Attachment 25851 Details for Bug 44143 – file.diff

[patch] file.diff

file.diff (text/plain), 13.96 KB, created by Eric Anderson on 2002-10-16 16:00:09 UTC

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Creator: Eric Anderson

Created: 2002-10-16 16:00:09 UTC

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>--- chapter.sgml	Tue Oct  8 02:41:18 2002
>+++ chapter.sgml-patch	Wed Oct 16 08:41:08 2002
>@@ -470,6 +470,299 @@
>     </sect2>
>   </sect1>
> 
>+  <sect1 id="wireless">
>+    <sect1info>
>+      <authorgroup>
>+        <author>
>+          <firstname>Eric</firstname>
>+          <surname>Anderson</surname>
>+          <contrib>Written by </contrib>
>+        </author>
>+      </authorgroup>
>+    </sect1info>
>+    <title>Wireless</title>
>+
>+   <sect2>
>+      <title>Introduction</title>
>+      <para>It can be very useful to be able to use a computer without the 
>+      annoyance of having a network cable attached at all times.  FreeBSD can
>+      be used as a wireless client, and even as a wireless <quote>access 
>+      point</quote>.</para>
>+   </sect2>
>+
>+   <sect2>
>+     <title>Wireless Devices</title>
>+     <para>There are two main types of wireless devices: access points, and clients.<para>
>+
>+     <sect3>
>+       <title>Access Points</title>
>+       <para>Access points are wireless networking devices that allow one or more wireless 
>+        clients to use the device as a central hub.  When using an access point, all 
>+        clients communicate through the access point.  Multiple access points are often 
>+        used to cover a complete area such as a house, business, or park with a wireless 
>+        network.</para>
>+
>+       <para>Access points typically have multiple network connections: the wireless card,
>+       and one or more wired ethernet adapters for connection to the rest of the network.
>+       </para>
>+
>+       <para>Access points can either be purchased prebuilt, or you can build 
>+        your own with FreeBSD and a supported wireless card.  Several vendors make 
>+        wireless access points and wireless cards with various features.</para>
>+     </sect3>
>+
>+     <sect3>
>+       <title>Building a FreeBSD Access Point</title>
>+       
>+       <sect4><title>Requirements</title>
>+         <para>In order to set up a wireless access point with FreeBSD, you need to have 
>+          a compatible wireless card.  Currently, only cards with the Prism chipset are 
>+          supported. You'll also need a wired network card that is also supported by FreeBSD 
>+          (this shouldn't be difficult to find, FreeBSD supports a lot of different 
>+          devices).  For this guide, we'll assume you want to &man.bridge.4; all traffic between 
>+          the wireless device and the network attached to the wired network card.</para>
>+       </sect4>
>+
>+       <sect4>
>+         <title>Setting it up</title>
>+         <para>First, make sure your system can see the wireless card:</para>
>+         <screen>&prompt.root; <userinput>ifconfig -a</userinput>
>+wi0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
>+        inet6 fe80::202:2dff:fe2d:c938%wi0 prefixlen 64 scopeid 0x7 
>+        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255
>+        ether 00:09:2d:2d:c9:50
>+        media: IEEE 802.11 Wireless Ethernet autoselect (DS/2Mbps)
>+        status: no carrier
>+        ssid ""
>+        stationname "FreeBSD Wireless node"
>+        channel 10 authmode OPEN powersavemode OFF powersavesleep 100
>+        wepmode OFF weptxkey 1</screen>
>+
>+         <para>Don't worry about the details now, just make sure it shows you 
>+          something to indicate you have a wireless card installed.</para>
>+
>+         <para>Next, you'll need to load a module in order to get the bridging part 
>+          of FreeBSD ready for the access point.  In order to load the &man.bridge.4; module, 
>+          simply run the following command:</para>
>+
>+         <screen>&prompt.root; <userinput>kldload bridge</userinput></screen>
>+
>+         <para>It should not have produced any errors when loading the module.  If it 
>+          did, you may need to compile the &man.bridge.4; code into your kernel.  The 
>+          (<xref linkend="bridging">) Handbook should be able 
>+          to help you accomplish that task.</para>
>+
>+         <para>Now that you have the bridging stuff done, we need to tell the FreeBSD 
>+          kernel which interfaces to bridge together.  We do that by using sysctl:</para>
>+
>+         <screen>&prompt.root; <userinput>sysctl net.link.ether.bridge=1</userinput></screen>
>+          <screen>&prompt.root; <userinput>sysctl net.link.ether.bridge_cfg="wi0 xl0"</userinput></screen>
>+          <screen>&prompt.root; <userinput>sysctl net.inet.ip.forwarding=1</userinput></screen>
>+
>+         <para>Now it's time for the wireless card setup.</para>
>+         <para>The following commands will set the card into BSS mode (turning it 
>+          into an access point):</para>
>+
>+         <screen>&prompt.root; <userinput>wicontrol -s "FreeBSD AP" -t 3 -n "my_net"</userinput></screen>
>+          <screen>&prompt.root; <userinput>ifconfig wi0 inet up ssid my_net mediaopt hostap</userinput></screen>
>+          <screen>&prompt.root; <userinput>wicontrol -p 6</userinput></screen>
>+
>+         <para>The first &man.wicontrol.8; command tells FreeBSD that the name of this access point 
>+          is FreeBSD AP by using the -s FreeBSD AP flags, to use auto rate selection at the 
>+          highest rate (11Mbps) with the -t 3 flags, and the SSID (station ID) is set to 
>+          my_net with the -n flag. Check out &man.wicontrol.8; for more information.</para>
>+
>+         <para>The &man.ifconfig.8; line brings the wi0 interface up, and sets its SSID to my_net.  
>+          This is a little redundant, but it's shown here to emphasize that you can do 
>+          these settings in either place.  You'll also notice a mediaopt hostap setting; 
>+          this setting is to tell &man.ifconfig.8; to put the interface into access point mode.</para>
>+
>+         <para>The second &man.wicontrol.8; line turns the interface into access point mode, instead 
>+          of the default IBSS (ad-hoc) mode.</para>
>+
>+         <para>Now you should have a complete functioning access point up and running.  You 
>+          are encouraged to read &man.wicontrol.8;, &man.ifconfig.8;, and &man.wi.4; for further information.
>+         </para>
>+
>+         <para>It is also suggested that you read the section on encryption that follows.</para>
>+       </sect4>
>+     </sect3>
>+
>+     <sect3>
>+       <title>Clients</title>
>+       <para>A wireless client is a system that accesses an access point or another client
>+       directly. </para>
>+
>+       <para>Typically, wireless clients only have one network device, the wireless 
>+       networking card.<para>
>+
>+       <para>There are a few different ways to configure a wireless client.  These are based 
>+        on the different wireless modes, generally BSS (infrastructure mode, which requires an 
>+        access point), and IBSS (ad-hoc, or peer-to-peer mode).  In our example, we'll use the 
>+        most popular of the two, BSS mode, to talk to an access point.</para>
>+
>+       <sect4>
>+       <title>Requirements</title>
>+       <para>There is only one real requirement for setting up FreeBSD as a wireless client.  
>+        You'll need a wireless card that is supported by FreeBSD.</para>
>+       </sect4>
>+
>+       <sect4>
>+       <title>Setting Up A Wireless FreeBSD Client</title>
>+       <para>You'll need to know a few things about the wireless network you are joining before 
>+        you start.  In this example, we are joining a network that has a name of my_net, and 
>+        encryption turned off.</para>
>+
>+       <para>Note:  In this example, we are not using encryption, which is a dangerous situation.  
>+        In the next section, you'll learn how to turn on encryption, and why it is important to 
>+         do so, and why some encryption technologies still don't completely protect you.</para>
>+
>+       <para>Make sure your card is recognized by FreeBSD:</para>
>+
>+       <screen>&prompt.root; <userinput>ifconfig -a</userinput>
>+wi0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
>+        inet6 fe80::202:2dff:fe2d:c938%wi0 prefixlen 64 scopeid 0x7 
>+        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255
>+        ether 00:09:2d:2d:c9:50
>+        media: IEEE 802.11 Wireless Ethernet autoselect (DS/2Mbps)
>+        status: no carrier
>+        ssid ""
>+        stationname "FreeBSD Wireless node"
>+        channel 10 authmode OPEN powersavemode OFF powersavesleep 100
>+        wepmode OFF weptxkey 1</screen>
>+
>+       <para>Now, we'll set the card to the correct settings for our network:</para>
>+
>+       <screen>&prompt.root; <userinput>ifconfig wi0 inet 192.168.0.20 netmask 255.255.255.0 ssid my_net</userinput></screen>
>+
>+       <para>Replace 192.168.0.20 and 255.255.255.0 with a valid IP address and netmask on 
>+        your wired network.  Remember, our access point is bridging the data between the 
>+        wireless network, and the wired network, so it will appear to the other devices on 
>+        your network that you are on the wired network just as they are.</para>
>+
>+       <para>Once you have done that, you should be able to ping hosts on the wired network 
>+        just as if you were connected using a standard wired connection.</para>
>+
>+       <para>If you are experiencing problems with your wireless connection, check to make 
>+        sure that your are associated (connected) to the access point:
>+     
>+       <screen>&prompt.root; <userinput>ifconfig wi0</userinput></screen>
>+
>+       should return some information, and you should see:</para>
>+       <screen>status: associated</screen>
>+
>+       <para>If it does not show associated, then you may be out of range of the access point, don't have 
>+       encryption on, or possibly have a configuration problem.</para>
>+
>+       </sect4>
>+     </sect3>
>+
>+     <sect3>
>+      <title>Encryption</title>
>+
>+      <para>Encryption on a wireless network is important because you no longer have the 
>+       ability to keep the network contained in a well protected area.  Your wireless data 
>+       will be broadcast across your entire neighborhood, so anyone who cares to read it 
>+       can.  This is where encryption comes in.  By encrypting the data that is sent over 
>+       the airwaves, you make it much more difficult for any interested party to grab your 
>+       data right out of the air. </para>
>+
>+     <para>The two most common ways to encrypt the data between your client and the access 
>+      point, are WEP, and &man.ipsec.4;.</para>
>+
>+     <sect4>
>+     <title>WEP</title>
>+      <para>WEP is an abbreviation for Wired Equivalency Protocol.  WEP is an attempt to 
>+       make wireless networks as safe and secure as a wired network.  Unfortunately, it 
>+       has been cracked, and is fairly trivial to break.  This also means it isn't something 
>+       to rely on when it comes to encrypting sensitive data.  </para>
>+
>+      <para>It's better than nothing, so here's how to turn on WEP on your new FreeBSD 
>+       access point:</para>
>+
>+      <screen>&prompt.root; <userinput>ifconfig wi0 inet up ssid my_net wepkey 0x1234567890 mediaopt hostap</userinput></screen>
>+
>+      <para>And here's how you turn on WEP on a client:</para>
>+
>+      <screen>&prompt.root; <userinput>ifconfig wi0 inet 192.168.0.20 netmask 255.255.255.0 ssid my_net wepkey 0x1234567890</userinput></screen>
>+
>+      <para>Note that you should replace the 0x1234567890 with a more unique key.</para>
>+
>+     </sect4>
>+    
>+     <sect4>
>+     <title>IPsec</title>
>+      <para>&man.ipsec.4; is a much more robust and powerful tool for encrypting data across a 
>+       network.  This is definitely the preferred way to encrypt wireless data over a 
>+       network.  You can read more about &man.ipsec.4; security and how to implement it in the 
>+       (<xref linkend="ipsec">) handbook.</para>
>+     </sect4>
>+    </sect3>
>+
>+    <sect3>
>+    <title>Tools</title>
>+    <para>There are a small number of tools available for use in debugging and setting 
>+    up your wireless network, and here we'll attempt to describe some of them and what 
>+    they do.</para>
>+
>+    <sect4>
>+    <title>bsd-airtools</title>
>+    <para>bsd-airtools is a package that includes wireless auditing tools for wep key 
>+    cracking, access point detection, etc.</para>
>+   
>+    <para>bsd-airtools can be installed from the ports collection.  Information on 
>+    installing ports can be found in (<xref linkend="ports">) the handbook.<para>
>+ 
>+    <para>dstumbler is the packaged tool that allows for access point discovery and 
>+    signal to noise ratio graphing.  If you are having a hard time getting your access 
>+    point up and running, dstumbler may help you get started.</para>
>+
>+    <para>To test your wireless network security, you may choose to use dweputils to 
>+    help you determine if wep is the right solution to your wireless security needs.</para>
>+
>+    </sect4>
>+
>+    <sect4>
>+    <title>wicontrol, ancontrol, raycontrol</title>
>+    <para>These are the tools you use to control how your wireless card behaves on the 
>+    wireless network.  In the examples above, we've chosen to use &man.wicontrol.8;, since our 
>+    wireless card is a wi0 interface.  If you had a Cisco wireless device, it would come 
>+    up as an0, and therefore you would use &man.ancontrol.8;.<para>
>+
>+    </sect4>
>+
>+    <sect4>
>+    <title>ifconfig</title>
>+    <para>&man.ifconfig.8; can be used to do many of the same options as &man.wicontrol.8;, however it 
>+    does lack a few options.  Check &man.ifconfig.8; for command line parameters and options.</para>
>+
>+    </sect4>
>+
>+    </sect3>
>+
>+    <sect3>
>+    <title>Supported Cards</title>
>+    <sect4>
>+    <title>Access Points</title>
>+    <para>The only cards that are currently supported for BSS (as an access point) mode are 
>+    devices based on the Prism (or Prism 2, 2.5) chipset. For a complete list, look 
>+    at &man.wi.4;.</para>
>+
>+    </sect4>
>+
>+    <sect4>
>+    <title>Clients</title>
>+    <para>Almost all 802.11b wireless cards are currently supported under FreeBSD.  Most 
>+     cards based on Prism, Spectrum24, Hermes, Aironet, and Raylink will work as a wireless
>+     network card in IBSS (ad-hoc, peer-to-peer, and BSS) mode.</para>
>+
>+    </sect4>
>+    </sect3>
>+
>+   </sect2>
>+  </sect1>
>+
>+
>   <sect1 id="bridging">
>     <sect1info>
>       <authorgroup>

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Attachments on bug 44143: 25851