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opsview4.6:snmptroubleshooting [2014/09/09 12:19] (current)
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 +====== Troubleshooting SNMP monitoring ======
 +Configuring SNMP for network monitoring can be a headache. This document describes some common problems and fixes.
 +
 +===== Configuring SNMP agent =====
 +
 +
 +SNMP software running on a network device is referred to as a 'SNMP agent'.
 +
 +
 +Although every network device has a different configuration process the following steps are usually required. Instructions are for SNMP versions 1 and 2. If you're using SNMP v3 we'll assume you're already an expert :)
 +
 +
 +== SNMP version ==
 +
 +Set SNMP version to either v1 or v2c. If no option exists for 'v2c' then try 'v2'.
 +
 +== SNMP community ==
 +
 +The SNMP community acts like a password. Default is often set to 'public' and we strongly recommend this is changed.
 +
 +== Read Only or Read Write permissions ==
 +
 +Opsview requires only 'read only' access (RO). We recommend you don't set greater level of permissions than you actually need.
 +
 +== Access Control ==
 +
 +Most devices have some form of access control. Usually this involves specifying the IP address of your monitoring server. Beware if you're using Network Address Translation (NAT) on your network.
 +
 +===== Configuring Opsview =====
 +
 +In Opsview, SNMP settings are contained in the Host configuration form. From left navigator select Configuration -> Hosts and edit a host. In the host configuration, you need to select the SNMP tab.
 +
 +{{opsview4.6:host_snmp_tab.png|}}
 +
 +  * Set correct SNMP version. Most plugins will use SNMP version 2 and then fallback to 1, but it will be quicker and more correct to choose the correct version
 +  * Set correct community. There will be more security options if SNMP version 3 is selected.
 +
 +'Query host' option allows you to confirm settings are correct as it queries the host with the credentials and returns back information about the device and the interfaces on it.
 +
 +===== Configuring firewall =====
 +
 +If a firewall sits between monitoring server and SNMP agent you must ensure SNMP traffic can pass.
 +
 +== Opsview to SNMP agent ==
 +
 +Communication from Opsview to SNMP agent is via UDP port 161
 +
 +== SNMP agent to Opsview ==
 +
 +If you're intending to process SNMP traps it will be necessary to allow communication from SNMP agent to Opsview server. SNMP traps use UDP port 162.
 +
 +===== Common problems =====
 +
 +== Nagios plugin responds with 'Agent not responding, tried SNMP v1 and v2c' ==
 +
 +Essentially this means plugin could not communicate with with SNMP agent. We recommend you check settings in Opsview and on device. Also check your firewall settings.
 +
 +== Intermittent 'time out' problems with Nagios plugin ==
 +
 +If you're experiencing intermittent 'time out' errors with Nagios plugin try the following:
 +
 +  * Increase value of 'time out' argument for plugin. Most plugins support this option and it will force the plugin to wait longer for a response from SNMP agent.
 +  * It is possible to overload the SNMP agent with requests. If you increase polling interval or reduce number of service checks against device it may help.
 +  * Check firewall logs for indication that it may be dropping SNMP traffic - assuming there is a firewall between Opsview and SNMP agent.
 +
 +===== SNMP tools =====
 +
 +Net-SNMP package should be installed as a pre-requisite package for Opsview software. This package includes some helpful command line tools for diagnosing SNMP issues. More information can be found on Net-SNMP website:
 +
 +http://net-snmp.sourceforge.net/docs/man/
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