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Using ipMonitor's SNMP - QA Monitor and the NET-SNMP Daemon, Administrators can monitor the file size of a specified file on a Unix-based Operating System.

	Net-SNMP is a suite of applications used to implement SNMP v1, SNMP v2c and SNMP v3 using both Internet Protocol (IP) version 4 and Internet Protocol (IP) version 6.
Net-SNMP is available for many Unix and Unix-like operating systems and also for Microsoft Windows. Detailed information on downloading and configuring the Net-SNMP daemon is available from the Net-SNMP website.

Before configuring SNMP - QA Monitors to implement the examples outlined in this tutorial, the Net-SNMP Daemon must be installed and configured on each machine being monitored.

Important! You must add the FILE directive to your snmpd.conf file. The FILE directive increases the indexed OID values. For every FILE directive entered, the OID index value will increment by one (1). A maximum of 20 files can be listed.

Directive:
FILE <path/filename>

Examples:
FILE /var/apache/logs/access_log
FILE /var/apache/logs/error_log
FILE /etc/sma/snmp/snmpd.conf

For detailed information on performing this step, please refer to the following Net-SNMP resources:

http://net-snmp.sourceforge.net/docs/man/snmpd.conf.html

http://net-snmp.sourceforge.net/docs/man/snmp_config.html

	Click the XML icon to download resources designed to be used with this tutorial. The XML file includes three preconfigured Monitors, as well as a predefined Group for the Monitors.
	To incorporate the Cisco MIBs described in this article into your ipMonitor installation, access the SNMP MIB Database Builder located within the ipMonitor Support Portal. Note: Custom databases are only available to registered customers. You must log in to access this section. 1. Expand the Enterprise branch, and place a checkmark beside NetSNMP. 2. Click the Construct MIB Database button located at the bottom of the page. Shortly after selecting your custom MIBs for creation, you will receive an email indicating that your database is ready for download. This email will contain a link to your personalized SNMP MIB database. Additionally, each visit to the Support Portal home page will also contain the link to your most recently created database.
	Click the PDF icon to open a printable PDF version of this tutorial. It includes all the information found here, including images from the ipMonitor software, diagrams, and links to additional resources.

Monitor 1

Monitor Name	NET-SNMP Daemon :: File Size [access_log - Index 1]
Monitor Type	SNMP - QA Monitor
SNMP Object Type	fileSize.1
OID	1.3.6.1.4.1.2021.15.1.3.1
Returns	The current size of the specified file in kilobytes [KB].
Monitoring Condition	Pass if less than 100000 Monitor failure indicates that the file has grown larger than 100KB.

Monitor 2

Monitor Name	NET-SNMP Daemon :: File Size [error_log - Index 2]
Monitor Type	SNMP - QA Monitor
SNMP Object Type	fileSize.2
OID	1.3.6.1.4.1.2021.15.1.3.2
Returns	The current size of the specified file in kilobytes [KB].
Monitoring Condition	Pass if less than 75000 Monitor failure indicates that the file has grown larger than 75KB.

Monitor 3

Monitor Name	NET-SNMP Daemon :: File Size [snmpd.conf - Index 3]
Monitor Type	SNMP - QA Monitor
SNMP Object Type	fileSize.3
OID	1.3.6.1.4.1.2021.15.1.3.3
Returns	The current size of the specified file in kilobytes [KB].
Monitoring Condition	Pass if equal to 3KB Monitor failure indicates that the size of the file does not equal 3KB.

Note: All imported Monitors are initially disabled. This allows you to make changes to the default settings before the Monitors are enabled to go live in a production environment. Once the Monitors are imported, the following settings will need to be verified (and if necessary, modified) for each Monitor:

• IP Address
• UDP Port
• Community

To learn more about modifying the above parameters, please refer to the 'Configuring the SNMP - QA Monitor' section of this tutorial.

TIP For detailed instructions regarding importing XML files into your ipMonitor installation, please refer to the tutorial entitled "How to Import and Export Configuration Settings".

For the purposes of this tutorial, we'll be referring to the preconfigured Monitors included in the XML resource download. Alternatively, you can create a new Monitor by clicking the Monitors menu option and then selecting Add a Monitor. Choose the SNMP - QA Monitor from the Multi-Transaction / QA category.

1. Enter a unique, descriptive name for the Monitor in the Name field.
2. Choose whether to automatically add the new Monitor to a particular Group.
3. Check the Enabled checkbox.
4. Choose whether you want the Monitor to Store Monitor Statistics for Recent Activity and Historical Reports.

5. Specify the location of the SNMP Service (in this case, the Net-SNMP Daemon). Both IP Address and Domain Name are valid entries.
6. If needed, specify a different UDP Port Number for the SNMP Service. By default, the standard Port Number used for SNMP communication (Port 161) is already entered.
7. If you are using one of the preconfigured Monitors, the appropriate OID for the monitoring task is already entered. Otherwise, you will need to specify an OID path in the OID field.
8. Enter the SNMP Community string that allows ipMonitor to communicate with the SNMP Service.
9. Select the SNMP Version used by the device to be monitored. Both ipMonitor and the target device must use the same SNMP Version. Available options are: SNMP Version 1 and SNMP Version 2.

The following example uses the Analysis of Test Results settings configured for the 'NET-SNMP Daemon :: File Size [error_log - Index 2]' Monitor provided in the XML resource download.

The type of data supported by the selected OID determines the possible methods of analysis using the SNMP - QA Monitor.

1. In order to return the desired value (the size of the specified file), the SNMP - QA Monitor is configured to analyze the result as Numeric Data.
2. The expected result is determined to be less than (<) 750000, ensuring that the Monitor will pass if the returned data indicates that the file size is less than 75KB.

TIP By default, the Timing Intervals for each parameter are set to 300 seconds. If needed, adjust these defaults to meet your specific monitoring environment's requirements until the optimum settings are reached.

For more information regarding the SNMP - QA Monitor, refer to the Monitors section of ipMonitor's Context-Sensitive Help system, and then select Monitor Types, followed by SNMP - QA. The Context-Sensitive Help can be accessed by clicking the Help link located in the top right corner of ipMonitor's Administration web interface.

For information on other features and concepts related to those discussed in this article, refer to the following ipMonitor resources:

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Last Updated: April 11, 2006 | What did you think of this topic?