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	<title>Cacti Frequently Asked Questions</title>
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<h1>Cacti Frequently Asked Questions (FAQ)</h1><p>

<h2>Using Cacti</h2><p>

<ol>
	<li>
		<strong>How do I create traffic graphs?</strong>
		
		<p>Before you can create traffic graphs, Cacti must have working SNMP support. One way to do this is to
		compile PHP with SNMP support built in, many times you can install the 'php-snmp' package to do this. The
		second option is to have Cacti call the snmpget and snmpwalk binaries from your ucd-snmp or net-snmp
		installation. You can use the about page to determine whether to are using "built-in" or "external" SNMP
		support.</p>
		
		<p>Now that you have working SNMP support, follow these steps.</p>
		
		<ol>
			<li>Click "Polling Hosts" on Cacti's menu.</li>
			<li>Click "Add" to add a new polling host.</li>
			<li>Type a description, hostname, management IP, and SNMP community. Make sure to select "Generic SNMP-enabled Host"
			under "Host Template" and click "Create".</li>
			<li>You should see one or more interfaces listed under the "Data Query [SNMP - Interface Statistics]" box. Place a
			check next to each interface that you want to graph. Below the box, select type of graph that you want to create
			(bits, bytes, summation, etc).</li>
			<li>Click "Save", and "Create" on the following screen to create your graphs.</li>
		</ol>
	</li>
</ol>

<h2>General</h2><p>
	
<ol>
	<li>
		<strong>I get the following error message from Cacti: <em>Warning: Undefined variable: _SERVER in 
		.../cacti/install/index.php on line 59</em></strong>
		
		<p>Cacti 0.8 and above requires that you have at least PHP 4.1 or greater installed.</p>
	</li>
	<li>
		<strong>I get the following error message from Cacti: <em>Fatal error: Call to undefined function: 
		mysql_connect() in /usr/share/cacti/include/database.php on line 19</em></strong>
		
		<p>Your installation of PHP does not have MySQL installed or enabled. On binary-based distributions, make sure
		you have the 'php-mysql' package installed. Also make sure that 'extension=mysql.so' is uncommented in your
		php.ini file.</p>
	</li>
	<li>
		<strong>I have forgotten my 'admin' password to Cacti, how do I reset it?</strong>
		
		<p>To reset the admin account password back to the default of 'admin', connect to your Cacti database at the command line.</p>
		
		<p class="code"><tt class="shell">shell&gt;</tt> <b>mysql -u root -p cacti</b></p>
		
		<p>Now execute the following SQL:</p>
		
		<p class="code"><tt class="shell">mysql&gt;</tt> <b>update user_auth set password='21232f297a57a5a743894a0e4a801fc3' where username='admin';</b></p>
	</li>
</ol>


<h2>Monitoring</h2><p>

<ol>
	<li>
		<strong>I am polling thousands of items and cmd.php takes more than 5 minutes to run.</strong>
		
		<p>Give cactid, the future replacement for cmd.php a try. Unlike cmd.php, cactid is written in c and makes use
		of pthreads. On a typical installation, it is not uncommon for cactid to poll about 500 items in less then 10
		seconds.</p>
	</li>
	<li>
		<strong>I changed <em>x</em>, and now some of my graphs are not updating.</strong>
		
		<p>The best thing to do here is to force Cacti to rebuild its poller cache. To do this click "Utilities"
		on the Cacti menu, and simply select "Clear Poller Cache".</p>
	</li>
	<li>
		<strong>I am using Redhat 8.0 and SNMP is not working.</strong>
		
		<p>Redhat 8.0 comes with a broken php-snmp package. Updating your 'php-snmp' and 'net-snmp' packages to their latest
		versions should fix this problem.</p>
	</li>
	<li>
		<strong>How do I configure net-snmp so it will work with Cacti?</strong>
		
		<p>Run <em>snmpconf -g basic_setup</em> and follow the prompts. Also check that the file being used by snmpd is the correct 
		config file. For Redhat Linux, snmpconf creates the /etc/snmpd.conf, but snmpd uses /etc/snmpd/snmpd.conf.</p>
		
		<p>If this doesn't work a very simple config file is:</p>
		
		<p class="code"># contact<br>
		syslocation  Something<br>
		syscontact  "root@someone.com"<br>
		<br>
		# auth<br>
		rocommunity  public<br>
		<br>
		# disk monitoring<br>
		disk /</p>
	</li>
</ol>

<h2>Graphs</h2><p>

<ol>
	<li>
		<strong>I just installed Cacti and all of my graphs appear as broken images.</strong>
		
		<p>For you to actually get graph images, cmd.php must run at least once so it can create .rrd files in Cacti's
		'rra/' directory. Double check that you configured your /etc/crontab file to execute cmd.php every five minutes.
		Also make sure that the user cmd.php runs as has permission to create new files in Cacti's 'rra/' directory.</p>
		
		<p>If all of your settings appear correct, try running cmd.php manually by cd'ing to Cacti's directory and typing:</p>
		
		<p class="code"><tt class="shell">shell&gt;</tt> <b>php cmd.php</b></p>
		
		<p>If you have files in your 'rra/' directory, but your graphs still appear as broken images, you should enable
		graph debug mode see exactly why the graphs are not rendering. To do this go into Cacti, select "Graph Management"
		from the menu, select any graph listed, and select "Turn On Graph Debug Mode".</p>
	</li>
	<li>
		<strong>My graphs render, but they do not contain any data.</strong>
		
		<p>More often than not, this problem's cause is permissions. For instance if you run cmd.php manually as root for
		testing, any .rrd files that it creates will be owned by root. Now when cmd.php runs from cron, it will not be
		able to update these .rrd files because they are owned by root. You can double check the owner of your .rrd files
		by running the following command in your Cacti directory:</p>
		
		<p class="code"><tt class="shell">shell&gt;</tt> <b>ls -al rra/</b></p>
		
		<p>If only some of your graphs are not updating correctly, double check the "Maximum Value" field for all data
		sources used by these graphs. If the value being fed to the .rrd file exceeds its "Maximum Value", RRDTool will insert
		an "Unknown" and you will see no data on the graph.</p>
	</li>
	<li>
		<strong>A lot of my graphs contain long ifAlias names, but they are being truncated to 15 characters.</strong>
		
		<p>Cacti does this by default to better control graph title formatting. You can change this limit, by going to "Cacti
		Settings" on the Cacti menu, selecting the "Visual" tab, and changing the value for "Data Queries - Maximum Field Length".</p>
	</li>
	<li>
		<strong>One of my devices rebooted and now I have a huge spike on my graph!</strong>
		
		<p>This occurs because the reboot causes SNMP's counters to reset, which can cause a rather large spike on the graph
		when RRDTool tries to determine the change between the new small counter value and the large previous value. One way to
		combat this issue is to specify realistic maximum values for your data sources. RRDTool will ignore any value that is larger
		than the maximum value.</p>
		
		<p>If you already have a spike on one or more of your graphs, there is a really 
		<a href="http://cricket.sourceforge.net/contrib/files/killspike2">useful Perl script</a> that will remove them for you.</p>
	</li>
</ol>

<h2>Windows Related</h2><p>

<ol>
	<li>
		<strong>I get the following error message from Cacti: <em>Fatal error: Cannot redeclare title_trim() (previously 
		declared in ...\cacti\include\functions.php:27)</em></strong>
		
		<p>Contrary to previous versions of Cacti, you must not put Cacti in your PHP include path. Check your php.ini file to make
		sure there is not something like '<em>include_path = C:/Apache2/htdocs/cacti</em>'.
	</li>
</ol>