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<chapter>
    <chapterinfo>
	<revhistory>
	    <revision>
		<revnumber>$Revision: 1827 $</revnumber>
		<date>$Date: 2007-03-12 17:22:53 +0200 (Mon, 12 Mar 2007) $</date>
	    </revision>
	</revhistory>
    </chapterinfo>
    <title>Frequently Asked Questions</title>
    <qandaset defaultlabel="number">
	<qandaentry>
	    <question>
		<para>Where can I find more about SNMP?</para>
	    </question>
	    <answer>
		<para>
			There are many websites that explain SNMP at all levels of detail.
			A great general introduction can be found at http://en.wikipedia.org/wiki/SNMP

			If you are interested in the nitty gritty details of the protocol, 
			then please look at RFC 3410.  RFC 3410 maps out the many other RFCs
			that define SNMP, and can be found at http://www.rfc-archive.org/getrfc.php?rfc=3410
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Where can I find more about NetSNMP?</para>
	    </question>
	    <answer>
		<para>
			NetSNMP source code, documentation, FAQs, and tutorials can all be found at
			http://net-snmp.sourceforge.net/.
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Where can I find out more about AgentX?</para>
	    </question>
	    <answer>
		<para>
			The full details of the AgentX protocol are explained in RFC 2741, 
			available at: http://www.rfc-archive.org/getrfc.php?rfc=2741
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Why am I not receiving any SNMP Traps?</para>
	    </question>
	    <answer>
		<para>
		Assuming you've configured the trap thresholds in openser.cfg with something similar to:
		</para>

		<programlisting format="linespecific">
    modparam("snmpstats", "MsgQueueMinorThreshold", 1234)
    modparam("snmpstats", "MsgQueueMajorThreshold", 5678)

    modparam("snmpstats", "dlg_minor_threshold", 500)
    modparam("snmpstats", "dlg_minor_threshold", 600)
		</programlisting>
		<para>
		Then either OpenSER is not reaching these thresholds (which is a good thing),
		or you haven't set up the trap monitor correctly.  To prove this to yourself,
		you can start NetSNMP with:
		</para>

		<programlisting format="linespecific">
    snmpd -f -Dtrap -x localhost:705
		</programlisting>

		<para>
		The -f tells the NetSNMP process to not daemonize, and the -Dtrap enables trap
		debug logs.  You should see something similar to the following: 
		</para>

		<programlisting format="linespecific">
    registered debug token trap, 1
    trap: adding callback trap sink            ----- You should see both
    trapsess: adding to trap table             ----- of these lines.
    Turning on AgentX master support.
    trap: send_trap 0 0 NET-SNMP-TC::linux
    trap: sending trap type=167, version=1
    NET-SNMP version 5.3.1
		</programlisting>

		<para>
		If the two lines above did not appear, then you probably have not included
		the following in your snmpd.conf file.
		</para>
		
		<programlisting format="linespecific">
    trap2sink machineToSendTrapsTo:machinesPortNumber.
		</programlisting>

		<para>
		When a trap has been received by snmpd, the following will appear in the
		above output:
		</para>

		<programlisting format="linespecific">
    sent_trap -1 -1 NET-SNMP-TC::linus
    sending trap type=167, version=1
		</programlisting>

		<para>
		You'll also need a program to collect the traps and do something with them
		(such as sending them to syslog).  NetSNMP provides snmptrapd for this.  Other
		solutions exist as well.  Google is your friend.
		</para>		
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>OpenSER refuses to load the SNMPStats module.  Why is it displaying "load_module: could not open module snmpstats.so"?
		</para>
	    </question>
	    <answer>
		<para>
		On some systems, you may receive the following error at stdout or the log files
		depending on the configuration.  
		</para>

		<programlisting format="linespecific">
    ERROR: load_module: could not open module &lt;/usr/local/lib/openser/modules/snmpstats.so&gt;: 
           libnetsnmpmibs.so.10: cannot open shared object file: No such file or directory.
		</programlisting>
	
		<para>	
		This means one of two things:
		</para>
	
		<orderedlist numeration="arabic">
			<listitem>
				<para>
				You did not install NetSNMP.  ("make install" if building from source)
				</para>
			</listitem>
			<listitem>
				<para>
				The dynamic linker cannot find the necessary libraries.  
				</para>
			</listitem>
		</orderedlist>
		
		<para>	
		In the second case, the fix is as follows:
		</para>

		<orderedlist numeration="arabic">
			<listitem>
				<para>
				find / -name "libnetsnmpmibs*"
				<itemizedlist>
					<listitem>
						<para>
			You will find a copy unless you haven't installed NetSNMP.
			Make note of the path.
						<para>
					</listitem>
				</itemizedlist>
				</para>
			</listitem>
			<listitem>
				<para>
				less /etc/ld.so.conf
				<itemizedlist>
					<listitem>
						<para>
			If the file is missing the path from step 1, then add the path to
			ld.so.conf
						<para>
					</listitem>
				</itemizedlist>

				</para>
			</listitem>
			<listitem>
				<para>
				ldconfig
				</para>
			</listitem>
			<listitem>
				<para>
				Try starting OpenSER again.
				</para>
			</listitem>
		</orderedlist>

		<para>
		Alternatively, you may prefix your startup command with:
		</para>

		<programlisting format="linespecific">
    LD_LIBRARY_PATH=/path/noted/in/step/one/above
		</programlisting>

	    	<para>
		For example, on my system I ran:
		</para>

		<programlisting format="linespecific">
    LD_LIBRARY_PATH=/usr/local/lib openserctl start
		</programlisting>

	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>How can I learn what all the scalars and tables are?</para>
	    </question>
	    <answer>
		<para>
		All scalars and tables are named in the SNMPStats module overview.  The files
		OPENSER-MIB, OPENSER-REG-MIB, OPENSER-SIP-COMMON-MIB and OPENSER-SIP-SERVER-MIB
		contain the full definitions and descriptions.  Note however, that the MIBs
		may actually contain scalars and tables which are currently not provided by the
		SNMPStats module.  Therefore, it is better to use NetSNMP's snmptranslate
		as an alternative. Take the openserSIPEntityType scalar as an example. You can
		invoke snmptranslate as follows:

		<programlisting format="linespecific">
    snmptranslate -TBd openserSIPEntityType
		</programlisting>		

		Which would result in something similar to the following:

		<programlisting format="linespecific">
    -- FROM       OPENSER-SIP-COMMON-MIB
    -- TEXTUAL CONVENTION OpenSERSIPEntityRole
    SYNTAX        BITS {other(0), userAgent(1), proxyServer(2), redirectServer(3), registrarServer(4)} 
    MAX-ACCESS    read-only
    STATUS        current
    DESCRIPTION   " This object identifies the list of SIP entities this
                   row is related to. It is defined as a bit map.  Each
                   bit represents a type of SIP entity.
                   If a bit has value 1, the SIP entity represented by
                   this row plays the role of this entity type.
  
                   If a bit has value 0, the SIP entity represented by
                   this row does not act as this entity type
                   Combinations of bits can be set when the SIP entity
                   plays multiple SIP roles."
		</programlisting>  

		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Why do snmpget, snmpwalk, and snmptable always time out?</para>
	    </question>
	    <answer>
		<para>
		If your snmp operations are always returning with: "Timeout: No Response
		from localhost", then chances are that you are making the query with the wrong
		community string.  Default installs will most likely use "public" as their
		default community strings. Grep your snmpd.conf file for the string 
		"rocommunity", and use the result as your community string in your queries.
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>How do I use snmpget?</para>
	    </question>
	    <answer>
		<para>
		NetSNMP's snmpget is used as follows:

		<programlisting format="linespecific">
    snmpget -v 2c -c theCommunityString machineToSendTheMachineTo scalarElement.0
    		</programlisting>

		For example, consider an snmpget on the openserSIPEntityType scalar, 
		run on the same machine running the OpenSER instance, with the default
		"public" community string.  The command would be:

		<programlisting format="linespecific">
    snmpget -v2c -c public localhost openserSIPEntityType.0
		</programlisting>

		Which would result in something similar to:

		<programlisting format="linespecific">
    OPENSER-SIP-COMMON-MIB::openserSIPEntityType.0 = BITS: F8 \
		other(0) userAgent(1) proxyServer(2)          \
		redirectServer(3) registrarServer(4) 
		</programlisting>

		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>How do I use snmptable?</para>
	    </question>
	    <answer>
		<para>
		NetSNMP's snmptable is used as follows:

		<programlisting format="linespecific">
    snmptable -Ci -v 2c -c theCommunityString machineToSendTheMachineTo theTableName
    		</programlisting>

		For example, consider the openserSIPRegUserTable.  If we run the snmptable
		command on the same machine as the running OpenSER instance, configured with
		the default "public" community string.  The command would be:

		<programlisting format="linespecific">
    snmptable -Ci -v 2c -c public localhost openserSIPRegUserTable
		</programlisting>

		Which would result in something similar to:

		<programlisting format="linespecific">
    index openserSIPUserUri openserSIPUserAuthenticationFailures
        1       DefaultUser                                    0
        2            bogdan                                    0
        3    jeffrey.magder                                    0
		</programlisting>

		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Where can I find more about OpenSER?</para>
	    </question>
	    <answer>
		<para>
			Take a look at &serhomelink;.
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>Where can I post a question about this module?</para>
	    </question>
	    <answer>
		<para>
			First at all check if your question was already answered on one of
			our mailing lists: 
		</para>
		<itemizedlist>
		    <listitem>
			<para>User Mailing List - &seruserslink;</para>
		    </listitem>
		    <listitem>
			<para>Developer Mailing List - &serdevlink;</para>
		    </listitem>
		</itemizedlist>
		<para>
			E-mails regarding any stable &ser; release should be sent to 
			&serusersmail; and e-mails regarding development versions
			should be sent to &serdevmail;.
		</para>
		<para>
			If you want to keep the mail private, send it to 
			&serhelpmail;.
		</para>
	    </answer>
	</qandaentry>
	<qandaentry>
	    <question>
		<para>How can I report a bug?</para>
	    </question>
	    <answer>
		<para>
			Please follow the guidelines provided at:
			&serbugslink;.
		</para>
	    </answer>
	</qandaentry>
    </qandaset>
</chapter>

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