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LAN interface is eth0, not eth1 ... thanks to Ville Heikkilä

1 vapier 1.1 <?xml version='1.0' encoding='UTF-8'?>
2 vapier 1.18 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.17 2004/08/12 04:52:20 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    
124     <i> IP: Netfilter Configuration ---&gt;</i>
125     <i> [*] Connection tracking (required for masq/NAT)</i>
126     <i> [x] FTP protocol support</i>
127     <i> [x] IRC protocol support</i>
128     <i> [*] IP tables support (required for filtering/masq/NAT)</i>
129     <i> [*] IP range match support</i>
130     <i> [x] MAC address match support</i>
131     <i> [*] Multiple port match support</i>
132     <i> [*] Packet filtering</i>
133     <i> [*] REJECT target support</i>
134     <i> [x] REDIRECT target support</i>
135     <i> [*] Full NAT</i>
136     <i> [*] MASQUERADE target support</i>
137     <i> [s] Packet mangling</i>
138     <i> [s] MARK target support</i>
139     <i> [x] LOG target support</i>
140    
141     <i> QoS and/or fair queueing ---&gt;</i>
142     <i> [s] QoS and/or fair queueing</i>
143     <i> [s] HTB packet scheduler</i>
144     <i> [s] Ingress Qdisc</i>
145     </pre>
146     <note>
147     Somethings may be slightly different in a 2.4 vs 2.6 kernel, but you
148 vapier 1.3 should be able to figure it out :).
149 vapier 1.1 </note>
150    
151     </body>
152     </section>
153     </chapter>
154    
155     <chapter>
156     <title>Hug the WAN (a.k.a. The Internet)</title>
157    
158     <section>
159     <title>Intro</title>
160     <body>
161     <p>
162     There are many ways to connect to the internet so I'll just cover the
163     ones I'm familiar with. That leaves us with ADSL (PPPoE) and cable
164     modems (static/dynamic). If there are other methods out there, feel
165     free to write up a little blurb and e-mail me. Feel free to skip any of
166     the following sections in this chapter that don't apply to you. This
167     chapter is just about getting the router connected to the internet via
168     eth1.
169     </p>
170     </body>
171     </section>
172    
173     <section>
174     <title>ADSL and PPPoE</title>
175     <body>
176    
177     <p>
178     All the fancy PPPoE software has been bundled up into one little nice
179     package nowadays called <uri link="http://www.roaringpenguin.com/">Roaring Penguin</uri>.
180     Simply <c>emerge rp-pppoe</c> and you'll be on your way. Remember how
181     I said you'll need username/password information? Well I wasn't lying
182     so I hope you have it now! Load up <path>/etc/ppp/pppoe.conf</path> in
183     your favorite editor and set it up.
184     </p>
185    
186 vapier 1.8 <note>
187     In order for the following net.eth1 settings to work, you must have
188     baselayout-1.10.1 or later installed on your system.
189     </note>
190    
191 vapier 1.1 <pre caption="Setting up eth1">
192     <comment>(Replace 'vla9h924' with your username and 'password' with your password)</comment>
193    
194     # <i>nano /etc/ppp/pppoe.conf</i>
195     <comment># Ethernet card connected to ADSL modem
196     ETH=eth1
197     # ADSL user name.
198     USER=vla9h924</comment>
199     # <i>nano /etc/ppp/pap-secrets</i>
200     <comment># client server secret
201     "vla9h924" * "password"</comment>
202     # <i>nano /etc/conf.d/net</i>
203     <comment>Add an entry for ifconfig_eth1 and set it to adsl:
204     ifconfig_eth1=( "adsl" )</comment>
205     # <i>ln -s net.eth0 /etc/init.d/net.eth1</i>
206     # <i>rc-update add net.eth1 default</i>
207     # <i>/etc/init.d/net.eth1 start</i>
208     </pre>
209    
210 vapier 1.3 <warn>
211     When the DSL interface comes up, it will create ppp0. Although your NIC
212     is called eth1, the IP is actually bound to ppp0. From now on, when you
213     see examples that utilize 'eth1', substitute with 'ppp0'.
214     </warn>
215 vapier 1.1
216     </body>
217     </section>
218    
219     <section>
220     <title>Cable and/or dynamic/static IP</title>
221     <body>
222    
223     <p>
224 vapier 1.4 If you have a static IP then you will need a few more details than if
225 vapier 1.1 you have a dynamic IP. For static users, you will need your IP,
226     gateway, and DNS servers.
227     </p>
228    
229     <pre caption="Setting up eth1">
230     <comment>Dynamic IP Users:</comment>
231     # <i>emerge dhcpcd</i>
232     # <i>nano /etc/conf.d/net</i>
233     <comment>You'll need an entry like so:
234     ifconfig_eth1=( "dhcp" )</comment>
235    
236     <comment>Static IP Users:</comment>
237     # <i>nano /etc/conf.d/net</i>
238     <comment>You'll need entries like so:
239     ifconfig_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" )
240     routes_eth1=( "default gw 66.92.78.1" )</comment>
241     # <i>nano /etc/resolv.conf</i>
242     <comment>Add one line per DNS server:
243     nameserver 123.123.123.123</comment>
244    
245     <comment>Dynamic and Static Setup:</comment>
246     # <i>ln -s net.eth0 /etc/init.d/net.eth1</i>
247     # <i>rc-update add net.eth1 default</i>
248     # <i>/etc/init.d/net.eth1 start</i>
249     </pre>
250    
251     <p>
252     You should be all set to go now.
253     </p>
254    
255     </body>
256     </section>
257     </chapter>
258    
259     <chapter>
260     <title>Hug the LAN (bring along some friends)</title>
261     <section>
262     <body>
263    
264     <p>
265     This step is a breeze compared to the previous one.
266     </p>
267    
268     <pre caption="Setting up eth0">
269     # <i>nano /etc/conf.d/net</i>
270     <comment>Add a line like the following:
271     ifconfig_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )</comment>
272     # <i>rc-update add net.eth0 default</i>
273     # <i>/etc/init.d/net.eth0 start</i>
274     </pre>
275    
276     </body>
277     </section>
278     </chapter>
279    
280     <chapter>
281     <title>LAN Services (because we're nice people)</title>
282    
283     <section>
284     <title>DHCP Server</title>
285     <body>
286     <p>
287     I bet it'd be nice if everyone else in your house could just plug
288     their computers into the network and things would just work. No need to
289     remember mind-numbing details or make them stare at confusing
290     configuration screens! Life would be grand eh? Introducing the Dynamic
291     Host Configuration Protocol (DHCP) and why you should care.
292     </p>
293    
294 vapier 1.2 <p>
295     DHCP is exactly what its name implies. It's a protocol that allows you
296     to dynamically configure other hosts automatically. You run a DHCP
297     server on the router (dhcpd), give it all the information about your
298     network (valid IPs, DNS servers, gateways, etc...), and then when the
299     other hosts start up, they run a DHCP client to automatically configure
300 vapier 1.6 themselves. No fuss, no muss! For more information about DHCP, you can
301 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
302     </p>
303    
304 vapier 1.1 <pre caption="Setting up dhcpd">
305     # <i>emerge dhcp</i>
306     # <i>nano /etc/dhcp/dhcpd.conf</i>
307     <comment>Here is a sample configuration file:
308     authoritative;
309     subnet 192.168.0.0 netmask 255.255.255.0 {
310     range 192.168.0.100 192.168.0.250;
311     default-lease-time 259200;
312     max-lease-time 518400;
313     option subnet-mask 255.255.255.0;
314     option broadcast-address 192.168.0.255;
315     option routers 192.168.0.1;
316     option domain-name-servers 192.168.0.1;
317     }
318     </comment>
319     # <i>nano /etc/conf.d/dhcp</i>
320     <comment>Set IFACE="eth0"</comment>
321     # <i>rc-update add dhcp default</i>
322     # <i>/etc/init.d/dhcp start</i>
323     </pre>
324    
325     <p>
326     Now your little router is a bona-fide DHCP server! Plugin those
327     computers and watch them work! With Windows systems you should go into
328     the TCP/IP Properties and select the 'Obtain an IP address
329     automatically' and 'Obtain DNS server address automatically' options.
330     Sometimes the changes aren't instantaneous, so you may have to run a
331     command prompt and run <c>ipconfig /release</c> and <c>ipconfig
332     /renew</c>. But enough about Windows, let's get back to our favorite
333     penguin.
334     </p>
335     </body>
336     </section>
337    
338     <section>
339     <title>DNS Server</title>
340     <body>
341 vapier 1.2 <p>
342     When people want to visit a place on the internet, they remember names,
343     not a string of useless numbers. After all, what's easier to remember,
344     ebay.com or 66.135.192.87? This is where the DNS steps in. DNS servers
345     run all over the internet, and whenever someone wants to visit 'ebay.com',
346     these servers turn 'ebay.com' (what we understand) into '66.135.192.87'
347 vapier 1.6 (what our computers understand). For more information about DNS, you can
348 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
349     </p>
350 vapier 1.1
351     <p>
352     You may have noticed in the previous section that we told the DHCP
353     clients we have a DNS server at 192.168.0.1. You may also remember that
354     192.168.0.1 is our little router that we're making. I don't remember
355     setting up a DNS server ... so let's do so now!
356     </p>
357    
358     <pre caption="Setting up dnsmasq">
359     # <i>emerge dnsmasq</i>
360     # <i>nano /etc/conf.d/dnsmasq</i>
361 vapier 1.18 <comment>Add "-i eth0" to DNSMASQ_OPTS</comment>
362 vapier 1.11 # <i>rc-update add dnsmasq default</i>
363 vapier 1.1 # <i>/etc/init.d/dnsmasq start</i>
364     </pre>
365    
366     <p>
367     Well that was quick, but what did we do? The great thing is, we didn't
368     have to do very much! You're welcome to choose other DNS servers if
369     you're more comfortable with them, but the reason dnsmasq is great is
370 vapier 1.4 because it was designed to do exactly what we want and nothing more.
371     It's a little DNS caching/forwarding server for local networks. We're
372     not looking to provide DNS for our own domain here, just offer simple DNS
373 vapier 1.1 services to everyone else on our LAN.
374     </p>
375    
376     </body>
377     </section>
378    
379     <section>
380 vapier 1.4 <title>NAT (a.k.a. IP-masquerading)</title>
381 vapier 1.1 <body>
382    
383     <p>
384     At this point, people on your network can talk to each other and they
385     can look up hostnames via DNS, but they still can't actually connect to
386     the internet. While you may think that's great (more bandwidth for
387     you!), I bet they're not too happy just yet.
388     </p>
389    
390 vapier 1.2 <p>
391     This is where NAT steps in. NAT is a way of connecting multiple computers
392     in a private LAN to the internet when you only have a smaller number of
393     IP addresses availabe to you. Typically you were given 1 IP by your ISP,
394     but you want to let your whole house connect to the internet. NAT is the
395 vapier 1.6 magic that makes this possible. For more information about NAT, you can
396 vapier 1.2 always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
397     </p>
398    
399     <note>
400     Before we get started, make sure you have iptables on your system. Although
401     it is automatically installed on most systems, you may not have it. If you
402     don't, just run <c>emerge iptables</c>.
403     </note>
404    
405 vapier 1.1 <pre caption="Setting up iptables">
406     <comment>First we flush our current rules</comment>
407     # <i>iptables -F</i>
408     # <i>iptables -t nat -F</i>
409    
410     <comment>Then we lock our services so they only work from the LAN</comment>
411     # <i>iptables -I INPUT 1 -i eth0 -j ACCEPT</i>
412     # <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
413     # <i>iptables -A INPUT -p UDP --dport bootps -i ! eth0 -j REJECT</i>
414 vapier 1.12 # <i>iptables -A INPUT -p UDP --dport domain -i ! eth0 -j REJECT</i>
415 vapier 1.1
416     <comment>Drop TCP / UDP packets to privileged ports</comment>
417     # <i>iptables -A INPUT -p TCP -i ! eth0 -d 0/0 --dport 0:1023 -j DROP</i>
418     # <i>iptables -A INPUT -p UDP -i ! eth0 -d 0/0 --dport 0:1023 -j DROP</i>
419    
420     <comment>Finally we add the rules for NAT</comment>
421 vapier 1.7 # <i>iptables -I FORWARD -i eth0 -d 192.168.0.0/255.255.0.0 -j DROP</i>
422     # <i>iptables -A FORWARD -i eth0 -s 192.168.0.0/255.255.0.0 -j ACCEPT</i>
423     # <i>iptables -A FORWARD -i eth1 -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
424 vapier 1.1 # <i>iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE</i>
425     <comment>Tell the kernel that ip forwarding is OK</comment>
426     # <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i>
427     # <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
428    
429     <comment>This is so when we boot we don't have to run the rules by hand</comment>
430     # <i>/etc/init.d/iptables save</i>
431     # <i>rc-update add iptables default</i>
432 vapier 1.14 # <i>nano /etc/sysctl.conf</i>
433     <comment>Add/Uncomment the following lines:
434     net.ipv4.ip_forward = 1
435     net.ipv4.conf.default.rp_filter = 1</comment>
436 vapier 1.1 </pre>
437    
438     <p>
439     Once you've typed out all of that, the rest of your network should now
440     be able to use the internet as if they were directly connected
441 vapier 1.3 themselves.
442 vapier 1.1 </p>
443    
444 vapier 1.3 </body>
445     </section>
446     </chapter>
447    
448     <chapter>
449     <title>Fun Things (for a rainy day)</title>
450    
451     <section>
452     <title>Intro</title>
453     <body>
454 vapier 1.1 <p>
455 vapier 1.3 Believe it or not, you're done :). From here on out, I'll cover a bunch
456     of common topics that may interest you. Everything in this chapter is
457     completely optional.
458 vapier 1.1 </p>
459 vapier 1.3 </body>
460     </section>
461 vapier 1.1
462 vapier 1.3 <section>
463     <title>Port Forwarding</title>
464     <body>
465     <p>
466     Sometimes you would like to be able to host services on a computer behind
467     the router, or just to make your life easier when connecting remotely.
468     Perhaps you want to run a FTP, HTTP, SSH, or VNC server on one or more
469     machines behind your router and be able to connect to them all. The only
470     caveat is that you can only have one service/machine combo per port.
471     For example, there is no practical way to setup three FTP servers behind
472     your router and then try to connect to them all through port 21; only one
473     can be on port 21 while the others would have to be on say port 123 and
474     port 567.
475     </p>
476    
477     <p>
478     All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING
479     [-p protocol] --dport [external port on router] -i eth1 -j DNAT --to [ip/port
480     to forward to]</c>. iptables does not accept hostnames when port forwarding.
481     If you are forwarding an external port to the same port on the internal machine,
482     you can omit the destination port. See the iptables(8) page for more information.
483     </p>
484    
485     <pre>
486     <comment>Forward port 2 to ssh on an internal host</comment>
487     # <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i eth1 -j DNAT --to 192.168.0.2:22</i>
488    
489     <comment>FTP forwarding to an internal host</comment>
490     # <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i eth1 -j DNAT --to 192.168.0.56</i>
491    
492     <comment>HTTP forwarding to an internal host</comment>
493     # <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i eth1 -j DNAT --to 192.168.0.56</i>
494    
495     <comment>VNC forwarding for internal hosts</comment>
496     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i eth1 -j DNAT --to 192.168.0.2</i>
497     # <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i eth1 -j DNAT --to 192.168.0.3:5900</i>
498     <comment>If you want to VNC in to 192.168.0.3, then just add ':1' to the router's hostname</comment>
499    
500     <comment>Bittorrent forwarding</comment>
501     # <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i eth1 -j DNAT --to 192.168.0.2</i>
502 vapier 1.15
503     <comment>Game Cube Warp Pipe support</comment>
504     # <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i eth1 -j DNAT --to 192.168.0.56</i>
505    
506     <comment>Playstation2 Online support</comment>
507     # <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i eth1 -j DNAT --to 192.168.0.11</i>
508     # <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i eth1 -j DNAT --to 192.168.0.11</i>
509 vapier 1.3 </pre>
510    
511     <note>
512     If you have other common / cool examples, please <uri link="mailto:vapier@gentoo.org">e-mail me</uri>.
513     </note>
514     </body>
515     </section>
516    
517     <section>
518     <title>Identd (for IRC)</title>
519     <body>
520     <p>
521     Internet Relay Chat utilizes the ident service pretty heavily. Now that
522     the IRC clients are behind the router, we need a way to host ident for
523     both the router and the clients. One such server has been created
524     called <c>midentd</c>.
525     </p>
526    
527     <pre caption="Setting up ident">
528     # <i>emerge midentd</i>
529     # <i>rc-update add midentd default</i>
530     # <i>/etc/init.d/midentd start</i>
531     </pre>
532    
533     <p>
534     There are a few other ident servers in portage. Depending on your needs,
535     I would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
536     </p>
537     </body>
538     </section>
539    
540 vapier 1.5 <!--
541     <section>
542     <title>Traffic Shaping</title>
543     <body>
544     <p>
545     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>
546     found over at the TLDP. Feel free to refer to the original document
547     for more details.
548     </p>
549    
550     <p>
551     Here we will be setting up what some people refer to as a "Packet Shaper",
552     <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
553     or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
554     Simply put, we want to setup rules on our router that will slow down
555     certain activities (like sending large e-mails or downloading from P2P
556     networks) while keeping other activities (like browsing the web or playing
557     online video games) reasonably fast. A 30 second difference in a video
558     game is a lot worse than a 30 second difference in downloading large
559     files :).
560     </p>
561    
562     <p>
563     The first thing is to make sure your kernel has all the features added to
564     it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
565     information. Next, you will need to <c>emerge iptables iputils</c> so that
566     you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
567     commands.
568     </p>
569    
570     <p>
571     Before we jump into the commands, let's cover a little of the theory. The
572     way this whole system works is to classify common network streams and then
573     to prioritize them. You use iptables to classify network streams, iputils
574     to define the different priority levels, and the kernel to adjust speeds.
575     Just remember that although you can control outbound traffic pretty tightly
576     (from the LAN to the WAN), your ability to control inbound traffic (from
577     the WAN to the LAN) is somewhat limited. Just remember that the following
578     examples are to get your feet wet; if you want more then I'd suggest
579     reading up on the subject. In this example, we will be using the
580     <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
581     packet scheduling algorithm. Still with me? Great, let's start shaping :).
582     </p>
583    
584     <pre caption="Setup">
585     DEV=eth1 <comment>NIC connected to WAN</comment>
586     RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
587     RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
588    
589     <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
590     ip link set dev ${DEV} qlen 30
591     tc qdisc add dev ${DEV} root handle 1: htb default 45
592     tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
593     </pre>
594    
595     <p>
596     Here we initialized the system which will be used to prioritize all of
597     our network traffic. We created our queue, told it to use the HTB
598     algorithm, and set the default classification level to '45'. The
599     default is completely arbitrary, as are the levels we choose from
600     here on out. The only thing that matters is how the levels compare
601     relatively; a level '10' packet will be given preference over a
602     level '45' packet. Let's move on to declaring different levels.
603     </p>
604    
605     <pre caption="Declaring levels">
606     tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
607     tc qdisc add dev $DEV parent 1:10 handle 10: sfq
608     </pre>
609     </body>
610     </section>
611     -->
612    
613 vapier 1.3 <section>
614 vapier 1.9 <title>Time Server</title>
615     <body>
616     <p>
617     Keeping your system time correct is essential in maintaing a healthy
618     system. One of the most common ways of accomplishing this is with
619 vapier 1.16 the Network Time Protocol (NTP) and the ntp package (which provides
620 vapier 1.9 implementations for both server and client).
621     </p>
622    
623     <p>
624     Many people run ntp clients on their computers. Obviously, the more
625     clients in the world, the larger the load the ntp servers need to
626     shoulder. In environments like home networks though, we can help
627     keep the load down on public servers while still providing the proper
628     time to all our computers. As an added bonus, our private updates
629     will be a lot faster for the clients too! All we have to do is run
630     a ntp server on our router that synchronizes itself with the public
631     internet servers while providing the time to the rest of the computers
632     in the network. To get started, simply <c>emerge ntp</c> on the
633     router.
634     </p>
635    
636     <pre caption="Setting up the NTP server">
637     # <i>nano /etc/conf.d/ntp-client</i>
638     <comment>Customize if you wish but the defaults should be fine</comment>
639     # <i>rc-update add ntp-client default</i>
640    
641     # <i>nano /etc/ntp.conf</i>
642     <comment>Add the follwing lines:
643     restrict default ignore
644     restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
645     These will allow only ntp clients with an IP address in the 192.168.0.xxx range to use your ntp server</comment>
646     # <i>nano /etc/conf.d/ntpd</i>
647     <comment>Customize if you wish but the defaults should be fine</comment>
648 vapier 1.17 # <i>rc-update add ntpd default</i>
649 vapier 1.9
650     # <i>/etc/init.d/ntp-client start</i>
651     # <i>/etc/init.d/ntpd start</i>
652     </pre>
653    
654     <p>
655     Now, on your clients, have them <c>emerge ntp</c> also. However,
656     we will just run the ntp client so setup is a lot simpler.
657     </p>
658    
659     <pre caption="Setting up a NTP client">
660     # <i>nano /etc/conf.d/ntp-client</i>
661     <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
662     # <i>rc-update add ntp-client default</i>
663     # <i>/etc/init.d/ntp-client start</i>
664     </pre>
665     </body>
666     </section>
667    
668     <section>
669 vapier 1.3 <title>Mail Server</title>
670     <body>
671     <p>
672 vapier 1.4 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP)
673     server on the router. You may have your own reason for wanting to do so,
674     but I run it so that the users see mail as being sent instantly and the
675     work of retrying/routing is left up to the mail server. Some ISPs also
676     don't allow for mail relaying for accounts that aren't part of their
677     network (like Verizon). Also, you can easily throttle the delivery of
678     mail so that large attachments won't seriously lag your connection for
679     half an hour.
680     </p>
681    
682     <pre caption="Setting up SMTP">
683     # <i>emerge qmail</i>
684     <comment>make sure the output of `hostname` is correct</comment>
685     # <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
686 vapier 1.13 # <i>iptables -I INPUT -p tcp --dport smtp -i ! eth0 -j REJECT</i>
687 vapier 1.4 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
688 vapier 1.10 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
689 vapier 1.13 <!--
690 vapier 1.4 # <i>cd /etc/tcprules.d</i>
691     # <i>nano tcp.qmail-smtp</i>
692 vapier 1.13 -->
693     # <i>cd /etc</i>
694     # <i>nano tcp.smtp</i>
695 vapier 1.4 <comment>Add an entry like so to the allow section:
696     192.168.0.:allow,RELAYCLIENT=""</comment>
697 vapier 1.13 <!--
698 vapier 1.4 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
699 vapier 1.13 -->
700     # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
701 vapier 1.4 # <i>rc-update add svscan default</i>
702     # <i>/etc/init.d/svscan start</i>
703     </pre>
704    
705     <p>
706     I'm a huge fan of qmail, but you're free to use a different mta :).
707     When you setup e-mail on the hosts in your network, tell them that
708     their SMTP server is 192.168.0.1 and everything should be peachy.
709     You might want to visit the <uri link="http://qmail.org/">qmail
710     homepage</uri> for more documentation.
711 vapier 1.3 </p>
712     </body>
713     </section>
714    
715 vapier 1.4 <!--
716 vapier 1.3 <section>
717 vapier 1.4 <title>E-mail Virus Scanning</title>
718 vapier 1.3 <body>
719     <p>
720 vapier 1.4 If you'd like to provide e-mail virus scanning for your users, but
721     don't want to have to install a virus scanner on every single machine,
722     then <c>pop3vscan</c> may just be the thing for you; a transparent
723     Post Office Protocol (POP) scanner.
724 vapier 1.3 </p>
725 vapier 1.4
726     <pre caption="Setting up pop3vscan">
727     TODO
728     </pre>
729    
730 vapier 1.3 </body>
731     </section>
732 vapier 1.4 -->
733 vapier 1.3
734 vapier 1.4 </chapter>
735    
736     <chapter>
737     <title>Final Notes</title>
738 vapier 1.3 <section>
739     <body>
740     <p>
741 vapier 1.4 I have no final notes other than if you experience any troubles with the guide,
742     please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with
743     <uri link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If
744     you have some interesting bits you think would enhance this guide, by all means
745     send it my way for inclusion.
746 vapier 1.3 </p>
747 vapier 1.1 </body>
748     </section>
749     </chapter>
750     </guide>

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