Capture Network Device Information Using Casper

November 9th, 2012 by William Smith

JAMF Software’s Casper suite is designed to capture and store information about Mac and Windows clients. However, it can also store information about network resources such as printers and routers by using a server or workstation as a pseudo SNMP Network Management Station. The following example illustrates how to use a Casper Extension Attribute to store the uptime of an Airport Extreme base station in a managed client’s record in the JAMF Software Server (JSS).

Uptime is the length of time a device has been active since its last reboot. An Airport Extreme base station should have a relatively long uptime (weeks or months) compared to a workstation (days). If the uptime of a base station is always just a few days then that may indicate hardware failure or power problems.

First, using the snmpwalk command, a server or workstation can poll the public community of any Airport base station at its IP address:

snmpwalk -v1 -c public -M /usr/share/snmp/mibs

This command will return a lot of information. Applying grep to return just the sysUpTime information and cut to trim away  everything but the value of sysUpTime, the final result looks something like:

$ snmpwalk -v1 -c public -M /usr/share/snmp/mibs
-m AIRPORT-BASESTATION-3-MIB | grep sysUpTime | cut -d \) -f 2

286 days, 10:38:38.70

An extension attribute is simply a shell script that runs a command to gather information and then returns that information to be stored in the JSS. Every managed computer in the JSS runs these scripts during routine inventories. But only one should be dedicated to polling the base station and storing the uptime information.

During a routine inventory this script verifies whether the name of the computer in the script matches the name of the current computer. If they match then it runs the snmpwalk command to poll the base station for its uptime.

To add this as an extension attribute in the JSS:

  1. Navigate to Settings tab –> Inventory Options –> Inventory Collection Preferences –> Extension Attributes tab –> Add Extension Attribute.
  2. Name this Extension Attribute “Airport Uptime”.
  3. Set the Data Type to String.
  4. Set the Input Type to Script and paste in the script.
  5. Edit the script by entering the name of the computer that should poll the Airport base station.
  6. Enter the IP address of the Airport base station in the script as well.
  7. Click the OK button and then Save the Extension Attribute.

Run the Recon application on the polling computer to update its inventory in the JSS. When done the EA should return the uptime for the base station to the computer’s record.

To view the information search for the computer in the JSS and click its Details link. Click the Extension Attributes section on the next page and locate the “Airport Uptime” Extension Attribute on the right.

Update: John C. Welch has written a companion piece to this post outlining some better and more efficient ways to accomplish the SNMP polling: A companion post to a 318 post. Thanks for the writeup, John!

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