path: root/chapter_15.xml

<?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>Wireless Networking</title>

<section>
<title><application>iwconfig</application></title>

<para>
Wireless networking is somewhat more complicated than traditional wired
networking, and requires additional tools for setup. Slackware includes
a diverse collection of wireless networking tools to allow you to
configure your wireless network interface card (WNIC) at the most basic
level. We won't cover everything here, but should give you a solid
foundation to get up and running quickly.  The first tool we are going
to look at is <application>iwconfig</application>(8). When run without
any argument, <application>iwconfig</application> displays the current
wireless information on any and all NICs on your computer.
</para>


<screen><prompt>darkstar:~# </prompt><userinput>iwconfig</userinput>
lo        no wireless extensions.

eth0      no wireless extensions.

wmaster0  no wireless extensions.

wlan0     IEEE 802.11abgn  ESSID:"nest"  
          Mode:Managed  Frequency:2.432 GHz  Access Point:
00:13:10:EA:4E:BD   
          Bit Rate=54 Mb/s   Tx-Power=17 dBm   
          Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
          Encryption key:off
          Power Management:off
          Link Quality=100/100  Signal level:-42 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

tun0      no wireless extensions.
</screen>

<para>
Unlike wired networks, wireless networks are "fuzzy". Their borders are
hard to define, and multiple networks may overlap one another. In order
to avoid confusion, each wireless network has (hopefully) unique
identifiers. The two most basic identifiers are the Extended Service
Set Identifier (ESSID) and the channel or frequency for radio
transmission. The ESSID is simply a name that identifies the wireless
network in question; you may have heard it referred to as the network
name or something similar. Typical wireless networks operate on 11
different frequencies. In order to connect to even the most basic
wireless network, you will have to setup these two pieces of
information, and possibly others, before setting up things like the
WNIC's IP address. Here you can see that my ESSID is set to "nest" and
my laptop is transmitting at 2.432 GHz. This is all that is required to
connect to an unencrypted wireless LAN. (For any of you out there
expecting to come to my house and use my unencrypted wireless, you
should know that you'll have to break a 2048-bit SSL key before the
access point will let you communicate with my LAN.)
</para>

<screen><prompt>darkstar:~# </prompt><userinput>iwconfig wlan0 essid nest \
  freq 2.432G</userinput></screen>

<para>
The <arg>freq</arg> and <arg>channel</arg> arguments control basically
the same thing.  You only need to use one.  If you are unsure what
frequency or channel to use, Slackware can usually figure this out for
you.
</para>

<screen><prompt>darkstar:~# </prompt><userinput>iwconfig wlan0 essid nest \
  channel auto</userinput></screen>

<para>
Now Slackware will attempt to connect to the strongest access point on
the "nest" essid operating at any frequency.
</para>

</section>

<section>
<title>Wired Equivilant Protection (or Lack Thereof)</title>

<para>
Wireless networking is by its very nature less secure than wired
networking. Having your information travelling on the airwaves makes it
highly susceptible to interception by third paries, so over the years a
number of methods have been devised to make wireless networking more
secure.  The first was called Wired Equivilant Protection, or WEP for
short, and well far short of its goal. If you are still using WEP
today, I encourage you to consider using WPA2 or some other form of
stronger encryption. Attacks against WEP are trivial and take only
minutes to perform. Unfortunately there are still access points
configured for WEP, and you may need to connect to one from time to
time. Connecting to WEP encrypted access points is fairly simple,
particularly if you have the key in hexidecimal format. We'll need to
pass the <arg>key</arg> argument along with the password in hexidecimal
or ASCII format. If using an ASCII password, you'll need to prepend it
with "s:"; here's a couple examples.  Generally speaking, hexidecimal
format is prefered.
</para>

<screen><prompt>darkstar:~# </prompt><userinput>iwconfig wlan0 \
  key cf80baf8bf01a160de540bfb1c</userinput>
<prompt>darkstar:~# </prompt><userinput>iwconfig wlan0 \
  key s:thisisapassword</userinput>
</screen>

</section>

<section>
<title>Wifi Protected Access</title>

<para>
Wifi Protected Access (or WPA for short) was the successor for WEP that
aimed to fix several problems with wireless encryption. Unfortunately,
WPA had some flaws as well.  An update called WPA2 offers even stronger
protection. At this time, WPA2 is supported by nearly all wireless
network cards and access points, but some older devices may only
support WEP. If you need to secure your wireless network traffic, WPA2
should be considered the minimum level of protection required.
Unfortunately, <application>iwconfig</application> is unable to setup
WPA2 encryption on its own.  For that, we need a helper daemon,
<application>wpa_supplicant</application>(8).
</para>

<para>
Unfortunately, there's no easy way to manually configure a WPA2
protected network; you'll have to edit
<filename>/etc/wpa_supplicant.conf</filename> directly with a text
editor. Here we will discuss the simplest form of WPA2 protection, the
Pre-Shared Key, or PSK for short. For details on setting up Slackware
to connect to more complicated WPA2 encrypted networks, see the man
page for <filename>wpa_supplicant.conf</filename>.
</para>

<screen>
# /etc/wpa_supplicant.conf
# ========================
# This line enables the use of wpa_cli which is used by rc.wireless
# if possible (to check for successful association)
ctrl_interface=/var/run/wpa_supplicant
# By default, only root (group 0) may use wpa_cli
ctrl_interface_group=0
eapol_version=1
ap_scan=1
fast_reauth=1
#country=US

# WPA protected network, supply your own ESSID and WPAPSK here:
network={
  scan_ssid=1
  ssid="nest"
  key_mgmt=WPA-PSK
  psk="secret passphrase"
}
</screen>

<para>
The block of text we're interested in is the network block enclosed by
curly braces.  Here we have set the ssid for the network "nest", as well
as the PSK to use "secret passphrase". At this point, WPA2 is setup.
You can run <application>wpa_supplicant</application> and then obtain
an IP address via DHCP or set a static address.  Of course, this is a
lot of work, there must be an easier way to do this.
</para>

</section>

<section>
<title>rc.inet1.conf revisited</title>

<para>
Welcome back to <filename>rc.inet1.conf</filename>.  You're recall in
the last chapter that we used this configuration file to automatically
configure NICs whenever Slackware boots.  Now, we will use it to
configure wifi as well.  If you're using WPA2, you'll still need to
setup <filename>wpa_supplicant.conf</filename> properly first, however.
</para>

<para>
Recall that each NIC had a name or number that identified the variables
that corrospond with it?  The same hold true for wifi NICs, only they
have even more variables due to the added complexity of wireless
networking.
</para>

<screen>
# rc.inet1.conf (excert)
# ======================
## Example config information for wlan0.  Uncomment the lines you need and fill
## in your info.  (You may not need all of these for your wireless network)
IFNAME[4]="wlan0"
IPADDR[4]=""
NETMASK[4]=""
USE_DHCP[4]="yes"
#DHCP_HOSTNAME[4]="icculus-wireless"
#DHCP_KEEPRESOLV[4]="yes"
#DHCP_KEEPNTP[4]="yes"
#DHCP_KEEPGW[4]="yes"
#DHCP_IPADDR[4]=""
WLAN_ESSID[4]="nest"
#WLAN_MODE[4]=Managed
#WLAN_RATE[4]="54M auto"
#WLAN_CHANNEL[4]="auto"
#WLAN_KEY[4]="D5AD1F04ACF048EC2D0B1C80C7"
#WLAN_IWPRIV[4]="set AuthMode=WPAPSK | \
#   set EncrypType=TKIP | \
#   set WPAPSK=96389dc66eaf7e6efd5b5523ae43c7925ff4df2f8b7099495192d44a774fda16"
WLAN_WPA[4]="wpa_supplicant"
#WLAN_WPADRIVER[4]="ndiswrapper"
</screen>

<para>
When we discussed wired ethernet, each "n" in the variable corrosponded
with the "n" in ethn.  Here however, that no longer holds true. Notice
that the variable IFNAME[4] has a value of "wlan0". It is common for
wireless cards to have an interface name other than "ethn" and that is
reflected here.  When <filename>rc.inet1.conf</filename> is read by the
start-up scripts, Slackware knows to apply all these options to the
"wlan0" wifi NIC instead of the (probably non-existant) eth4 wired NIC.
Many of the other options are the same.  IP address information is
added in exactly the same way we discussed for wired network cards in
the previous chapter; however, we have a lot of new variables that need
some explaination.
</para>

<para>
To begin, WLAN_ESSID[n] and WLAN_CHANNEL[n] should be self-explainatory
by now; they refer the the essid and frequency to use.  WLAN_MODE[n] is
either "managed" or "ad-hoc".  Anyone connecting to an access point
will want to use managed mode.  WLAN_KEY[n] is the WEP key to use, if
you're forced to use WEP.  WLAN_IWPRIV[n] is a very complicated
variable that sets other variables inside itself.  WLAN_IWPRIV[n] is
used for WPA2 networks.  Here you tell Slackware what authentication
mode, encryption type, and key to use for WPA2 connections.  Please
note that WLAN_KEY[n] and WLAN_IWPRIV[n] are mutually exclusive; you
can't use both on the same interface.  If you successfully configure
all this, then Slackware will attempt to connect to your wireless
network as soon as the system boots.
</para>

<para>
But wait, that's so much work!  And what if I need to connect to
multiple wireless networks?  I take my laptop to work and school and
need to seemlessly setup those wireless connections as soon as one is
within range.  Doing things this way is simply too much work.  You're
absolutely correct.
</para>

</section>

<section>
<title>wicd</title>

<para>
Introducing <application>wicd</application>(8), the premier wired and
wireless network connection manager for the laptop user on the go.
Pronounced "wicked", <application>wicd</application> is capable of
storing information for any number of wireless networks you need and
connecting to them with a simple command or the click of a mouse.
<application>wicd</application> is not part of the default Slackware
installation at this time, as it interferes somewhat with the normal
way of configuring network adapters, but you can find it in the
<filename>/extra</filename> directory of your Slackware install disks
or at your favorite mirror. <application>wicd</application> is both a
network connection daemon and a graphical application for configuring
networks.  The CLI isn't forgotten either, as
<application>wicd-curses</application>(8) is every bit as powerful as
the traditional GUI front-end.  In order to use
<application>wicd</application>, you will need to disable support for
any interfaces you have in <filename>rc.inet1.conf</filename> first.
</para>

<screen>
# rc.inet1.conf
# =============
# Config information for eth0:
IPADDR[0]=""
NETMASK[0]=""
USE_DHCP[0]="no"
DHCP_HOSTNAME[0]=""
# Default gateway IP address:
GATEWAY=""
</screen>

<para>
Now we can install <application>wicd</application>, setup the daemon to
run on system boot-up, and begin using a more friendly application.
</para>

<screen><prompt>darkstar:~# </prompt><userinput>installpkg /path/to/extra/wicd/wicd-1.6.2.1-1.txz</userinput>
<prompt>darkstar:~# </prompt><userinput>chmod +x /etc/rc.d/rc.wicd</userinput>
<prompt>darkstar:~# </prompt><userinput>/etc/rc.d/rc.wicd start</userinput>
</screen>

<para>
If you're predominately using the console, simply run
<application>wicd-curses</application> from your command line. If
instead, you are using a graphical desktop provided by
<application>X</application>, you can start the graphical front-end
from either the KDE or XFCE menu.  Optionally, you could manually run
<application>wicd-client</application>(1) from a terminal or run
dialogue.
</para>

<para>
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
ADD PICTURES OF WICD-CURSES AND WICD-CLIENT!!!!
</para>

</section>

</chapter>