SNMP

MIB Explorer

MIB browser shows all loaded MIB configurations, and allows to run SNMP walk on a selected node nodes. Node can be selected in browser by selecting Set node object… option in view menu or by opening MIB Explorer from node menu.

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To run walk user should select line of tree from were will be requested all data. By walk will be requested all OID subtree of selected item.

After walk is done it’s results will shown in the table below.

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There are next options available for results:
  • Copy result line to clipboard
  • Copy name of selected line to clipboard
  • Copy type of selected line to clipboard
  • Copy value of selected line to clipboard
  • Export selected lines to CSV
  • Show selection in MIB tree
  • Create DCI form selected item

SNMP Trap Configuration

In this view is configured which event will be generated on exact trap OID and which OID data will be used as event parameter data.

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In SNMP Trap mapping configuration window can be set next parameters:

  • Description of mapping rule
  • Trap OID or trap OID group with many subtree OIDs, matching OID will be given to event as $1 parameter
  • Event that will be generated on selected Trap OID
  • User Tag is special event attribute, that can be got by %u macros or as attribute of event class. This attribute can be set there or by script.
  • Parameters - OID values that will be passed to event as $2, $3, $4… parameters

In parameter configuration(Edit SNMP Trap Parameter Mapping) can be configured next things:

  • Description of a parameter
  • Select if parameter should be found by OID or by position in the message
  • Option not to convert value to hex string. If string contains not readable symbols(symbol number less than space symbol number) it will be automatically converted to hex string, this option is required to prevent auto conversion.
_images/snmp_trap_mapping_configuration.png

Default SNMP credentials

Default SNMP credentials can be set in Configuration ‣ SNMP Credentials. It does not matter if credentials are used for adding nodes manually, through network discovery or with the help of agent registration - in each case SNMP Credentials configuration value will be checked.

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Using ifTable and ifXTable

There are 2 types of subtree that provides information about interfaces: old one ifTable and new one ifXTable. Sometimes usage of new one creates error situations. In this situation ifXTable can be disabled. This can be done in Properties of node in Polling. Or this configuration can be set globally by changing UseIfXTable server configuration parameter.

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Configure SNMP Proxy

If there is need to monitor nodes behind firewall using SNMP, there is option to install on one of the nodes NetXMS agent, open all required ports for this node and send SNMP request to other nodes in this subnet through installed agent.

Proxy configuration can be done wile creation of node of for already created node can be change in Communications tab of node properties. To configure proxy node select node in object selector SNMP Proxy.

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Agent configuration

To enable SNMP proxy “EnableSNMPProxy” parameter should be set to “yes”.

Configure SNMP Trap Proxy

It is possible to proxy SNMP traps.

In this case as a destination of traps should be set the proxy node.

Agent configuration

To enable trap proxy “EnableSNMPTrapProxy” parameter should be set to “yes”.

Optionally can be configured also “SNMPTrapListenAddress” and “SNMPTrapPort”. Default values can be checked there: Master configuration file

Server configuration

By default traps are accepted only from known nodes. To accept all traps set “LogAllSNMPTraps” server configuration variable to 1.

To correctly send response for SNMPv3, it should be also configured the proxy node for the sender node. It is done in sender node properties in “Communications” tab, SNMP section.

Import MIB

MIB files (MIBs) describe structure of information transferred via SNMP. Every device can support multiple MIBs, some of them are standard and public, other can be proprietary and vendor specific. NetXMS uses compiled MIBs to allow you to select OID and see its description (for example when selecting SNMP data for DCI collection). You do not need to compile new MIBs if you are OK with direct input of OID.

Compiling MIBs

  • Change suffix of your new MIB file to .txt
  • Copy your MIB file to /usr/share/netxms/mibs
  • Use nxmibc binary to create a new compiled MIB file from all MIBs in directory. Add parameter -z for compressed output file.
nxmibc -d /usr/share/netxms/mibs -o /usr/share/netxms/mibs/netxms.mib

Parameters recognized by nxmibc:

nxmibc [options] source1 ... sourceN

Valid options:
  -d <dir>  : Include all MIB files from given directory to compilation
  -o <file> : Set output file name (default is netxms.mib)
  -P        : Pause before exit
  -s        : Strip descriptions from MIB objects
  -z        : Compress output file

Troubleshooting

If nxmibc fails, it may be caused by syntax or import errors in your MIB. Try to check it with smilint (part of net-snmp package) and correct any errors on level 3.