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1<?xml version='1.0' encoding='UTF-8'?> 1<?xml version='1.0' encoding='UTF-8'?>
2<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.15 2004/08/12 03:37:25 vapier Exp $ -->
3<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> 2<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/home-router-howto.xml,v 1.50 2006/08/21 10:47:36 vapier Exp $ -->
4 4
5<guide link="/doc/en/home-router-howto.xml"> 5<guide link="/doc/en/home-router-howto.xml" lang="en">
6
7<title>Home Router Guide</title> 6<title>Home Router Guide</title>
8 7
9<author title="Author"> 8<author title="Author">
10 <mail link="vapier@gentoo.org">Mike Frysinger</mail> 9 <mail link="vapier@gentoo.org">Mike Frysinger</mail>
11</author> 10</author>
13<abstract> 12<abstract>
14This document details how to turn an old Gentoo machine into a router 13This document details how to turn an old Gentoo machine into a router
15for connecting your home network to the internet. 14for connecting your home network to the internet.
16</abstract> 15</abstract>
17 16
17<!-- The content of this document is released into the public domain -->
18<license/>
19
18<version>1.1</version> 20<version>1.31</version>
19<date>July 21, 2004</date> 21<date>2006-08-21</date>
20 22
21<chapter> 23<chapter>
22<title>Introduction</title> 24<title>Introduction</title>
23<section> 25<section>
24<body> 26<body>
25 27
26<p> 28<p>
27Building your own router out of old spare parts has many advantages 29Building your own router out of old spare parts has many advantages over buying
28over buying a pre-made canned router by say Linksys. The biggest one by 30a pre-made canned router by say Linksys. The biggest one by far is control
29far is control over the connection. The other advantages are left up to 31over the connection. The other advantages are left up to your imagination;
30your imagination; just about anything can be done in this scenario, 32just about anything can be done in this scenario, it's just a matter of needing
31it's just a matter of needing it. 33it.
32</p>
33
34<p> 34</p>
35
36<p>
35This guide will show you how to setup Network Address Translation (NAT) 37This guide will show you how to setup Network Address Translation (NAT) on the
36on the router (kernel and iptables), add and configure common services 38router (kernel and iptables), add and configure common services (Domain Name
37(Domain Name System (DNS) via dnsmasq, dhcp via dhcpcd, ADSL via 39System (DNS) via dnsmasq, dhcp via dhcpcd, ADSL via rp-pppoe), and conclude
38rp-pppoe), and conclude with more elaborate and fun things that can be 40with more elaborate and fun things that can be done (port forwarding, traffic
39done (port forwarding, traffic shaping, proxies/caching, etc...). 41shaping, proxies/caching, etc...).
40</p>
41
42<p> 42</p>
43
44<p>
43Before getting started, there's a few basic requirements you must meet. 45Before getting started, there's a few basic requirements you must meet. First,
44First, you'll need a computer that has at least 2 Network Interface 46you'll need a computer that has at least 2 Network Interface Cards (NICs) in
45Cards (NICs) in it. Next, you'll need the configuration settings for 47it. Next, you'll need the configuration settings for your internet connection
46your internet connection (may include things like 48(may include things like IP/DNS/Gateway/username/password). Finally, you'll
47IP/DNS/Gateway/username/password). Finally, you'll need a bit of spare 49need a bit of spare time and some Gentoo loving.
48time and some Gentoo loving.
49</p> 50</p>
50 51
51<p> 52<p>
52The conventions used in this guide are: 53The conventions used in this guide are:
53</p> 54</p>
55
54<ul> 56<ul>
55 <li>eth0 - NIC connected to the Local Area Network (LAN)</li> 57 <li>eth0 - NIC connected to the Local Area Network (LAN)</li>
56 <li>eth1 - NIC connected to the Wide Area Network (WAN)</li> 58 <li>eth1 - NIC connected to the Wide Area Network (WAN)</li>
57 <li>LAN utilizes the private 192.168.0.xxx network</li> 59 <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> 60 <li>router is hardcoded to the standard 192.168.0.1 IP</li>
59 <li>router is running Linux 2.4 or 2.6; you're on your own with 2.0/2.2</li> 61 <li>router is running Linux 2.4 or 2.6; you're on your own with 2.0/2.2</li>
60</ul> 62</ul>
61 63
62<impo> 64<impo>
63Due to security precautions, I would highly suggest you shut down any 65Due to security precautions, I would highly suggest you shut down any unneeded
64unneeded services on the router until we have a chance to get the 66services on the router until we have a chance to get the firewall up and
65firewall up and rolling. To view the currently running services, just 67rolling. To view the currently running services, just run <c>rc-status</c>.
66run <c>rc-status</c>.
67</impo> 68</impo>
68 69
69</body> 70</body>
70</section> 71</section>
71</chapter> 72</chapter>
74<title>Kernel setup (know thyself first)</title> 75<title>Kernel setup (know thyself first)</title>
75<section> 76<section>
76<body> 77<body>
77 78
78<p> 79<p>
79Your kernel needs to have the drivers running for both your NICs. To 80Your kernel needs to have the drivers running for both your NICs. To see if
80see if your cards are already setup, just run <c>ifconfig</c>. Your 81your cards are already setup, just run <c>ifconfig</c>. Your output may differ
81output may differ slightly from the following, that's fine. What 82slightly from the following, that's fine. What matters is that the interface
82matters is that the interface shows up at all. 83shows up at all.
83</p> 84</p>
85
84<pre caption="Checking NICs"> 86<pre caption="Checking NICs">
85# <i>ifconfig -a</i> 87# <i>ifconfig -a</i>
86eth0 Link encap:Ethernet HWaddr 00:60:F5:07:07:B8 88eth0 Link encap:Ethernet HWaddr 00:60:F5:07:07:B8
87 BROADCAST MULTICAST MTU:1500 Metric:1 89 BROADCAST MULTICAST MTU:1500 Metric:1
88 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 90 RX packets:0 errors:0 dropped:0 overruns:0 frame:0
97 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 99 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
98 collisions:0 txqueuelen:1000 100 collisions:0 txqueuelen:1000
99 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) 101 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
100 Interrupt:10 Base address:0x9400 102 Interrupt:10 Base address:0x9400
101</pre> 103</pre>
104
102<p> 105<p>
103If you do not see your two cards showing up and you're not sure what 106If you do not see your two cards showing up and you're not sure what kind of
104kind of cards you have, try running <c>lspci</c>. You can get that from 107cards you have, try running <c>lspci | grep Ethernet</c>. You can get that
105<c>emerge pciutils</c>. Look for "Ethernet controller" in the output. 108from <c>emerge pciutils</c>. Once you have this information, go into your
106Once you have this information, go into your kernel and add support for 109kernel and add support for the correct drivers.
107the correct drivers.
108</p>
109
110<p> 110</p>
111
112<p>
111The next thing you'll need is support for iptables and NAT (and packet 113The next thing you'll need is support for iptables and NAT (and packet shaping
112shaping if you want). The following list is split up into required 114if you want). The following list is split up into always required (*),
113(*), suggested (x), and shaper (s) features. It does not matter whether 115required only for adsl via PPPoE (a), suggested for everyone (x), and only
114you build the features into the kernel or as a module so long as when 116for shaper (s) features. It does not matter whether you build the features
115the feature is needed, the correct module(s) are loaded (module loading 117into the kernel or as a module so long as when the feature is needed, the
116is left to the reader as a fun exercise however). 118correct module(s) are loaded (module loading is left to the reader as a fun
119exercise however).
117</p> 120</p>
121
118<pre caption="Network Options"> 122<pre caption="Network Options">
119<i>Networking options ---&gt;</i> 123Networking options ---&gt;
120<i> [*] TCP/IP networking</i> 124 [*] TCP/IP networking
121<i> [*] IP: advanced router</i> 125 [*] IP: advanced router
122<i> [*] Network packet filtering (replaces ipchains)</i> 126 [*] Network packet filtering (replaces ipchains)
127<comment>If you use 2.4.x, you have to enable the following for DHCP:</comment>
128 [*] Socket Filtering
123 129
124<i> IP: Netfilter Configuration ---&gt;</i> 130 IP: Netfilter Configuration ---&gt;
125<i> [*] Connection tracking (required for masq/NAT)</i> 131 [*] Connection tracking (required for masq/NAT)
126<i> [x] FTP protocol support</i> 132 [x] FTP protocol support
127<i> [x] IRC protocol support</i> 133 [x] IRC protocol support
128<i> [*] IP tables support (required for filtering/masq/NAT)</i> 134 [*] IP tables support (required for filtering/masq/NAT)
129<i> [*] IP range match support</i> 135 [*] IP range match support
130<i> [x] MAC address match support</i> 136 [x] MAC address match support
131<i> [*] Multiple port match support</i> 137 [*] Multiple port match support
132<i> [*] Packet filtering</i> 138 [*] Packet filtering
133<i> [*] REJECT target support</i> 139 [*] REJECT target support
134<i> [x] REDIRECT target support</i> 140 [x] REDIRECT target support
135<i> [*] Full NAT</i> 141 [*] Full NAT
136<i> [*] MASQUERADE target support</i> 142 [*] MASQUERADE target support
137<i> [s] Packet mangling</i> 143 [s] Packet mangling
138<i> [s] MARK target support</i> 144 [s] MARK target support
139<i> [x] LOG target support</i> 145 [x] LOG target support
140 146
141<i> QoS and/or fair queueing ---&gt;</i> 147 QoS and/or fair queueing ---&gt;
142<i> [s] QoS and/or fair queueing</i> 148 [s] QoS and/or fair queueing
143<i> [s] HTB packet scheduler</i> 149 [s] HTB packet scheduler
144<i> [s] Ingress Qdisc</i> 150 [s] Ingress Qdisc
151
152 [a] PPP (point-to-point protocol) support
153 [a] PPP filtering
154 [a] PPP support for async serial ports
155 [a] PPP support for sync tty ports
156 [a] PPP Deflate compression
157 [a] PPP BSD-Compress compression
158 [a] PPP over Ethernet
145</pre> 159</pre>
160
146<note> 161<note>
147Somethings may be slightly different in a 2.4 vs 2.6 kernel, but you 162Somethings may be slightly different in a 2.4 vs 2.6 kernel, but you should be
148should be able to figure it out :). 163able to figure it out :).
149</note> 164</note>
150 165
151</body> 166</body>
152</section> 167</section>
153</chapter> 168</chapter>
156<title>Hug the WAN (a.k.a. The Internet)</title> 171<title>Hug the WAN (a.k.a. The Internet)</title>
157 172
158<section> 173<section>
159<title>Intro</title> 174<title>Intro</title>
160<body> 175<body>
176
161<p> 177<p>
162There are many ways to connect to the internet so I'll just cover the 178There are many ways to connect to the internet so I'll just cover the ones I'm
163ones I'm familiar with. That leaves us with ADSL (PPPoE) and cable 179familiar with. That leaves us with ADSL (PPPoE) and cable modems
164modems (static/dynamic). If there are other methods out there, feel 180(static/dynamic). If there are other methods out there, feel free to write up
165free to write up a little blurb and e-mail me. Feel free to skip any of 181a little blurb and e-mail me. Feel free to skip any of the following sections
166the following sections in this chapter that don't apply to you. This 182in this chapter that don't apply to you. This chapter is just about getting
167chapter is just about getting the router connected to the internet via 183the router connected to the internet via eth1.
168eth1.
169</p> 184</p>
170</body>
171</section>
172 185
186</body>
187</section>
173<section> 188<section>
174<title>ADSL and PPPoE</title> 189<title>ADSL and PPPoE</title>
175<body> 190<body>
176 191
177<p> 192<p>
178All the fancy PPPoE software has been bundled up into one little nice 193All the fancy PPPoE software has been bundled up into one little nice package
179package nowadays called <uri link="http://www.roaringpenguin.com/">Roaring Penguin</uri>. 194nowadays called <uri link="http://www.roaringpenguin.com/">Roaring
180Simply <c>emerge rp-pppoe</c> and you'll be on your way. Remember how 195Penguin</uri>. Simply <c>emerge rp-pppoe</c> and you'll be on your way.
181I said you'll need username/password information? Well I wasn't lying 196Remember how I said you'll need username/password information? Well I wasn't
182so I hope you have it now! Load up <path>/etc/ppp/pppoe.conf</path> in 197lying so I hope you have it now! Load up <path>/etc/ppp/pppoe.conf</path> in
183your favorite editor and set it up. 198your favorite editor and set it up.
184</p> 199</p>
185 200
186<note> 201<note>
187In order for the following net.eth1 settings to work, you must have 202In order for the following net settings to work, you must have
188baselayout-1.10.1 or later installed on your system. 203baselayout-1.11.14 or later installed on your system.
189</note> 204</note>
190 205
191<pre caption="Setting up eth1"> 206<pre caption="Setting up eth1">
192<comment>(Replace 'vla9h924' with your username and 'password' with your password)</comment> 207<comment>(Replace 'vla9h924' with your username and 'password' with your password)</comment>
193 208
194# <i>nano /etc/ppp/pppoe.conf</i>
195<comment># Ethernet card connected to ADSL modem
196ETH=eth1
197# ADSL user name.
198USER=vla9h924</comment>
199# <i>nano /etc/ppp/pap-secrets</i> 209# <i>nano /etc/ppp/pap-secrets</i>
200<comment># client server secret 210<comment># client server secret</comment>
201"vla9h924" * "password"</comment> 211"vla9h924" * "password"
202# <i>nano /etc/conf.d/net</i> 212# <i>nano /etc/conf.d/net</i>
203<comment>Add an entry for ifconfig_eth1 and set it to adsl: 213<comment>Tell baselayout to use adsl for your eth1:</comment>
204ifconfig_eth1=( "adsl" )</comment> 214config_eth1=( "adsl" )
215user_eth1=( "vla9h924" )
205# <i>ln -s net.eth0 /etc/init.d/net.eth1</i> 216# <i>ln -s net.lo /etc/init.d/net.eth1</i>
206# <i>rc-update add net.eth1 default</i> 217# <i>rc-update add net.eth1 default</i>
207# <i>/etc/init.d/net.eth1 start</i> 218# <i>/etc/init.d/net.eth1 start</i>
208</pre> 219</pre>
209 220
210<warn> 221<warn>
211When the DSL interface comes up, it will create ppp0. Although your NIC 222When the DSL interface comes up, it will create ppp0. Although your NIC is
212is called eth1, the IP is actually bound to ppp0. From now on, when you 223called eth1, the IP is actually bound to ppp0. From now on, when you see
213see examples that utilize 'eth1', substitute with 'ppp0'. 224examples that utilize 'eth1', substitute with 'ppp0'.
214</warn> 225</warn>
215 226
216</body> 227</body>
217</section> 228</section>
218 229
228 239
229<pre caption="Setting up eth1"> 240<pre caption="Setting up eth1">
230<comment>Dynamic IP Users:</comment> 241<comment>Dynamic IP Users:</comment>
231# <i>emerge dhcpcd</i> 242# <i>emerge dhcpcd</i>
232# <i>nano /etc/conf.d/net</i> 243# <i>nano /etc/conf.d/net</i>
233<comment>You'll need an entry like so: 244<comment>You'll need an entry like so:</comment>
234ifconfig_eth1=( "dhcp" )</comment> 245config_eth1=( "dhcp" )
235 246
236<comment>Static IP Users:</comment> 247<comment>Static IP Users:</comment>
237# <i>nano /etc/conf.d/net</i> 248# <i>nano /etc/conf.d/net</i>
238<comment>You'll need entries like so: 249<comment>You'll need entries like so:</comment>
239ifconfig_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" ) 250config_eth1=( "66.92.78.102 broadcast 66.92.78.255 netmask 255.255.255.0" )
240routes_eth1=( "default gw 66.92.78.1" )</comment> 251routes_eth1=( "default gw 66.92.78.1" )
241# <i>nano /etc/resolv.conf</i> 252# <i>nano /etc/resolv.conf</i>
242<comment>Add one line per DNS server: 253<comment>Add one line per DNS server:</comment>
243nameserver 123.123.123.123</comment> 254nameserver 123.123.123.123
244 255
245<comment>Dynamic and Static Setup:</comment> 256<comment>Dynamic and Static Setup:</comment>
246# <i>ln -s net.eth0 /etc/init.d/net.eth1</i> 257# <i>ln -s net.lo /etc/init.d/net.eth1</i>
247# <i>rc-update add net.eth1 default</i> 258# <i>rc-update add net.eth1 default</i>
248# <i>/etc/init.d/net.eth1 start</i> 259# <i>/etc/init.d/net.eth1 start</i>
249</pre> 260</pre>
250 261
251<p> 262<p>
265This step is a breeze compared to the previous one. 276This step is a breeze compared to the previous one.
266</p> 277</p>
267 278
268<pre caption="Setting up eth0"> 279<pre caption="Setting up eth0">
269# <i>nano /etc/conf.d/net</i> 280# <i>nano /etc/conf.d/net</i>
270<comment>Add a line like the following: 281<comment>Add a line like the following:</comment>
271ifconfig_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )</comment> 282config_eth0=( "192.168.0.1 broadcast 192.168.0.255 netmask 255.255.255.0" )
272# <i>rc-update add net.eth0 default</i> 283# <i>rc-update add net.eth0 default</i>
273# <i>/etc/init.d/net.eth0 start</i> 284# <i>/etc/init.d/net.eth0 start</i>
274</pre> 285</pre>
275 286
276</body> 287</body>
281<title>LAN Services (because we're nice people)</title> 292<title>LAN Services (because we're nice people)</title>
282 293
283<section> 294<section>
284<title>DHCP Server</title> 295<title>DHCP Server</title>
285<body> 296<body>
297
286<p> 298<p>
287I bet it'd be nice if everyone else in your house could just plug 299I bet it'd be nice if everyone else in your house could just plug their
288their computers into the network and things would just work. No need to 300computers into the network and things would just work. No need to remember
289remember mind-numbing details or make them stare at confusing 301mind-numbing details or make them stare at confusing configuration screens!
290configuration screens! Life would be grand eh? Introducing the Dynamic 302Life would be grand eh? Introducing the Dynamic Host Configuration Protocol
291Host Configuration Protocol (DHCP) and why you should care. 303(DHCP) and why you should care.
292</p> 304</p>
293 305
294<p> 306<p>
295DHCP is exactly what its name implies. It's a protocol that allows you 307DHCP is exactly what its name implies. It's a protocol that allows you
296to dynamically configure other hosts automatically. You run a DHCP 308to dynamically configure other hosts automatically. You run a DHCP server on
297server on the router (dhcpd), give it all the information about your 309the router, give it all the information about your network (valid IPs,
298network (valid IPs, DNS servers, gateways, etc...), and then when the 310DNS servers, gateways, etc...), and then when the other hosts start up, they
299other hosts start up, they run a DHCP client to automatically configure 311run a DHCP client to automatically configure themselves. No fuss, no muss!
300themselves. No fuss, no muss! For more information about DHCP, you can 312For more information about DHCP, you can always visit <uri
301always visit <uri link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>. 313link="http://en.wikipedia.org/wiki/DHCP">Wikipedia</uri>.
302</p>
303
304<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:
308authoritative;
309subnet 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> 314</p>
326Now your little router is a bona-fide DHCP server! Plugin those 315
327computers and watch them work! With Windows systems you should go into
328the TCP/IP Properties and select the 'Obtain an IP address
329automatically' and 'Obtain DNS server address automatically' options.
330Sometimes the changes aren't instantaneous, so you may have to run a
331command prompt and run <c>ipconfig /release</c> and <c>ipconfig
332/renew</c>. But enough about Windows, let's get back to our favorite
333penguin.
334</p> 316<p>
335</body> 317We'll use a package called dnsmasq which provides both DHCP and DNS services.
336</section> 318For now lets just focus on the DHCP aspect. Note that if you want to run a
337 319different DHCP server, you can find another example in the Fun Things chapter.
338<section> 320Also, if you wish to tinker with the DHCP server settings, just read the
339<title>DNS Server</title> 321comments in <path>/etc/dnsmasq.conf</path>. All the defaults should work fine
340<body> 322though.
341<p> 323</p>
342When people want to visit a place on the internet, they remember names,
343not a string of useless numbers. After all, what's easier to remember,
344ebay.com or 66.135.192.87? This is where the DNS steps in. DNS servers
345run all over the internet, and whenever someone wants to visit 'ebay.com',
346these servers turn 'ebay.com' (what we understand) into '66.135.192.87'
347(what our computers understand). For more information about DNS, you can
348always visit <uri link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
349</p>
350 324
351<p>
352You may have noticed in the previous section that we told the DHCP
353clients we have a DNS server at 192.168.0.1. You may also remember that
354192.168.0.1 is our little router that we're making. I don't remember
355setting up a DNS server ... so let's do so now!
356</p>
357
358<pre caption="Setting up dnsmasq"> 325<pre caption="Setting up a DHCP server">
359# <i>emerge dnsmasq</i> 326# <i>emerge dnsmasq</i>
360# <i>nano /etc/conf.d/dnsmasq</i> 327# <i>nano /etc/dnsmasq.conf</i>
361<comment>Add "-i eth1" to DNSMASQ_OPTS</comment> 328<comment>Add this line to enable dhcp:</comment>
329dhcp-range=192.168.0.100,192.168.0.250,72h
330<comment>Restrict dnsmasq to just the LAN interface</comment>
331interface=eth0
332
362# <i>rc-update add dnsmasq default</i> 333# <i>rc-update add dnsmasq default</i>
363# <i>/etc/init.d/dnsmasq start</i> 334# <i>/etc/init.d/dnsmasq start</i>
364</pre> 335</pre>
365 336
366<p> 337<p>
367Well that was quick, but what did we do? The great thing is, we didn't 338Now your little router is a bona-fide DHCP server! Plugin those computers and
368have to do very much! You're welcome to choose other DNS servers if 339watch them work! With Windows systems you should go into the TCP/IP Properties
369you're more comfortable with them, but the reason dnsmasq is great is 340and select the 'Obtain an IP address automatically' and 'Obtain DNS server
370because it was designed to do exactly what we want and nothing more. 341address automatically' options. Sometimes the changes aren't instantaneous, so
371It's a little DNS caching/forwarding server for local networks. We're 342you may have to open a command prompt and run <c>ipconfig /release</c> and
372not looking to provide DNS for our own domain here, just offer simple DNS 343<c>ipconfig /renew</c>. But enough about Windows, let's get back to our
344favorite penguin.
345</p>
346
347</body>
348</section>
349
350<section>
351<title>DNS Server</title>
352<body>
353
354<p>
355When people want to visit a place on the internet, they remember names, not a
356string of funky numbers. After all, what's easier to remember, ebay.com or
35766.135.192.87? This is where the DNS steps in. DNS servers run all over the
358internet, and whenever someone wants to visit 'ebay.com', these servers turn
359'ebay.com' (what we understand) into '66.135.192.87' (what our computers
360understand). For more information about DNS, you can always visit <uri
361link="http://en.wikipedia.org/wiki/DNS">Wikipedia</uri>.
362</p>
363
364<p>
365Since we're using dnsmasq for our DHCP server, and it includes a DNS server,
366you've got nothing left to do here! Your little router is already providing
367DNS to its DHCP clients. Bet you wish everything was this easy ;).
368</p>
369
370<p>
371You're welcome to choose other DNS servers if you're more comfortable with
372them, but the reason dnsmasq is great is because it was designed to do exactly
373what we want and nothing more. It's a little DNS caching/forwarding server for
374local networks. We're not looking to provide DNS for our own domain here, just
373services to everyone else on our LAN. 375offer simple DNS services to everyone else on our LAN.
374</p> 376</p>
375 377
376</body> 378</body>
377</section> 379</section>
378 380
379<section> 381<section>
380<title>NAT (a.k.a. IP-masquerading)</title> 382<title>NAT (a.k.a. IP-masquerading)</title>
381<body> 383<body>
382 384
383<p> 385<p>
384At this point, people on your network can talk to each other and they 386At this point, people on your network can talk to each other and they can look
385can look up hostnames via DNS, but they still can't actually connect to 387up hostnames via DNS, but they still can't actually connect to the internet.
386the internet. While you may think that's great (more bandwidth for 388While you may think that's great (more bandwidth for you!), I bet they're not
387you!), I bet they're not too happy just yet. 389too happy just yet.
388</p>
389
390<p> 390</p>
391This is where NAT steps in. NAT is a way of connecting multiple computers 391
392in a private LAN to the internet when you only have a smaller number of 392<p>
393IP addresses availabe to you. Typically you were given 1 IP by your ISP, 393This is where Network Address Translation (NAT) steps in. NAT is a way of
394connecting multiple computers in a private LAN to the internet when you have a
395smaller number of public IP addresses available to you. Typically you are given
394but you want to let your whole house connect to the internet. NAT is the 3961 IP by your ISP, but you want to let your whole house connect to the internet.
395magic that makes this possible. For more information about NAT, you can 397NAT is the magic that makes this possible. For more information about NAT, you
396always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>. 398can always visit <uri link="http://en.wikipedia.org/wiki/NAT">Wikipedia</uri>.
397</p> 399</p>
398 400
399<note> 401<note>
400Before we get started, make sure you have iptables on your system. Although 402Before we get started, make sure you have iptables on your system. Although it
401it is automatically installed on most systems, you may not have it. If you 403is automatically installed on most systems, you may not have it. If you don't,
402don't, just run <c>emerge iptables</c>. 404just run <c>emerge iptables</c>.
403</note> 405</note>
404 406
405<pre caption="Setting up iptables"> 407<pre caption="Setting up iptables">
406<comment>First we flush our current rules</comment> 408<comment>First we flush our current rules</comment>
407# <i>iptables -F</i> 409# <i>iptables -F</i>
408# <i>iptables -t nat -F</i> 410# <i>iptables -t nat -F</i>
409 411
412<comment>Setup default policies to handle unmatched traffic</comment>
413# <i>iptables -P INPUT ACCEPT</i>
414# <i>iptables -P OUTPUT ACCEPT</i>
415# <i>iptables -P FORWARD DROP</i>
416
417<comment>Copy and paste these examples ...</comment>
418# <i>export LAN=eth0</i>
419# <i>export WAN=eth1</i>
420
410<comment>Then we lock our services so they only work from the LAN</comment> 421<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> 422# <i>iptables -I INPUT 1 -i ${LAN} -j ACCEPT</i>
412# <i>iptables -I INPUT 1 -i lo -j ACCEPT</i> 423# <i>iptables -I INPUT 1 -i lo -j ACCEPT</i>
413# <i>iptables -A INPUT -p UDP --dport bootps -i ! eth0 -j REJECT</i> 424# <i>iptables -A INPUT -p UDP --dport bootps -i ! ${LAN} -j REJECT</i>
414# <i>iptables -A INPUT -p UDP --dport domain -i ! eth0 -j REJECT</i> 425# <i>iptables -A INPUT -p UDP --dport domain -i ! ${LAN} -j REJECT</i>
426
427<comment>(Optional) Allow access to our ssh server from the WAN</comment>
428# <i>iptables -A INPUT -p TCP --dport ssh -i ${WAN} -j ACCEPT</i>
415 429
416<comment>Drop TCP / UDP packets to privileged ports</comment> 430<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> 431# <i>iptables -A INPUT -p TCP -i ! ${LAN} -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> 432# <i>iptables -A INPUT -p UDP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP</i>
419 433
420<comment>Finally we add the rules for NAT</comment> 434<comment>Finally we add the rules for NAT</comment>
421# <i>iptables -I FORWARD -i eth0 -d 192.168.0.0/255.255.0.0 -j DROP</i> 435# <i>iptables -I FORWARD -i ${LAN} -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> 436# <i>iptables -A FORWARD -i ${LAN} -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> 437# <i>iptables -A FORWARD -i ${WAN} -d 192.168.0.0/255.255.0.0 -j ACCEPT</i>
424# <i>iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE</i> 438# <i>iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE</i>
425<comment>Tell the kernel that ip forwarding is OK</comment> 439<comment>Tell the kernel that ip forwarding is OK</comment>
426# <i>echo 1 > /proc/sys/net/ipv4/ip_forward</i> 440# <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> 441# <i>for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done</i>
428 442
429<comment>This is so when we boot we don't have to run the rules by hand</comment> 443<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> 444# <i>/etc/init.d/iptables save</i>
431# <i>rc-update add iptables default</i> 445# <i>rc-update add iptables default</i>
432# <i>nano /etc/sysctl.conf</i> 446# <i>nano /etc/sysctl.conf</i>
433<comment>Add/Uncomment the following lines: 447<comment>Add/Uncomment the following lines:</comment>
434net.ipv4.ip_forward = 1 448net.ipv4.ip_forward = 1
435net.ipv4.conf.default.rp_filter = 1</comment> 449net.ipv4.conf.default.rp_filter = 1
436</pre>
437 450
451<comment>If you have a dynamic internet address you probably want to enable this:</comment>
452net.ipv4.ip_dynaddr = 1
453</pre>
454
438<p> 455<p>
439Once you've typed out all of that, the rest of your network should now 456Once you've typed out all of that, the rest of your network should now be able
440be able to use the internet as if they were directly connected 457to use the internet as if they were directly connected themselves.
441themselves. 458</p>
459
460<p>
461The ip_dynaddr option is useful for dial on demand systems or when your ISP
462gives out dynamic addresses. This works around the problem where a connection
463is attempted before the internet interface is fully setup. Really this just
464provides for a smoother network experience for users behind your router.
442</p> 465</p>
443 466
444</body> 467</body>
445</section> 468</section>
446</chapter> 469</chapter>
449<title>Fun Things (for a rainy day)</title> 472<title>Fun Things (for a rainy day)</title>
450 473
451<section> 474<section>
452<title>Intro</title> 475<title>Intro</title>
453<body> 476<body>
477
454<p> 478<p>
455Believe it or not, you're done :). From here on out, I'll cover a bunch 479Believe it or not, you're done :). From here on out, I'll cover a bunch of
456of common topics that may interest you. Everything in this chapter is 480common topics that may interest you. Everything in this chapter is completely
457completely optional. 481optional.
458</p> 482</p>
483
459</body> 484</body>
460</section> 485</section>
461 486
462<section> 487<section>
463<title>Port Forwarding</title> 488<title>Port Forwarding</title>
464<body> 489<body>
490
465<p> 491<p>
466Sometimes you would like to be able to host services on a computer behind 492Sometimes you would like to be able to host services on a computer behind the
467the router, or just to make your life easier when connecting remotely. 493router, or just to make your life easier when connecting remotely. Perhaps you
468Perhaps you want to run a FTP, HTTP, SSH, or VNC server on one or more 494want to run a FTP, HTTP, SSH, or VNC server on one or more machines behind your
469machines behind your router and be able to connect to them all. The only 495router and be able to connect to them all. The only caveat is that you can
470caveat is that you can only have one service/machine combo per port. 496only have one service/machine combo per port. For example, there is no
471For example, there is no practical way to setup three FTP servers behind 497practical way to setup three FTP servers behind your router and then try to
472your router and then try to connect to them all through port 21; only one 498connect to them all through port 21; only one can be on port 21 while the
473can be on port 21 while the others would have to be on say port 123 and 499others would have to be on say port 123 and port 567.
474port 567.
475</p>
476
477<p> 500</p>
501
502<p>
478All the port forwarding rules are of the form <c>iptables -t nat -A PREROUTING 503All 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 504[-p protocol] --dport [external port on router] -i ${WAN} -j DNAT --to [ip/port
480to forward to]</c>. iptables does not accept hostnames when port forwarding. 505to forward to]</c>. Unfortunately, iptables does not accept hostnames when port
481If you are forwarding an external port to the same port on the internal machine, 506forwarding. If you are forwarding an external port to the same port on the
482you can omit the destination port. See the iptables(8) page for more information. 507internal machine, you can omit the destination port. See the iptables(8) man
508page for more information.
483</p> 509</p>
484 510
485<pre> 511<pre caption="Running the iptables commands">
512<comment>Copy and paste these examples ...</comment>
513# <i>export LAN=eth0</i>
514# <i>export WAN=eth1</i>
515
486<comment>Forward port 2 to ssh on an internal host</comment> 516<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> 517# <i>iptables -t nat -A PREROUTING -p tcp --dport 2 -i ${WAN} -j DNAT --to 192.168.0.2:22</i>
488 518
489<comment>FTP forwarding to an internal host</comment> 519<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> 520# <i>iptables -t nat -A PREROUTING -p tcp --dport 21 -i ${WAN} -j DNAT --to 192.168.0.56</i>
491 521
492<comment>HTTP forwarding to an internal host</comment> 522<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> 523# <i>iptables -t nat -A PREROUTING -p tcp --dport 80 -i ${WAN} -j DNAT --to 192.168.0.56</i>
494 524
495<comment>VNC forwarding for internal hosts</comment> 525<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> 526# <i>iptables -t nat -I PREROUTING -p tcp --dport 5900 -i ${WAN} -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> 527# <i>iptables -t nat -I PREROUTING -p tcp --dport 5901 -i ${WAN} -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> 528<comment>If you want to VNC in to 192.168.0.3, then just add ':1' to the router's hostname</comment>
499 529
500<comment>Bittorrent forwarding</comment> 530<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> 531# <i>iptables -t nat -A PREROUTING -p tcp --dport 6881:6889 -i ${WAN} -j DNAT --to 192.168.0.2</i>
532
533<comment>eDonkey/eMule forwarding</comment>
534# <i>iptables -t nat -A PREROUTING -p tcp --dport 4662 -i ${WAN} -j DNAT --to 192.168.0.55</i>
502 535
503<comment>Game Cube Warp Pipe support</comment> 536<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> 537# <i>iptables -t nat -A PREROUTING -p udp --dport 4000 -i ${WAN} -j DNAT --to 192.168.0.56</i>
505 538
506<comment>Playstation2 Online support</comment> 539<comment>Playstation 2 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> 540# <i>iptables -t nat -A PREROUTING -p tcp --dport 10070:10080 -i ${WAN} -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> 541# <i>iptables -t nat -A PREROUTING -p udp --dport 10070:10080 -i ${WAN} -j DNAT --to 192.168.0.11</i>
542
543<comment>Xbox Live</comment>
544# <i>iptables -t nat -A PREROUTING -p tcp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
545# <i>iptables -t nat -A PREROUTING -p udp --dport 3074 -i ${WAN} -j DNAT --to 192.168.0.69</i>
546# <i>iptables -t nat -A PREROUTING -p udp --dport 88 -i ${WAN} -j DNAT --to 192.168.0.69</i>
509</pre> 547</pre>
510 548
511<note> 549<note>
512If you have other common / cool examples, please <uri link="mailto:vapier@gentoo.org">e-mail me</uri>. 550If you have other common / cool examples, please <mail
551link="vapier@gentoo.org">e-mail me</mail>.
513</note> 552</note>
553
514</body> 554</body>
515</section> 555</section>
516 556
517<section> 557<section>
518<title>Identd (for IRC)</title> 558<title>Identd (for IRC)</title>
519<body> 559<body>
560
520<p> 561<p>
521Internet Relay Chat utilizes the ident service pretty heavily. Now that 562Internet Relay Chat utilizes the ident service pretty heavily. Now that the
522the IRC clients are behind the router, we need a way to host ident for 563IRC clients are behind the router, we need a way to host ident for both the
523both the router and the clients. One such server has been created 564router and the clients. One such server has been created called
524called <c>midentd</c>. 565<c>midentd</c>.
525</p> 566</p>
526 567
527<pre caption="Setting up ident"> 568<pre caption="Setting up ident">
528# <i>emerge midentd</i> 569# <i>emerge midentd</i>
529# <i>rc-update add midentd default</i> 570# <i>rc-update add midentd default</i>
530# <i>/etc/init.d/midentd start</i> 571# <i>/etc/init.d/midentd start</i>
531</pre> 572</pre>
532 573
533<p> 574<p>
534There are a few other ident servers in portage. Depending on your needs, 575There are a few other ident servers in portage. Depending on your needs, I
535I would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>. 576would recommend checking out <c>oidentd</c> and <c>fakeidentd</c>.
536</p> 577</p>
578
537</body> 579</body>
538</section> 580</section>
539 581
540<!-- 582<!--
541<section> 583<section>
611--> 653-->
612 654
613<section> 655<section>
614<title>Time Server</title> 656<title>Time Server</title>
615<body> 657<body>
658
616<p> 659<p>
617Keeping your system time correct is essential in maintaing a healthy 660Keeping your system time correct is essential in maintaining a healthy system.
618system. One of the most common ways of accomplishing this is with 661One of the most common ways of accomplishing this is with the Network Time
619the Network Time Protocol [NTP] and the ntp package (which provides 662Protocol (NTP) and the ntp package (which provides implementations for both
620implementations for both server and client). 663server and client).
621</p>
622
623<p> 664</p>
665
666<p>
624Many people run ntp clients on their computers. Obviously, the more 667Many people run ntp clients on their computers. Obviously, the more clients in
625clients in the world, the larger the load the ntp servers need to 668the world, the larger the load the ntp servers need to shoulder. In
626shoulder. In environments like home networks though, we can help 669environments like home networks though, we can help keep the load down on
627keep the load down on public servers while still providing the proper 670public servers while still providing the proper time to all our computers. As
628time to all our computers. As an added bonus, our private updates 671an added bonus, our private updates will be a lot faster for the clients too!
629will be a lot faster for the clients too! All we have to do is run 672All we have to do is run a ntp server on our router that synchronizes itself
630a ntp server on our router that synchronizes itself with the public
631internet servers while providing the time to the rest of the computers 673with the public internet servers while providing the time to the rest of the
632in the network. To get started, simply <c>emerge ntp</c> on the 674computers in the network. To get started, simply <c>emerge ntp</c> on the
633router. 675router.
634</p> 676</p>
635 677
636<pre caption="Setting up the NTP server"> 678<pre caption="Setting up the NTP server">
637# <i>nano /etc/conf.d/ntp-client</i> 679# <i>nano /etc/conf.d/ntp-client</i>
638<comment>Customize if you wish but the defaults should be fine</comment> 680<comment>Customize if you wish but the defaults should be fine</comment>
639# <i>rc-update add ntp-client default</i> 681# <i>rc-update add ntp-client default</i>
640 682
641# <i>nano /etc/ntp.conf</i> 683# <i>nano /etc/ntp.conf</i>
642<comment>Add the follwing lines: 684<comment>Add the follwing lines:</comment>
643restrict default ignore 685restrict default ignore
644restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap 686restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
645These will allow only ntp clients with an IP address in the 192.168.0.xxx range to use your ntp server</comment> 687<comment>These will allow only ntp clients with an IP
688address in the 192.168.0.xxx range to use your ntp server</comment>
646# <i>nano /etc/conf.d/ntpd</i> 689# <i>nano /etc/conf.d/ntpd</i>
647<comment>Customize if you wish but the defaults should be fine</comment> 690<comment>Customize if you wish but the defaults should be fine</comment>
691# <i>rc-update add ntpd default</i>
648 692
649# <i>/etc/init.d/ntp-client start</i> 693# <i>/etc/init.d/ntp-client start</i>
650# <i>/etc/init.d/ntpd start</i> 694# <i>/etc/init.d/ntpd start</i>
651</pre> 695</pre>
652 696
697<note>
698You should make sure that you allow inbound and outbound communication on the
699ntp port (123/udp) when setting up the server. The client just needs outbound
700access on port 123 over udp.
701</note>
702
653<p> 703<p>
654Now, on your clients, have them <c>emerge ntp</c> also. However, 704Now, on your clients, have them <c>emerge ntp</c> also. However, we will just
655we will just run the ntp client so setup is a lot simpler. 705run the ntp client so setup is a lot simpler.
656</p> 706</p>
657 707
658<pre caption="Setting up a NTP client"> 708<pre caption="Setting up a NTP client">
659# <i>nano /etc/conf.d/ntp-client</i> 709# <i>nano /etc/conf.d/ntp-client</i>
660<comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment> 710<comment>Change the 'pool.ntp.org' server in the NTPCLIENT_OPTS variable to '192.168.0.1'</comment>
661# <i>rc-update add ntp-client default</i> 711# <i>rc-update add ntp-client default</i>
662# <i>/etc/init.d/ntp-client start</i> 712# <i>/etc/init.d/ntp-client start</i>
663</pre> 713</pre>
714
715</body>
716</section>
717
718<section>
719<title>Rsync Server</title>
720<body>
721
722<p>
723For those who run multiple Gentoo boxes on the same lan, you often want to
724keep from having every machine running <c>emerge sync</c> with remote
725servers. By setting up a local rsync, you save on both your bandwidth and
726the Gentoo rsync servers' bandwidth. It's pretty simple to do.
727</p>
728
729<note>
730For a much more in-depth rsync guide, please see the official <uri
731link="/doc/en/rsync.xml#local">rsync guide</uri>.
732</note>
733
734<p>
735Since every Gentoo machine requires rsync, theres no need to emerge it. Edit
736the default <path>/etc/rsyncd.conf</path> config file, uncomment the
737<c>[gentoo-portage]</c> section, and make sure you add an <c>address</c>
738option. All the other defaults should be fine.
739</p>
740
741<pre caption="Rsync server config">
742pid file = /var/run/rsyncd.pid
743use chroot = yes
744read only = yes
745address = 192.168.0.1
746
747[gentoo-portage]
748 path = /mnt/space/portage
749 comment = Gentoo Linux Portage tree
750 exclude = /distfiles /packages
751</pre>
752
753<p>
754Then you need to start the service (again, the defaults are OK).
755</p>
756
757<pre caption="Starting the rsync server">
758# <i>/etc/init.d/rsyncd start</i>
759# <i>rc-update add rsyncd default</i>
760</pre>
761
762<p>
763Only thing left is to set tell your clients to sync against the router.
764</p>
765
766<pre caption="Client SYNC settings in make.conf">
767SYNC="rsync://192.168.0.1/gentoo-portage"
768</pre>
769
664</body> 770</body>
665</section> 771</section>
666 772
667<section> 773<section>
668<title>Mail Server</title> 774<title>Mail Server</title>
669<body> 775<body>
776
670<p> 777<p>
671Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP) 778Sometimes it's nice to run your own Simple Mail Transfer Protocol (SMTP) server
672server on the router. You may have your own reason for wanting to do so, 779on the router. You may have your own reason for wanting to do so, but I run it
673but I run it so that the users see mail as being sent instantly and the 780so that the users see mail as being sent instantly and the work of
674work of retrying/routing is left up to the mail server. Some ISPs also 781retrying/routing is left up to the mail server. Some ISPs also don't allow for
675don't allow for mail relaying for accounts that aren't part of their 782mail relaying for accounts that aren't part of their network (like Verizon).
676network (like Verizon). Also, you can easily throttle the delivery of 783Also, you can easily throttle the delivery of mail so that large attachments
677mail so that large attachments won't seriously lag your connection for 784won't seriously lag your connection for half an hour.
678half an hour.
679</p> 785</p>
680 786
681<pre caption="Setting up SMTP"> 787<pre caption="Setting up SMTP">
682# <i>emerge qmail</i> 788# <i>emerge qmail</i>
683<comment>make sure the output of `hostname` is correct</comment> 789<comment>make sure the output of `hostname` is correct</comment>
684# <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i> 790# <i>ebuild /var/db/pkg/*-*/qmail-1.03-r*/*.ebuild config</i>
685# <i>iptables -I INPUT -p tcp --dport smtp -i ! eth0 -j REJECT</i> 791# <i>iptables -I INPUT -p tcp --dport smtp -i ! ${LAN} -j REJECT</i>
686# <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i> 792# <i>ln -s /var/qmail/supervise/qmail-send /service/qmail-send</i>
687# <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i> 793# <i>ln -s /var/qmail/supervise/qmail-smtpd /service/qmail-smtpd</i>
688<!-- 794<!--
689# <i>cd /etc/tcprules.d</i> 795# <i>cd /etc/tcprules.d</i>
690# <i>nano tcp.qmail-smtp</i> 796# <i>nano tcp.qmail-smtp</i>
691--> 797-->
692# <i>cd /etc</i> 798# <i>cd /etc</i>
693# <i>nano tcp.smtp</i> 799# <i>nano tcp.smtp</i>
694<comment>Add an entry like so to the allow section: 800<comment>Add an entry like so to the allow section:</comment>
695192.168.0.:allow,RELAYCLIENT=""</comment> 801192.168.0.:allow,RELAYCLIENT=""
696<!-- 802<!--
697# <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i> 803# <i>tcprules tcp.qmail-qmtp.cdb rules.tmp &lt; tcp.qmail-smtp</i>
698--> 804-->
699# <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i> 805# <i>tcprules tcp.smtp.cdb rules.tmp &lt; tcp.smtp</i>
700# <i>rc-update add svscan default</i> 806# <i>rc-update add svscan default</i>
701# <i>/etc/init.d/svscan start</i> 807# <i>/etc/init.d/svscan start</i>
702</pre> 808</pre>
703 809
704<p> 810<p>
705I'm a huge fan of qmail, but you're free to use a different mta :). 811I'm a huge fan of qmail, but you're free to use a different mta :). When you
706When you setup e-mail on the hosts in your network, tell them that 812setup e-mail on the hosts in your network, tell them that their SMTP server is
707their SMTP server is 192.168.0.1 and everything should be peachy. 813192.168.0.1 and everything should be peachy. You might want to visit the <uri
708You might want to visit the <uri link="http://qmail.org/">qmail 814link="http://qmail.org/">qmail homepage</uri> for more documentation.
709homepage</uri> for more documentation.
710</p> 815</p>
816
711</body> 817</body>
712</section> 818</section>
713 819
714<!-- 820<!--
715<section> 821<section>
728 834
729</body> 835</body>
730</section> 836</section>
731--> 837-->
732 838
839<section>
840<title>Full DHCP Server</title>
841<body>
842
843<p>
844Earlier we used dnsmasq to provide DHCP service to all our clients. For most
845people with a simple small LAN, this is perfect. But you may need something
846with more features. Thus we turn to a full-featured DHCP server as provided
847by the <uri link="http://www.isc.org/products/DHCP">ISC</uri> folks.
848</p>
849
850<pre caption="Setting up dhcpd">
851# <i>emerge dhcp</i>
852# <i>nano /etc/dhcp/dhcpd.conf</i>
853<comment>(Here is a sample configuration file:)</comment>
854authoritative;
855ddns-update-style interim;
856subnet 192.168.0.0 netmask 255.255.255.0 {
857 range 192.168.0.100 192.168.0.250;
858 default-lease-time 259200;
859 max-lease-time 518400;
860 option subnet-mask 255.255.255.0;
861 option broadcast-address 192.168.0.255;
862 option routers 192.168.0.1;
863 option domain-name-servers 192.168.0.1;
864}
865# <i>nano /etc/conf.d/dhcpd</i>
866<comment>(Set IFACE="eth0")</comment>
867# <i>rc-update add dhcpd default</i>
868# <i>/etc/init.d/dhcpd start</i>
869</pre>
870
871<p>
872This is the minimal setup required to replace the dnsmasq DHCP functionality
873that we used earlier. Speaking of which, you did remember to disable the DHCP
874features in dnsmasq didn't you? If not, you should do so now (just comment
875out the <c>dhcp-range</c> setting in <path>/etc/dnsmasq.conf</path> and restart
876the service).
877</p>
878
879</body>
880</section>
881
882<section>
883<title>Connect Another LAN (or two or three or ...)</title>
884<body>
885
886<p>
887Sometimes you have need of connecting the router to another LAN. Maybe you
888want to hook up a group of friends temporarily, or you're a neat freak and
889want to section off different groups of computers, or you're just really
890really bored. Whatever the reasons, extending the router to other LAN
891networks should be pretty straightforward. In the following examples, I will
892assume that this new network is connected via a third ethernet card, namely
893<c>eth2</c>.
894</p>
895
896<p>
897First you need to configure the interface. Just take the instructions in the
898<uri link="#doc_chap4_pre1">4.1 code listing</uri> and replace <c>eth0</c>
899with <c>eth2</c> and <c>192.168.0</c> with <c>192.168.1</c>.
900</p>
901
902<p>
903Then you need to tweak dnsmasq to service the new interface. Just edit the
904<path>/etc/conf.d/dnsmasq</path> file again and append <c>-i eth2</c> to
905DNSMASQ_OPTS; using -i multiple times is OK. Then edit
906<path>/etc/dnsmasq.conf</path> and add another line like the dhcp-range line
907in the <uri link="#doc_chap5_pre1">5.1 code listing</uri>, replacing
908<c>192.168.0</c> with <c>192.168.1</c>. Having multiple dhcp-range lines is
909OK too.
910</p>
911
912<p>
913Finally, see the rules in the <uri link="#doc_chap5_pre2">5.2 code
914listing</uri> and duplicate the rules that have <c>-i ${LAN}</c> in them. You
915may want to create another variable, say <c>LAN2</c>, to make things easier.
916</p>
917
918</body>
919</section>
920
921</chapter>
922
923<chapter>
924<title>Troubleshooting</title>
925
926<section>
927<title>Useful Tools</title>
928<body>
929
930<p>
931If you're having trouble getting your computers to communicate, you may way to
932try out the following tools (they can all be found in the <c>net-analyzer</c>
933portage category):
934</p>
935
936<table>
937<tr>
938 <th>Utility</th>
939 <th>Description</th>
940</tr>
941<tr>
942 <ti>ethereal</ti>
943 <ti>GUI tool to view all raw network data according to filters</ti>
944</tr>
945<tr>
946 <ti>tcpdump</ti>
947 <ti>Console tool to dump all raw network data according to filters</ti>
948</tr>
949<tr>
950 <ti>iptraf</ti>
951 <ti>ncurses based IP LAN monitor</ti>
952</tr>
953<tr>
954 <ti>ettercap</ti>
955 <ti>ncurses based network monitor/control</ti>
956</tr>
957</table>
958
959</body>
960</section>
961
962<section>
963<title>DHCP Fails To Start</title>
964<body>
965
966<p>
967When starting the dhcp init.d script for the first time, it may fail to load
968but neglect to give you any useful info.
969</p>
970
971<pre caption="DHCP Failing Example">
972# <i>/etc/init.d/dhcp start</i>
973 * Setting ownership on dhcp.leases ... [ ok ]
974 * Starting dhcpd ... [ !! ]
975</pre>
976
977<p>
978The trick is to know where dhcpd is sending its output. Simply browse to
979<path>/var/log</path> and read the log files. Since the exact log file depends
980on the package you are using as a syslog, try running <c>grep -Rl dhcpd
981/var/log</c> to narrow down the possibilities. Chances are you made a typo in
982your config file. You could also try running <c>dhcpd -d -f</c> (short for
983debug / foreground) and debug the error based upon the output.
984</p>
985
986</body>
987</section>
988
989<section>
990<title>Incorrect MTU Value</title>
991<body>
992
993<p>
994If you experience odd errors (such as not being some webpages while others
995load fine), you may be having Path MTU Discovery trouble. The quick way to
996test is to run this iptables command:
997</p>
998
999<pre caption="Circumvent MTU issues">
1000# <i>iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu</i>
1001</pre>
1002
1003<p>
1004This will affect all new connections, so just refresh the website you're
1005having problems with in order to test. In case it helps, the standard MTU
1006value for 100mbit ethernet connections is <c>1500</c> while for PPPoE
1007connections it is <c>1492</c>. For more info, you should read Chapter 15
1008of the <uri link="http://lartc.org/howto/">Linux Advanced Routing &amp;
1009Traffic Control HOWTO</uri>.
1010</p>
1011
1012</body>
1013</section>
1014
1015<section>
1016<title>Unable to connect two machines directly</title>
1017<body>
1018
1019<p>
1020If (for whatever reason) you want to connect two machines directly together
1021without a hub or switch, a regular ethernet cable will likely not work, unless
1022you have an Auto MDI/MDI-X (also known as "autosensing") capable network
1023adapter. You will need a different cable called a crossover cable. This <uri
1024link="http://en.wikipedia.org/wiki/Ethernet_crossover_cable">Wikipedia</uri>
1025page explains the low level details.
1026</p>
1027
1028</body>
1029</section>
1030
733</chapter> 1031</chapter>
734 1032
735<chapter> 1033<chapter>
736<title>Final Notes</title> 1034<title>Final Notes</title>
737<section> 1035<section>
738<body> 1036<body>
1037
739<p> 1038<p>
740I have no final notes other than if you experience any troubles with the guide, 1039I have no final notes other than if you experience any troubles with the guide,
741please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with 1040please contact <mail link="vapier@gentoo.org">me</mail> or file a bug with <uri
742<uri link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If 1041link="http://bugs.gentoo.org/">Gentoo's Bugtracking Website</uri>. If you have
743you have some interesting bits you think would enhance this guide, by all means 1042some interesting bits you think would enhance this guide, by all means send it
744send it my way for inclusion. 1043my way for inclusion.
745</p> 1044</p>
1045
746</body> 1046</body>
747</section> 1047</section>
748</chapter> 1048</chapter>
749</guide> 1049</guide>

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