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<!ENTITY ubuntu '<phrase>Ubuntu</phrase>'>
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<article id="troubleshooting" status="review">
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<title>Wireless networks</title>
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<sect1 id="network-troubleshooting" status="review">
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<title>Tools to help with network connection problems</title>
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<para>If you have a network connection which is not working properly, you can use a few tools to help diagnose what the problem is.</para>
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<para>Most of the tools in this section require use of the Terminal, which you can open by pressing &terminal;.</para>
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<sect2 id="network-troubleshooting-iwconfig" status="review">
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<title>Identify the wireless connections</title>
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<para><application>iwconfig</application> allows you to change certain settings on your wireless hardware. However, it is also very useful for identifying wireless connections.</para>
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<para>To identify a wireless connection:</para>
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<listitem><para>Press &terminal; to open a Terminal</para></listitem>
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<listitem><para>Type <userinput>iwconfig</userinput> in the Terminal and press <keycap>Enter</keycap></para></listitem>
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<para>You should get output similar to the following:</para>
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<screen>lo no wireless extensions.
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eth0 no wireless extensions.
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eth1 IEEE 802.11g ESSID:"WLAN Name"
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Mode:Managed Frequency:2.432 GHz Access Point: 00:12:CF:02:6F:EC
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Bit Rate:54 Mb/s Tx-Power=20 dBm Sensitivity=8/0
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Retry limit:7 RTS thr:off Fragment thr:off
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Link Quality=75/100 Signal level=-54 dBm Noise level=-89 dBm
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Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
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Tx excessive retries:0 Invalid misc:0 Missed beacon:1</screen>
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<listitem><para>The column on the left gives the name of the connection, such as <quote>eth0</quote> or <quote>wlan0</quote></para></listitem>
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<listitem><para>If the column on the right says <quote>no wireless extensions</quote>, that connection has not been recognized as a wireless connection and is probably a wired network connection</para></listitem>
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<listitem><para>If the connection <emphasis>has</emphasis> been recognized as a wireless connection, details of the wireless connection will be shown in the column on the right</para>
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<listitem><para><emphasis>ESSID</emphasis> gives the name of the wireless network that you are connected to, if any</para></listitem>
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<listitem><para><emphasis>Link Quality</emphasis> gives a measure of the strength of the wireless signal</para></listitem>
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<sect2 id="network-troubleshooting-iwlist" status="review">
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<title>Find information about the wireless connections</title>
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<para><application>iwlist</application> is able to display information about your wireless connection.</para>
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<listitem><para>Press &terminal; to open a Terminal</para></listitem>
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<para>Type the following commands in the Terminal and press <keycap>Enter</keycap> to run them. Make sure that you replace <emphasis>eth1</emphasis> with the name of your wireless interface, if it is different.</para>
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<listitem><para><userinput>iwlist eth1 accesspoints</userinput> - Show a list of available wireless access points</para></listitem>
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<listitem><para><userinput>iwlist eth1 rate</userinput> - Show a list of all possible transmission rates for your wireless connection, including the current rate</para></listitem>
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<listitem><para><userinput>iwlist eth1 key</userinput> - Show information about wireless encryption</para></listitem>
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<sect2 id="network-troubleshooting-ifconfig" status="review">
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<title>Get information about the current connection</title>
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<para><application>ifconfig</application> is intended to allow you to change the settings of your
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network connections, but it can also be used to list information about the current connection.</para>
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<listitem><para>Press &terminal; to open a Terminal</para></listitem>
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<para>Type <userinput>ifconfig eth1</userinput> in the Terminal and press <keycap>Enter</keycap>, replacing <emphasis>eth1</emphasis> with the name of your network interface if it is different.</para>
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<listitem><para><emphasis>inet addr</emphasis> gives the current <emphasis>IP address</emphasis> of the connection</para></listitem>
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<listitem><para><emphasis>HWaddr</emphasis> gives the <emphasis>MAC address</emphasis> of your network device</para></listitem>
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<sect2 id="network-troubleshooting-ping" status="review">
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<title>Check if a connection is working properly</title>
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<para>A good way of checking if a connection is working properly is to <emphasis>ping</emphasis> another computer on the network or the Internet.</para>
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<para>To check if you are connected to the Internet:</para>
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<listitem><para>Press &network-tools;</para></listitem>
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<listitem><para>Select the <guilabel>Ping</guilabel> tab</para></listitem>
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<listitem><para>Type <userinput>ubuntu.com</userinput> into the <guilabel>Network address</guilabel> box and then press <guibutton>Ping</guibutton></para></listitem>
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<para>After a while, a graph should appear. Look at the number for <guilabel>Successful packets</guilabel> under <guilabel>Transmission Statistics</guilabel></para>
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<listitem><para><emphasis>100% successful packets</emphasis> - Your computer should have a good connection to the Internet</para></listitem>
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<listitem><para><emphasis>Less than 100% successful</emphasis> - Your computer probably has a poor connection to the Internet or a poor wireless signal</para></listitem>
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<listitem><para><emphasis>0% successful packets</emphasis> - Your computer has a very bad connection, or is connected to an access point or router which is not connected to the Internet</para></listitem>
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<para>If you get an error message which says <emphasis>The address 'ubuntu.com' cannot be found</emphasis>, then your computer is probably not connected to the Internet or cannot reach a <emphasis>DNS server</emphasis>.</para>
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<chapter id="troubleshooting" status="review">
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<title>Troubleshooting</title>
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<para>Since the introduction of NetworkManager, connections can be enabled and disabled from the NetworkManager
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icon in the <guilabel>System Notification Area</guilabel>.</para>
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<para>Before attempting any troubleshooting, ensure that the connection is enabled:</para>
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<listitem><para>Right click the <guiicon>NetworkManager</guiicon> icon in the notification area.</para></listitem>
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<listitem><para>Check <guilabel>Enable Networking</guilabel>.</para></listitem>
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<listitem><para>Check <guilabel>Enable Wireless</guilabel>.</para></listitem>
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<sect1 id="troubleshooting-lan" status="review">
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<title>Wired troubleshooting</title>
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<para>If you have a network connection which is not working properly, you can use a few tools to help
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diagnose what the problem is.</para>
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<para>Most of the tools in this section require use of the Terminal, which you can open by pressing
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<sect2 id="network-troubleshooting-ifconfig" status="review">
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<title>Get information about the current connection</title>
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<para><application>ifconfig</application> is intended to allow you to change the settings of your
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network connections, but it can also be used to list information about the current connection.</para>
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<listitem><para>Press &terminal; to open a Terminal</para></listitem>
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<para>Type <userinput>ifconfig eth1</userinput> in the Terminal and press <keycap>Enter</keycap>, replacing <emphasis>eth1</emphasis> with the name of your network interface if it is different.</para>
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<listitem><para><emphasis>inet addr</emphasis> gives the current <emphasis>IP address</emphasis> of the connection</para></listitem>
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<listitem><para><emphasis>HWaddr</emphasis> gives the <emphasis>MAC address</emphasis> of your network device</para></listitem>
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<sect2 id="network-troubleshooting-ping" status="review">
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<title>Check if a connection is working properly</title>
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<para>A good way of checking if a connection is working properly is to <emphasis>ping</emphasis> another computer on the network or the Internet.</para>
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<para>To check if you are connected to the Internet:</para>
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<listitem><para>Press &network-tools;</para></listitem>
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<listitem><para>Select the <guilabel>Ping</guilabel> tab</para></listitem>
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<listitem><para>Type <userinput>ubuntu.com</userinput> into the <guilabel>Network address</guilabel> box and then press <guibutton>Ping</guibutton></para></listitem>
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<para>After a while, a graph should appear. Look at the number for <guilabel>Successful packets</guilabel> under <guilabel>Transmission Statistics</guilabel></para>
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<listitem><para><emphasis>100% successful packets</emphasis> - Your computer should have a good connection to the Internet</para></listitem>
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<listitem><para><emphasis>Less than 100% successful</emphasis> - Your computer probably has a poor connection to the Internet or a poor wireless signal</para></listitem>
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<listitem><para><emphasis>0% successful packets</emphasis> - Your computer has a very bad connection, or is connected to an access point or router which is not connected to the Internet</para></listitem>
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<para>If you get an error message which says <emphasis>The address 'ubuntu.com' cannot be found</emphasis>, then your computer is probably not connected to the Internet or cannot reach a <emphasis>DNS server</emphasis>.</para>
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<sect1 id="troubleshooting-wireless" status="review">
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<title>Wireless troubleshooting</title>
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<para>While not exhaustive, this section covers some common problems faced with wireless support.</para>
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<para>There is much more information available from the <ulink url="https://help.ubuntu.com/community/WifiDocs">Community Documentation</ulink>.</para>
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<note><para>This troubleshooting guide is designed to be carried out in order. If you reach the end of a section
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and are not directed to another - then try <xref linkend="connecting-wireless"/> and should it fail begin at the start again.</para></note>
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<sect2 id="troubleshooting-wireless-disabled" status="review">
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<title>Check that the device is on</title>
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<listitem><para>Many wireless network devices can be turned on or off. Check to see if there is a hardware switch, some devices can be switched off from Windows and may need to be turned back on from Windows.</para></listitem>
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<listitem><para>If it is turned on then see <xref linkend="troubleshooting-wireless-device"/>.</para></listitem>
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<sect2 id="troubleshooting-wireless-device" status="review">
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<title>Check for device recognition</title>
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<listitem><para>Open a <application>Terminal</application> (&terminal;) and type the command: <code>sudo lshw -C network</code></para></listitem>
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<para>You should see an output, along with the words "CLAIMED, UNCLAIMED, ENABLED or DISABLED"</para>
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<listitem><para>Claimed - this indicates a driver is loaded but not functioning, see <xref linkend="troubleshooting-wireless-ndiswrapper"/></para></listitem>
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<listitem><para>Unclaimed - there is no driver loaded, see <xref linkend="troubleshooting-wireless-ndiswrapper"/>.</para></listitem>
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<listitem><para>Enabled - move on to If there is a driver listed then see <xref linkend="troubleshooting-wireless-connection" />.</para></listitem>
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<listitem><para>Disabled - see <xref linkend="troubleshooting-wireless-disabled"/>.</para></listitem>
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<sect2 id="troubleshooting-wireless-ndiswrapper" status="review">
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<title>Using Windows Wireless Drivers</title>
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<para>Ubuntu supports a system known as NDISWrapper. This allows you to use a Windows wireless device driver under Ubuntu.</para>
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<listitem><para>Obtain the Windows Driver for your system and locate the file that ends with <code>.inf</code>.</para></listitem>
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<listitem><para><ulink url="apt:ndisgtk">Install the <application>ndisgtk</application> package</ulink>.</para></listitem>
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<listitem><para>Open <application>ndisgtk</application> (&ndisgtk;).</para></listitem>
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<listitem><para>Select <guilabel>Install new driver</guilabel>.</para></listitem>
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<listitem><para>Choose the location of your Windows .inf file and click <guibutton>Install</guibutton>.</para></listitem>
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<listitem><para>Click <guibutton>OK</guibutton>.</para></listitem>
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<sect2 id="troubleshooting-wireless-connection" status="review">
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<title>Check for a connection to the router</title>
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<listitem><para>Open a <application>Terminal</application> (&terminal;) and type the command: <code>iwconfig</code>.</para></listitem>
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<listitem><para>If the ESSID for our router is shown there may be a problem with ACPI support. Boot the kernel with the <code>pci=noacpi</code> option.</para></listitem>
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<sect2 id="troubleshooting-wireless-ip" status="review">
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<title>Check IP assignment</title>
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<listitem><para>Open a <application>Terminal</application> (&terminal;) and type the command: <code>ifconfig</code>.</para></listitem>
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<listitem><para>If there is an IP address shown see <xref linkend="troubleshooting-wireless-dns"/>.</para></listitem>
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<listitem><para>From the <application>Terminal</application> enter the command: <code>sudo dhclient if_name</code> where if_name is the connection listed earlier.</para></listitem>
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<listitem><para>If you receive a message that says <code>bound to xxx.xxx.xxx.xxx</code> then see <xref linkend="troubleshooting-wireless-dns"/></para></listitem>
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<listitem><para>If not then reboot the system.</para></listitem>
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<sect2 id="troubleshooting-wireless-dns" status="review">
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<title>Check DNS</title>
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<listitem><para>Open a <application>Terminal</application> (&terminal;) and type the command: <code>ping -c3 85.190.27.2</code>.</para></listitem>
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<listitem><para>Now type the command: <code>ping www.ubuntu.com</code>. If you get a response from the both then see <xref linkend="troubleshooting-wireless-ipv6"/>.</para></listitem>
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<listitem><para>Type the command: <code>cat /etc/resolv.conf</code>. If there is no nameserver listed then contact your ISP and find out your primary and secondary domain name servers. Once you have this information see <xref linkend="connecting-wireless"/>.</para></listitem>
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<sect2 id="troubleshooting-wireless-ipv6" status="review">
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<title>IPv6 Not Supported</title>
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<listitem><para>IPv6 is supported by default in Ubuntu and can sometimes cause problems.</para></listitem>
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<listitem><para>To disable it, open a <application>Terminal</application> (&terminal;) and type the command: <code>gksudo gedit /etc/modprobe.d/aliases</code>.</para></listitem>
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<listitem><para>Find the line <code>alias net-pf-10 ipv6</code> and change it to read <code>alias net-pf-10 off</code>.</para></listitem>
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<listitem><para>Reboot Ubuntu.</para></listitem>
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internet/C/troubleshooting.xml
