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+<?xml version="1.0"?>
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "/usr/share/xml/docbook/xml-dtd-4.5/docbookx.dtd">
+
+<chapter>
+<title>Networking</title>
+
+<section>
+<title><application>netconfig</application></title>
+
+<para>
+Computers aren't very interesting on their own. Sure, you can install
+games on them, but that just turns them into glorified entertainment
+consoles. Today, computers need to be able to talk to one another; they
+need to be networked. Whether you're installing a business network with
+hundreds or thousands of computers or just setting up a single PC for
+Internet access, Slackware is simple and easy. This chapter should
+teach you how to setup typical wired networks. Common wireless setup will
+be thoroughly discussed in the next section, but much of what you read
+here will be applicable there as well.
+</para>
+
+<para>
+There are many different ways to configure your computer to connect to
+a network or the Internet, but they fall into two main categories:
+static and dymanic. Static addresses are solid; they are set with the
+understanding that they will not be changed, at least not anytime soon.
+Dynamic addresses are fluid; the assumption is that the address will
+change at some time in the future. Typically any sort of network server
+requires a static address simply so other machines will know where to
+contact it when they need services. Dynamic addresses tend to be used
+for workstations, Internet clients, and any machine that doesn't
+require a static address for any reason. Dynamic addresses are more
+flexible, but present complications of their own.
+</para>
+
+<para>
+There are many different kinds of network protocols that you might
+encounter, but most people will only ever need to deal with Internet
+Protocol (IP). For that reason, we'll focus exclusively on IP in this
+book.
+</para>
+
+</section>
+
+<section>
+<title>Manual Configuration</title>
+
+<para>
+Ok, so you've installed Slackware, you've setup a desktop, but you
+can't get it to connect to the Internet or your business's LAN (local
+area network), what do you do? Fortunately, the answer to that question
+is simple. Slackware includes a number of tools to configure your
+network connection. The first we will look at today is the very
+powerful <application>ifconfig</application>(8).
+<application>ifconfig</application> is used to setup or modify the
+configuration of a Network Interface Card (NIC or Ethernet Card), the
+most common hardware for connecting to networks today.
+<application>ifconfig</application> is an incredibly powerful tool
+capable of doing much more than setting IP addresses. For a complete
+introduction, you should read its man page. For now, we're just going
+to use it to display and change the network addresses of some ethernet
+controllers.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>ifconfig</userinput>
+lo        Link encap:Local Loopback  
+          inet addr:127.0.0.1  Mask:255.0.0.0
+          inet6 addr: ::1/128 Scope:Host
+          UP LOOPBACK RUNNING  MTU:16436  Metric:1
+          RX packets:699 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:699 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:0 
+          RX bytes:39518 (38.5 KiB)  TX bytes:39518 (38.5 KiB)
+
+wlan0     Link encap:Ethernet  HWaddr 00:1c:b3:ba:ad:4c  
+          inet addr:192.168.1.198  Bcast:192.168.1.255  Mask:255.255.255.0
+          inet6 addr: fe80::21c:b3ff:feba:ad4c/64 Scope:Link
+          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+          RX packets:1630677 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:1183224 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:1627370207 (1.5 GiB)  TX bytes:163308463 (155.7 MiB)
+
+wmaster0  Link encap:UNSPEC  HWaddr 00-1C-B3-BA-AD-4C-00-00-00-00-00-00-00-00-00-00  
+          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
+</screen>
+
+
+<para>
+As you can clearly see here, when run without any arguments,
+<application>ifconfig</application> will display all the information it
+has on all the ethernet cards (and wireless ethernet cards) present on
+your system. The above represents a typical wireless connection from my
+laptop, so don't be afraid if what you see on your system doesn't
+match.  If you don't see any ethX or wlanX interfaces though, the
+interface may be down. To show all currently present NICs whether they are
+"up" or "down", simply pass the <arg>-a</arg> argument.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>ifconfig -a</userinput>
+eth0      Link encap:Ethernet  HWaddr 00:19:e3:45:90:44  
+          UP BROADCAST MULTICAST  MTU:1500  Metric:1
+          RX packets:122780 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:124347 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:60495452 (57.6 MiB)  TX bytes:17185220 (16.3 MiB)
+          Interrupt:16 
+
+lo        Link encap:Local Loopback  
+          inet addr:127.0.0.1  Mask:255.0.0.0
+          inet6 addr: ::1/128 Scope:Host
+          UP LOOPBACK RUNNING  MTU:16436  Metric:1
+          RX packets:699 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:699 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:0 
+          RX bytes:39518 (38.5 KiB)  TX bytes:39518 (38.5 KiB)
+
+wlan0     Link encap:Ethernet  HWaddr 00:1c:b3:ba:ad:4c  
+          inet addr:192.168.1.198  Bcast:192.168.1.255  Mask:255.255.255.0
+          inet6 addr: fe80::21c:b3ff:feba:ad4c/64 Scope:Link
+          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+          RX packets:1630677 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:1183224 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:1627370207 (1.5 GiB)  TX bytes:163308463 (155.7 MiB)
+
+wmaster0  Link encap:UNSPEC  HWaddr 00-1C-B3-BA-AD-4C-00-00-00-00-00-00-00-00-00-00  
+          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
+</screen>
+
+<para>Notice that the eth0 interface is now listed among the returns.
+<application>ifconfig</application> can also change the current
+settings on a NIC. Typically, you would need to change the IP address
+and subnet mask, but you can change virtually any parameters.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>ifconfig eth0 192.168.1.1 netmask 255.255.255.0</userinput>
+<prompt>darkstar:~# </prompt><userinput>ifconfig eth0</userinput>
+eth0      Link encap:Ethernet  HWaddr 00:19:e3:45:90:44  
+          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
+          UP BROADCAST MULTICAST  MTU:1500  Metric:1
+          RX packets:122780 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:124347 errors:0 dropped:0 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000 
+          RX bytes:60495452 (57.6 MiB)  TX bytes:17185220 (16.3 MiB)
+          Interrupt:16 
+</screen>
+
+<para>
+If you look carefully, you'll notice that the interface now has the
+192.168.1.1 IP address and a 255.255.255.0 subnet mask. We've now setup
+the basics for connecting to our network, but we still need to setup a
+default gateway and our DNS servers. In order to do that, we'll need to
+look at a few more tools.
+</para>
+
+<para>
+Next on our stop through networking land is the equally powerful
+<application>route</application>(8). This tool is responsible for
+modifying the Linux kernel's routing table which affects all data
+transmission on a network. Routing tables can become immensely complex
+or they can be straight-forward and simple. Most users will only ever
+need to setup a default gateway, so we'll show you how to do that here.
+If for some reason you need a more complex routing table, you would be
+well advised to read the entire man page for
+<application>route</application> as well as consulting other sources.
+For now, let's take a look at our routing table immediately after
+setting up eth0.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>route</userinput>
+Kernel IP routing table
+Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
+192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
+loopback        *               255.0.0.0       U     0      0        0 lo
+</screen>
+
+<para>
+I won't explain everything here, but the general information should be
+easy to pick up if you're familiar with networking at all. The
+Destination and Genmask fields specify a range of IP addresses to
+match. If a Gateway is defined, information in the form of packets will
+be sent to that host for forwarding. We also specify an interface in
+the final field that the information should traverse. Right now, we can
+only communicate with computers with addresses between 192.168.1.0 and
+192.168.1.255 and ourselves through the loopback interface, a type of
+virtual NIC that is used for routing information from this computer to
+itself.  In order to reach the rest of the world, we'll need to
+setup a default gateway.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>route add default gw 192.168.1.254</userinput>
+<prompt>darkstar:~# </prompt><userinput>route</userinput>
+Kernel IP routing table
+Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
+192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
+loopback        *               255.0.0.0       U     0      0        0 lo
+default         192.168.1.254   0.0.0.0         UG    0      0        0 eth0
+</screen>
+
+<para>
+You should immediately notice the addition of a default route. This
+specifies what router should be used to reach any addresses that aren't
+specified elsewhere in our routing table. Now, when we try to connect
+to say, 64.57.102.34, the information will be sent to 192.168.1.254
+which is responsible for delivering the data for us. Unfortunately,
+we're still not quite through. We need some way of converting domain
+names like slackware.com into IP addresses that the computer can use.
+For that, we need to make use of a DNS server.
+</para>
+
+<para>
+Fortunately, setting up your computer to use an external (or even an
+internal) DNS server is very easy. You'll need to use your favorite
+text editor and open the <filename>/etc/resolv.conf</filename> file.
+Don't ask me what happened to the <keycap>e</keycap>. On my computer,
+<filename>resolv.conf</filename> looks like this.
+</para>
+
+<screen>
+# /etc/resolv.conf
+search lizella.net
+nameserver 192.168.1.254
+</screen>
+
+<para>
+Most users won't need the "search" line. This is used to map hostnames
+to domain names. Basically, if I attempt to connect to "barnowl", the
+computer knows to look for "barnowl.lizella.net" thanks to this search
+line. We're mainly interested in the "nameserver" line. This tells
+Slackware what domain name servers (DNS) to connect to. Generally
+speaking, these should always be specified by IP address. If you know
+what DNS servers you should use, you can just add them one at a time to
+individual nameserver lines. In fact, I don't know of any practical
+limit to the number of nameservers that can be specified in
+<filename>resolv.conf</filename>, so add as many as you like. Once this
+is done, you should be able to communicate with other hosts via their
+fully qualified domain name.
+</para>
+
+<para>
+But Alan! That's a lot of hard work! I don't want to do this time and
+again for dozens or even hundreds of machines. You're absolutely right,
+and that's why smarter people than you and me created DHCP.  DHCP
+stands for Dynamic Host Control Protocol and is a method for
+automatically configuring computers with unique IP addresses, netmasks,
+gateways, and DNS servers. Most of the time, you'll want to use DHCP.
+The majority of wireless routers, DSL or cable modems, even firewalls
+all have DHCP servers to can make your life much easier. Slackware
+includes two main tools for connecting to an exising DHCP server and
+can even act as a DHCP server for other computers. For now though,
+we're just going to look at DHCP clients.
+</para>
+
+<para>
+First on our list is <application>dhcpcd</application>(8), part of the
+ISC DHCP utilities. Assuming your computer is physically connected to
+your network, and that you have an operating DHCP server on that
+network, you can configure your NIC in one shot.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>dhcpcd eth0</userinput>
+</screen>
+
+<para>
+If everything went according to plan, your NIC should be properly
+configured, and you should be able to communicate with other computers
+on your network, and with the Internet at large. If for some reason,
+<application>dhcpcd</application> fails, you may want to try
+<application>dhclient</application>(8).
+<application>dhclient</application> is an alternative to
+<application>dhcpcd</application> and works in basically the same way.
+</para>
+
+<screen><prompt>darkstar:~# </prompt><userinput>dhclient eth0</userinput>
+Listening on LPF/eth0/00:1c:b3:ba:ad:4c
+Sending on   LPF/eth0/00:1c:b3:ba:ad:4c
+Sending on   Socket/fallback
+DHCPREQUEST on eth0 to 255.255.255.255 port 67
+DHCPACK from 192.168.1.254
+bound to 192.168.1.198 -- renewal in 8547 seconds.
+</screen>
+
+<para>
+So why does Slackware include two DHCP clients? Sometimes a particular
+DHCP server may be broken and not respond well to either 
+<application>dhcpcd</application> or
+<application>dhclient</application>. In those cases, you can fall back
+to the other DHCP client in hopes of getting a valid response from the
+server. Traditionally, Slackware uses
+<application>dhcpcd</application>, and this works in the vast majority
+of cases, but it may become necessary at some point for you to use
+<application>dhclient</application> instead. Both are excellent DHCP
+clients, so use whichever you prefer.
+</para>
+
+</section>
+
+<section>
+<title>Automatic Configuration with rc.inet1.conf</title>
+
+<para>
+Manually configuring interfaces is an important skill to have, but it
+can become tedious.  No one wants to manually setup their Internet
+connection every time the system boots.  More importantly, you may not
+always have physical access to the machine when it boots.  Slackware
+makes it easy to automatically configure ethernet (and wireless) cards
+at system startup with <filename>/etc/rc.d/rc.inet1.conf</filename>.
+For now, we're going to focus on traditional wired ethernet networking;
+the next chapter will discuss various wireless options.
+</para>
+
+<para>
+<filename>rc.inet1.conf</filename> is an incredibly powerful
+configuration file, capable of configuring most of your network cards
+automatically when Slackware is started. The file is filled with useful
+comments, but there is also a man page that more thoroughly discusses
+its use.  To begin, we're going to look at some of the options used on
+one of my personal machines.
+</para>
+
+<screen>
+# Config information for eth0:
+IPADDR[0]="192.168.1.250"
+NETMASK[0]="255.255.255.0"
+USE_DHCP[0]=""
+DHCP_HOSTNAME[0]=""
+# Some lines ommitted.
+GATEWAY="192.168.1.254"
+</screen>
+
+<para>
+This represents most of the information necessary to configure a static
+IP address on a single ethernet controller.
+<application>netconfig</application> will usually fill in these values 
+for a single ethernet device for you.  If you have multiple network
+cards in your machine and need all of them activated automatically at
+boot time, then you'll need to edit or add additional entries into this
+file in the same manner as above.  First, let me go over some of the
+basics.
+</para>
+
+<para>
+As you may have already guessed, IPADDR[n] is the Internet Protocol
+Address for the "n" network interface card.  Typically, "n" corrosponds
+to eth0, eth1, and so on, but this isn't always the case.  You can
+specify these values to pertain to a different network controller with
+the INFAME[n] variable, but we will reserve that for the next chapter
+on wireless networking, as it more commonly pertains to wireless
+network controllers.  Likewise, NETMASK[n] is the subnet mask to use
+for the network controller.  If these lines are left empty, then static
+IP addresses will not be automatically assigned to this network
+controller.  The USE_DHCP[n] variable tells Slackware to (naturally)
+use DHCP to configure the interface.  DHCP_HOSTNAME[n] is rarely used,
+but some DHCP servers may require it.  In that case, it must be set to
+a valid hostname. Finally, we come to the GATEWAY variable.  It is
+actually set lower in the file than it appears in my example, and it
+controls the default gateway to use. You may be wondering why there is
+no GATEWAY[n] variable. The answer to that lies in how Internet
+Protocol works. I won't go into an indepth discussion on that subject,
+but suffice it to say that there is only ever one default route that a
+computer can use no matter how many interfaces are attached to it.
+</para>
+
+<para>
+If you need to use static IP addressing, you will have to obtain a
+unique static IP address and the subnet mask for the interface, as well
+as the default gateway address, and enter those here. There is no place
+to enter DNS information in <filename>rc.inet1.conf</filename>, so DNS
+servers will have to be manually placed into
+<filename>resolv.conf</filename> as we discussed above. Of course, if
+you use <application>netconfig</application>, this will be handled for
+you by that program.  Now let's take a look at another interface on my
+computer.
+</para>
+
+<screen>
+# Config information for eth1:
+IPADDR[1]=""
+NETMASK[1]=""
+USE_DHCP[1]="yes"
+DHCP_HOSTNAME[1]=""
+</screen>
+
+<para>
+Here I am telling Slackware to configure eth1 using DHCP. I do not need
+to set the IPADDR[1] or NETMASK[1] variables when using DHCP (in fact,
+if they are set, they will be ignored). Slackware will happily contact
+a DHCP server as soon as the machine begins to boot.
+</para>
+
+</section>
+
+</chapter>