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1 vapier 1.1 <?xml version='1.0' encoding='UTF-8'?>
2 vapier 1.14 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.13 2004/08/09 03:46:29 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     <comment>Add "-i eth1" 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     </pre>
503    
504     <note>
505     If you have other common / cool examples, please <uri link="mailto:vapier@gentoo.org">e-mail me</uri>.
506     </note>
507     </body>
508     </section>
509    
510     <section>
511     <title>Identd (for IRC)</title>
512     <body>
513     <p>
514     Internet Relay Chat utilizes the ident service pretty heavily. Now that
515     the IRC clients are behind the router, we need a way to host ident for
516     both the router and the clients. One such server has been created
517     called <c>midentd</c>.
518     </p>
519    
520     <pre caption="Setting up ident">
521     # <i>emerge midentd</i>
522     # <i>rc-update add midentd default</i>
523     # <i>/etc/init.d/midentd start</i>
524     </pre>
525    
526     <p>
527     There are a few other ident servers in portage. Depending on your needs,
528     I would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
529     </p>
530     </body>
531     </section>
532    
533 vapier 1.5 <!--
534     <section>
535     <title>Traffic Shaping</title>
536     <body>
537     <p>
538     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>
539     found over at the TLDP. Feel free to refer to the original document
540     for more details.
541     </p>
542    
543     <p>
544     Here we will be setting up what some people refer to as a "Packet Shaper",
545     <uri link="http://en.wikipedia.org/wiki/Traffic_shaping">"Traffic Shaping"</uri>,
546     or <uri link="http://en.wikipedia.org/wiki/QoS">"Quality of Service"</uri>.
547     Simply put, we want to setup rules on our router that will slow down
548     certain activities (like sending large e-mails or downloading from P2P
549     networks) while keeping other activities (like browsing the web or playing
550     online video games) reasonably fast. A 30 second difference in a video
551     game is a lot worse than a 30 second difference in downloading large
552     files :).
553     </p>
554    
555     <p>
556     The first thing is to make sure your kernel has all the features added to
557     it. See the chapter on <uri link="#doc_chap2">Kernel setup</uri> for more
558     information. Next, you will need to <c>emerge iptables iputils</c> so that
559     you will have access to the <c>iptables</c>, <c>ip</c>, and <c>tc</c>
560     commands.
561     </p>
562    
563     <p>
564     Before we jump into the commands, let's cover a little of the theory. The
565     way this whole system works is to classify common network streams and then
566     to prioritize them. You use iptables to classify network streams, iputils
567     to define the different priority levels, and the kernel to adjust speeds.
568     Just remember that although you can control outbound traffic pretty tightly
569     (from the LAN to the WAN), your ability to control inbound traffic (from
570     the WAN to the LAN) is somewhat limited. Just remember that the following
571     examples are to get your feet wet; if you want more then I'd suggest
572     reading up on the subject. In this example, we will be using the
573     <uri link="http://luxik.cdi.cz/~devik/qos/htb/">Hierarchical Token Buckets (HTB)</uri>
574     packet scheduling algorithm. Still with me? Great, let's start shaping :).
575     </p>
576    
577     <pre caption="Setup">
578     DEV=eth1 <comment>NIC connected to WAN</comment>
579     RATE_OUT=100 <comment>Available outbound bandwidth (in kilobits [kb])</comment>
580     RATE_IN=1400 <comment>Available inbound bandwidth (in kb)</comment>
581    
582     <comment>Here we initialize the priority system. The 45 is used to set the default classification level.</comment>
583     ip link set dev ${DEV} qlen 30
584     tc qdisc add dev ${DEV} root handle 1: htb default 45
585     tc class add dev ${DEV} parent 1: classid 1:1 htb rate ${RATE_OUT}kbit
586     </pre>
587    
588     <p>
589     Here we initialized the system which will be used to prioritize all of
590     our network traffic. We created our queue, told it to use the HTB
591     algorithm, and set the default classification level to '45'. The
592     default is completely arbitrary, as are the levels we choose from
593     here on out. The only thing that matters is how the levels compare
594     relatively; a level '10' packet will be given preference over a
595     level '45' packet. Let's move on to declaring different levels.
596     </p>
597    
598     <pre caption="Declaring levels">
599     tc class add dev $DEV parent 1:1 classid 1:10 htb rate $rkbit ceil $tkbit prio $p
600     tc qdisc add dev $DEV parent 1:10 handle 10: sfq
601     </pre>
602     </body>
603     </section>
604     -->
605    
606 vapier 1.3 <section>
607 vapier 1.9 <title>Time Server</title>
608     <body>
609     <p>
610     Keeping your system time correct is essential in maintaing a healthy
611     system. One of the most common ways of accomplishing this is with
612     the Network Time Protocol [NTP] and the ntp package (which provides
613     implementations for both server and client).
614     </p>
615    
616     <p>
617     Many people run ntp clients on their computers. Obviously, the more
618     clients in the world, the larger the load the ntp servers need to
619     shoulder. In environments like home networks though, we can help
620     keep the load down on public servers while still providing the proper
621     time to all our computers. As an added bonus, our private updates
622     will be a lot faster for the clients too! All we have to do is run
623     a ntp server on our router that synchronizes itself with the public
624     internet servers while providing the time to the rest of the computers
625     in the network. To get started, simply <c>emerge ntp</c> on the
626     router.
627     </p>
628    
629     <pre caption="Setting up the NTP server">
630     # <i>nano /etc/conf.d/ntp-client</i>
631     <comment>Customize if you wish but the defaults should be fine</comment>
632     # <i>rc-update add ntp-client default</i>
633    
634     # <i>nano /etc/ntp.conf</i>
635     <comment>Add the follwing lines:
636     restrict default ignore
637     restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
638     These will allow only ntp clients with an IP address in the 192.168.0.xxx range to use your ntp server</comment>
639     # <i>nano /etc/conf.d/ntpd</i>
640     <comment>Customize if you wish but the defaults should be fine</comment>
641    
642     # <i>/etc/init.d/ntp-client start</i>
643     # <i>/etc/init.d/ntpd start</i>
644     </pre>
645    
646     <p>
647     Now, on your clients, have them <c>emerge ntp</c> also. However,
648     we will just run the ntp client so setup is a lot simpler.
649     </p>
650    
651     <pre caption="Setting up a NTP client">
652     # <i>nano /etc/conf.d/ntp-client</i>
653     <comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
654     # <i>rc-update add ntp-client default</i>
655     # <i>/etc/init.d/ntp-client start</i>
656     </pre>
657     </body>
658     </section>
659    
660     <section>
661 vapier 1.3 <title>Mail Server</title>
662     <body>
663     <p>
664 vapier 1.4 Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP)
665     server on the router. You may have your own reason for wanting to do so,
666     but I run it so that the users see mail as being sent instantly and the
667     work of retrying/routing is left up to the mail server. Some ISPs also
668     don't allow for mail relaying for accounts that aren't part of their
669     network (like Verizon). Also, you can easily throttle the delivery of
670     mail so that large attachments won't seriously lag your connection for
671     half an hour.
672     </p>
673    
674     <pre caption="Setting up SMTP">
675     # <i>emerge qmail</i>
676     <comment>make sure the output of `hostname` is correct</comment>
677     # <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
678 vapier 1.13 # <i>iptables -I INPUT -p tcp --dport smtp -i ! eth0 -j REJECT</i>
679 vapier 1.4 # <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
680 vapier 1.10 # <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
681 vapier 1.13 <!--
682 vapier 1.4 # <i>cd /etc/tcprules.d</i>
683     # <i>nano tcp.qmail-smtp</i>
684 vapier 1.13 -->
685     # <i>cd /etc</i>
686     # <i>nano tcp.smtp</i>
687 vapier 1.4 <comment>Add an entry like so to the allow section:
688     192.168.0.:allow,RELAYCLIENT=""</comment>
689 vapier 1.13 <!--
690 vapier 1.4 # <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
691 vapier 1.13 -->
692     # <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
693 vapier 1.4 # <i>rc-update add svscan default</i>
694     # <i>/etc/init.d/svscan start</i>
695     </pre>
696    
697     <p>
698     I'm a huge fan of qmail, but you're free to use a different mta :).
699     When you setup e-mail on the hosts in your network, tell them that
700     their SMTP server is 192.168.0.1 and everything should be peachy.
701     You might want to visit the <uri link="http://qmail.org/">qmail
702     homepage</uri> for more documentation.
703 vapier 1.3 </p>
704     </body>
705     </section>
706    
707 vapier 1.4 <!--
708 vapier 1.3 <section>
709 vapier 1.4 <title>E-mail Virus Scanning</title>
710 vapier 1.3 <body>
711     <p>
712 vapier 1.4 If you'd like to provide e-mail virus scanning for your users, but
713     don't want to have to install a virus scanner on every single machine,
714     then <c>pop3vscan</c> may just be the thing for you; a transparent
715     Post Office Protocol (POP) scanner.
716 vapier 1.3 </p>
717 vapier 1.4
718     <pre caption="Setting up pop3vscan">
719     TODO
720     </pre>
721    
722 vapier 1.3 </body>
723     </section>
724 vapier 1.4 -->
725 vapier 1.3
726 vapier 1.4 </chapter>
727    
728     <chapter>
729     <title>Final Notes</title>
730 vapier 1.3 <section>
731     <body>
732     <p>
733 vapier 1.4 I have no final notes other than if you experience any troubles with the guide,
734     please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with
735     <uri link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If
736     you have some interesting bits you think would enhance this guide, by all means
737     send it my way for inclusion.
738 vapier 1.3 </p>
739 vapier 1.1 </body>
740     </section>
741     </chapter>
742     </guide>

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