
239     # <i>nano /etc/conf.d/net</i>
240     <comment>You'll need entries like so:
241     ifconfig_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" )
242     routes_eth1=( "default gw 66.92.78.1" )</comment>
243     # <i>nano /etc/resolv.conf</i>
244     <comment>Add one line per DNS server:
245     nameserver 123.123.123.123</comment>
246    
247     <comment>Dynamic and Static Setup:</comment>
248     # <i>ln -s net.eth0 /etc/init.d/net.eth1</i>
249     # <i>rc-update add net.eth1 default</i>
250     # <i>/etc/init.d/net.eth1 start</i>
251     </pre>
252    
253     <p>
254     You should be all set to go now.
255     </p>
256    
257     </body>
258     </section>
259     </chapter>
260    
261     <chapter>
262     <title>Hug the LAN (bring along some friends)</title>
263     <section>
264     <body>
265    
266     <p>
267     This step is a breeze compared to the previous one.
268     </p>
269    
270     <pre caption="Setting up eth0">
271     # <i>nano /etc/conf.d/net</i>
272     <comment>Add a line like the following:
273     ifconfig_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )</comment>
274     # <i>rc-update add net.eth0 default</i>
275     # <i>/etc/init.d/net.eth0 start</i>
276     </pre>
277    
278     </body>
279     </section>
280     </chapter>
281    
282     <chapter>
283     <title>LAN Services (because we're nice people)</title>
284    
285     <section>
286     <title>DHCP Server</title>
287     <body>
288     <p>
289     I bet it'd be nice if everyone else in your house could just plug
290     their computers into the network and things would just work. No need to
291     remember mind-numbing details or make them stare at confusing
292     configuration screens! Life would be grand eh? Introducing the Dynamic
293     Host Configuration Protocol (DHCP) and why you should care.
294     </p>
295    
296 vapier 1.2 <p>
297     DHCP is exactly what its name implies. It's a protocol that allows you
298     to dynamically configure other hosts automatically. You run a DHCP
299     server on the router (dhcpd), give it all the information about your
300     network (valid IPs, DNS servers, gateways, etc...), and then when the
301     other hosts start up, they run a DHCP client to automatically configure
302 vapier 1.6 themselves. No fuss, no muss! For more information about DHCP, you can
303 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
304     </p>
305    
306 vapier 1.1 <pre caption="Setting up dhcpd">
307     # <i>emerge dhcp</i>
308     # <i>nano /etc/dhcp/dhcpd.conf</i>
309     <comment>Here is a sample configuration file:
310     authoritative;
311 vapier 1.19 ddns-update-style ad-hoc;
312 vapier 1.1 subnet 192.168.0.0 netmask 255.255.255.0 {
313     range 192.168.0.100 192.168.0.250;
314     default-lease-time 259200;
315     max-lease-time 518400;
316     option subnet-mask 255.255.255.0;
317     option broadcast-address 192.168.0.255;
318     option routers 192.168.0.1;
319     option domain-name-servers 192.168.0.1;
320     }
321     </comment>
322     # <i>nano /etc/conf.d/dhcp</i>
323     <comment>Set IFACE="eth0"</comment>
324     # <i>rc-update add dhcp default</i>
325     # <i>/etc/init.d/dhcp start</i>
326     </pre>
327    
328     <p>
329     Now your little router is a bona-fide DHCP server! Plugin those
330     computers and watch them work! With Windows systems you should go into
331     the TCP/IP Properties and select the 'Obtain an IP address
332     automatically' and 'Obtain DNS server address automatically' options.
333     Sometimes the changes aren't instantaneous, so you may have to run a
334     command prompt and run <c>ipconfig /release</c> and <c>ipconfig
335     /renew</c>. But enough about Windows, let's get back to our favorite
336     penguin.
337     </p>
338     </body>
339     </section>
340    
341     <section>
342     <title>DNS Server</title>
343     <body>
344 vapier 1.2 <p>
345     When people want to visit a place on the internet, they remember names,
346     not a string of useless numbers. After all, what's easier to remember,
347     ebay.com or 66.135.192.87? This is where the DNS steps in. DNS servers
348     run all over the internet, and whenever someone wants to visit 'ebay.com',
349     these servers turn 'ebay.com' (what we understand) into '66.135.192.87'
350 vapier 1.6 (what our computers understand). For more information about DNS, you can
351 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
352     </p>
353 vapier 1.1
354     <p>
355     You may have noticed in the previous section that we told the DHCP
356     clients we have a DNS server at 192.168.0.1. You may also remember that
357     192.168.0.1 is our little router that we're making. I don't remember
358     setting up a DNS server ... so let's do so now!
359     </p>
360    
361     <pre caption="Setting up dnsmasq">
362     # <i>emerge dnsmasq</i>
363     # <i>nano /etc/conf.d/dnsmasq</i>
364 vapier 1.18 <comment>Add "-i eth0" to DNSMASQ_OPTS</comment>
365 vapier 1.11 # <i>rc-update add dnsmasq default</i>
366 vapier 1.1 # <i>/etc/init.d/dnsmasq start</i>
367     </pre>
368    
369     <p>
370     Well that was quick, but what did we do? The great thing is, we didn't
371     have to do very much! You're welcome to choose other DNS servers if
372     you're more comfortable with them, but the reason dnsmasq is great is
373 vapier 1.4 because it was designed to do exactly what we want and nothing more.
374     It's a little DNS caching/forwarding server for local networks. We're
375     not looking to provide DNS for our own domain here, just offer simple DNS
376 vapier 1.1 services to everyone else on our LAN.
377     </p>
378    
379     </body>
380     </section>
381    
382     <section>
383 vapier 1.4 <title>NAT (a.k.a. IP-masquerading)</title>
384 vapier 1.1 <body>
385    
386     <p>
387     At this point, people on your network can talk to each other and they
388     can look up hostnames via DNS, but they still can't actually connect to
389     the internet. While you may think that's great (more bandwidth for
390     you!), I bet they're not too happy just yet.
391     </p>
392    
393 vapier 1.2 <p>
394     This is where NAT steps in. NAT is a way of connecting multiple computers
395     in a private LAN to the internet when you only have a smaller number of
396     IP addresses availabe to you. Typically you were given 1 IP by your ISP,
397     but you want to let your whole house connect to the internet. NAT is the
398 vapier 1.6 magic that makes this possible. For more information about NAT, you can
399 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
400     </p>
401    
402     <note>
403     Before we get started, make sure you have iptables on your system. Although
404     it is automatically installed on most systems, you may not have it. If you
405     don't, just run <c>emerge iptables</c>.
406     </note>
407    
408 vapier 1.1 <pre caption="Setting up iptables">
409     <comment>First we flush our current rules</comment>
410     # <i>iptables -F</i>
411     # <i>iptables -t nat -F</i>
412    
413     <comment>Then we lock our services so they only work from the LAN</comment>
414     # <i>iptables -I INPUT 1 -i eth0 -j ACCEPT</i>
415     # <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
416     # <i>iptables -A INPUT -p UDP --dport bootps -i ! eth0 -j REJECT</i>
417 vapier 1.12 # <i>iptables -A INPUT -p UDP --dport domain -i ! eth0 -j REJECT</i>
418 vapier 1.1
419     <comment>Drop TCP / UDP packets to privileged ports</comment>
420     # <i>iptables -A INPUT -p TCP -i ! eth0 -d 0/0 --dport 0:1023 -j DROP</i>
421     # <i>iptables -A INPUT -p UDP -i ! eth0 -d 0/0 --dport 0:1023 -j DROP</i>
422    
423     <comment>Finally we add the rules for NAT</comment>
424 vapier 1.7 # <i>iptables -I FORWARD -i eth0 -d 192.168.0.0/255.255.0.0 -j DROP</i>
425     # <i>iptables -A FORWARD -i eth0 -s 192.168.0.0/255.255.0.0 -j ACCEPT</i>
426     # <i>iptables -A FORWARD -i eth1 -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
427 vapier 1.1 # <i>iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE</i>
428     <comment>Tell the kernel that ip forwarding is OK</comment>
429     # <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i>
430     # <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
431    
432     <comment>This is so when we boot we don't have to run the rules by hand</comment>
433     # <i>/etc/init.d/iptables save</i>
434     # <i>rc-update add iptables default</i>
435 vapier 1.14 # <i>nano /etc/sysctl.conf</i>
436     <comment>Add/Uncomment the following lines:
437     net.ipv4.ip_forward = 1
438     net.ipv4.conf.default.rp_filter = 1</comment>
439 vapier 1.1 </pre>
440    
441     <p>
442     Once you've typed out all of that, the rest of your network should now
443     be able to use the internet as if they were directly connected
444 vapier 1.3 themselves.
445 vapier 1.1 </p>
446    
447 vapier 1.3 </body>
448     </section>
449     </chapter>
450    
451     <chapter>
452     <title>Fun Things (for a rainy day)</title>
453    
454     <section>
455     <title>Intro</title>
456     <body>
457 vapier 1.1 <p>
458 vapier 1.3 Believe it or not, you're done :). From here on out, I'll cover a bunch
459     of common topics that may interest you. Everything in this chapter is
460     completely optional.
461 vapier 1.1 </p>
462 vapier 1.3 </body>
463     </section>
464 vapier 1.1
465 vapier 1.3 <section>
466     <title>Port Forwarding</title>
467     <body>
468     <p>
469     Sometimes you would like to be able to host services on a computer behind
470     the router, or just to make your life easier when connecting remotely.
471     Perhaps you want to run a FTP, HTTP, SSH, or VNC server on one or more
472     machines behind your router and be able to connect to them all. The only
473     caveat is that you can only have one service/machine combo per port.
474     For example, there is no practical way to setup three FTP servers behind
475     your router and then try to connect to them all through port 21; only one
476     can be on port 21 while the others would have to be on say port 123 and
477     port 567.
478     </p>
479    
480     <p>
481     All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING
482     [-p protocol] --dport [external port on router] -i eth1 -j DNAT --to [ip/port
483     to forward to]</c>. iptables does not accept hostnames when port forwarding.
484     If you are forwarding an external port to the same port on the internal machine,
485     you can omit the destination port. See the iptables(8) page for more information.
486     </p>
487    
488     <pre>
489     <comment>Forward port 2 to ssh on an internal host</comment>
490     # <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i eth1 -j DNAT --to 192.168.0.2:22</i>
491    
492     <comment>FTP forwarding to an internal host</comment>
493     # <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i eth1 -j DNAT --to 192.168.0.56</i>
494    
495     <comment>HTTP forwarding to an internal host</comment>
496     # <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i eth1 -j DNAT --to 192.168.0.56</i>
497    
498     <comment>VNC forwarding for internal hosts</comment>
499     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i eth1 -j DNAT --to 192.168.0.2</i>
500     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i eth1 -j DNAT --to 192.168.0.3:5900</i>
501     <comment>If you want to VNC in to 192.168.0.3, then just add ':1' to the router's hostname</comment>
502    
503     <comment>Bittorrent forwarding</comment>
504     # <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i eth1 -j DNAT --to 192.168.0.2</i>
505 vapier 1.15
506     <comment>Game Cube Warp Pipe support</comment>
507     # <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i eth1 -j DNAT --to 192.168.0.56</i>
508    
509     <comment>Playstation2 Online support</comment>
510     # <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i eth1 -j DNAT --to 192.168.0.11</i>
511     # <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i eth1 -j DNAT --to 192.168.0.11</i>
512 vapier 1.3 </pre>
513    
514     <note>
515     If you have other common / cool examples, please <uri link="mailto:vapier@gentoo.org">e-mail me</uri>.
516     </note>
517     </body>
518     </section>
519    
520     <section>
521     <title>Identd (for IRC)</title>
522     <body>
523     <p>
524     Internet Relay Chat utilizes the ident service pretty heavily. Now that
525     the IRC clients are behind the router, we need a way to host ident for
526     both the router and the clients. One such server has been created
527     called <c>midentd</c>.
528     </p>
529    
530     <pre caption="Setting up ident">
531     # <i>emerge midentd</i>
532     # <i>rc-update add midentd default</i>
533     # <i>/etc/init.d/midentd start</i>
534     </pre>
535    
536     <p>
537     There are a few other ident servers in portage. Depending on your needs,
538     I would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
539     </p>
540     </body>
541     </section>
542    
543 vapier 1.5 <!--
544     <section>
545     <title>Traffic Shaping</title>
546     <body>
547     <p>
548     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>
549     found over at the TLDP. Feel free to refer to the original document
550     for more details.
551     </p>
552    
553     <p>
554     Here we will be setting up what some people refer to as a "Packet Shaper",
555     <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
556     or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
557     Simply put, we want to setup rules on our router that will slow down
558     certain activities (like sending large e-mails or downloading from P2P
559     networks) while keeping other activities (like browsing the web or playing
560     online video games) reasonably fast. A 30 second difference in a video
561     game is a lot worse than a 30 second difference in downloading large
562     files :).
563     </p>
564    
565     <p>
566     The first thing is to make sure your kernel has all the features added to
567     it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
568     information. Next, you will need to <c>emerge iptables iputils</c> so that
569     you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
570     commands.
571     </p>
572    
573     <p>
574     Before we jump into the commands, let's cover a little of the theory. The
575     way this whole system works is to classify common network streams and then
576     to prioritize them. You use iptables to classify network streams, iputils
577     to define the different priority levels, and the kernel to adjust speeds.
578     Just remember that although you can control outbound traffic pretty tightly
579     (from the LAN to the WAN), your ability to control inbound traffic (from
580     the WAN to the LAN) is somewhat limited. Just remember that the following
581     examples are to get your feet wet; if you want more then I'd suggest
582     reading up on the subject. In this example, we will be using the
583     <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
584     packet scheduling algorithm. Still with me? Great, let's start shaping :).
585     </p>
586    
587     <pre caption="Setup">
588     DEV=eth1 <comment>NIC connected to WAN</comment>
589     RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
590     RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
591    
592     <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
593     ip link set dev ${DEV} qlen 30
594     tc qdisc add dev ${DEV} root handle 1: htb default 45
595     tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
596     </pre>
597    
598     <p>
599     Here we initialized the system which will be used to prioritize all of
600     our network traffic. We created our queue, told it to use the HTB
601     algorithm, and set the default classification level to '45'. The
602     default is completely arbitrary, as are the levels we choose from
603     here on out. The only thing that matters is how the levels compare
604     relatively; a level '10' packet will be given preference over a
605     level '45' packet. Let's move on to declaring different levels.
606     </p>
607    
608     <pre caption="Declaring levels">
609     tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
610     tc qdisc add dev $DEV parent 1:10 handle 10: sfq
611     </pre>
612     </body>
613     </section>
614     -->
615    
616 vapier 1.3 <section>
617 vapier 1.9 <title>Time Server</title>
618     <body>
619     <p>
620     Keeping your system time correct is essential in maintaing a healthy
621     system. One of the most common ways of accomplishing this is with
622 vapier 1.16 the Network Time Protocol (NTP) and the ntp package (which provides
623 vapier 1.9 implementations for both server and client).
624     </p>
625    
626     <p>
627     Many people run ntp clients on their computers. Obviously, the more
628     clients in the world, the larger the load the ntp servers need to
629     shoulder. In environments like home networks though, we can help
630     keep the load down on public servers while still providing the proper
631     time to all our computers. As an added bonus, our private updates
632     will be a lot faster for the clients too! All we have to do is run
633     a ntp server on our router that synchronizes itself with the public
634     internet servers while providing the time to the rest of the computers
635     in the network. To get started, simply <c>emerge ntp</c> on the
636     router.
637     </p>
638    
639     <pre caption="Setting up the NTP server">
640     # <i>nano /etc/conf.d/ntp-client</i>
641     <comment>Customize if you wish but the defaults should be fine</comment>
642     # <i>rc-update add ntp-client default</i>
643    
644     # <i>nano /etc/ntp.conf</i>
645     <comment>Add the follwing lines:
646     restrict default ignore
647     restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
648     These will allow only ntp clients with an IP address in the 192.168.0.xxx range to use your ntp server</comment>
649     # <i>nano /etc/conf.d/ntpd</i>
650     <comment>Customize if you wish but the defaults should be fine</comment>
651 vapier 1.17 # <i>rc-update add ntpd default</i>
652 vapier 1.9
653     # <i>/etc/init.d/ntp-client start</i>
654     # <i>/etc/init.d/ntpd start</i>
655     </pre>
656    
657     <p>
658     Now, on your clients, have them <c>emerge ntp</c> also. However,
659     we will just run the ntp client so setup is a lot simpler.
660     </p>
661    
662     <pre caption="Setting up a NTP client">
663     # <i>nano /etc/conf.d/ntp-client</i>
664     <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
665     # <i>rc-update add ntp-client default</i>
666     # <i>/etc/init.d/ntp-client start</i>
667     </pre>
668     </body>
669     </section>
670    
671     <section>
672 vapier 1.3 <title>Mail Server</title>
673     <body>
674     <p>
675 vapier 1.4 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP)
676     server on the router. You may have your own reason for wanting to do so,
677     but I run it so that the users see mail as being sent instantly and the
678     work of retrying/routing is left up to the mail server. Some ISPs also
679     don't allow for mail relaying for accounts that aren't part of their
680     network (like Verizon). Also, you can easily throttle the delivery of
681     mail so that large attachments won't seriously lag your connection for
682     half an hour.
683     </p>
684    
685     <pre caption="Setting up SMTP">
686     # <i>emerge qmail</i>
687     <comment>make sure the output of `hostname` is correct</comment>
688     # <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
689 vapier 1.13 # <i>iptables -I INPUT -p tcp --dport smtp -i ! eth0 -j REJECT</i>
690 vapier 1.4 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
691 vapier 1.10 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
692 vapier 1.13 <!--
693 vapier 1.4 # <i>cd /etc/tcprules.d</i>
694     # <i>nano tcp.qmail-smtp</i>
695 vapier 1.13 -->
696     # <i>cd /etc</i>
697     # <i>nano tcp.smtp</i>
698 vapier 1.4 <comment>Add an entry like so to the allow section:
699     192.168.0.:allow,RELAYCLIENT=""</comment>
700 vapier 1.13 <!--
701 vapier 1.4 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
702 vapier 1.13 -->
703     # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
704 vapier 1.4 # <i>rc-update add svscan default</i>
705     # <i>/etc/init.d/svscan start</i>
706     </pre>
707    
708     <p>
709     I'm a huge fan of qmail, but you're free to use a different mta :).
710     When you setup e-mail on the hosts in your network, tell them that
711     their SMTP server is 192.168.0.1 and everything should be peachy.
712     You might want to visit the <uri link="http://qmail.org/">qmail
713     homepage</uri> for more documentation.
714 vapier 1.3 </p>
715     </body>
716     </section>
717    
718 vapier 1.4 <!--
719 vapier 1.3 <section>
720 vapier 1.4 <title>E-mail Virus Scanning</title>
721 vapier 1.3 <body>
722     <p>
723 vapier 1.4 If you'd like to provide e-mail virus scanning for your users, but
724     don't want to have to install a virus scanner on every single machine,
725     then <c>pop3vscan</c> may just be the thing for you; a transparent
726     Post Office Protocol (POP) scanner.
727 vapier 1.3 </p>
728 vapier 1.4
729     <pre caption="Setting up pop3vscan">
730     TODO
731     </pre>
732    
733 vapier 1.3 </body>
734     </section>
735 vapier 1.4 -->
736 vapier 1.3
737 vapier 1.4 </chapter>
738    
739     <chapter>
740     <title>Final Notes</title>
741 vapier 1.3 <section>
742     <body>
743     <p>
744 vapier 1.4 I have no final notes other than if you experience any troubles with the guide,
745     please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with
746     <uri link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If
747     you have some interesting bits you think would enhance this guide, by all means
748     send it my way for inclusion.
749 vapier 1.3 </p>
750 vapier 1.1 </body>
751     </section>
752     </chapter>
753     </guide>

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