1. Custom SNMP OID Creation for System Monitoring Robert V. Bolton robert.bolton@utah.edu

2. About Robert V. Bolton Systems Administrator Center for High Performance Computing @ University of Utah Mac Desktops, Linux Servers, HP Networking Infrastructure Monitoring: Nagios and Cacti Pyton Coder Nagios Plugins and Cacti Scrtips Student Computer Engineering or Electrical Engineering Expected Graduation = ? Geek Board Game Enthusiast Amateur Radio Operator (KE7ZEA) www.robertvbolton.com

3. What we’re going to cover today. Why Bother Creating Custom OIDs OID Tree Structure Python Module: snmp_passpersist Real World Example: IOStat Statistics

4. Why Bother Creating Custom OIDs SNMP is “simple” to use to gather system statistics. Nagios Plugins work great with Nagios, but may not provide data to other monitoring software. Example: NRPE Remote Execution. Offload Time Consuming System Checks. Provides Statistics for things not normally provided by in the SNMP tree.

5. OID Tree Structure • SNMP uses a hierarchical tree structure

6. OID Tree Structure Conitued • Numbers are used to locate information • Each number corresponds to a specific branch of the OID tree. • Management Information Base (MIB) files map OID numbers to human readable format • .1.3.6.1.4 is the top of the private branch • Vendor OIDs • Our Custom OIDs

7. Python Module: snmp_passpersist • Why Python…Because I know Python! • I believe it is possible to create OIDs with Perl as well if your prefer. • Github: nagius/snmp_passpersist • Requires Net-SNMP • Installation is easy: Download source, python setup.py install, and you’re done. • Import: import snmp_passpersist as snmp

8. Python Module: snmp_passpersist contiued #!/usr/bin/python -u import snmp_passpersist as snmp from commands import getoutput base_oid=".1.3.6.1.4.1234.1.3" defget_file_systems(): file_systems = getoutput("df -iP | awk '{print $1}'").split('\n') file_systems.remove('Filesystem') return file_systems defget_inode_count(): inode_count = getoutput("df -iP | awk '{print $3}'").split('\n') inode_count.remove('IUsed') return inode_count def update(): file_systems = get_file_systems() inode_count = get_inode_count() counter = 0 for x in file_systems: counter += 1 pp.add_int("1.%s" % str(counter),counter) pp.add_str("2.%s" % str(counter), x) counter = 0 for x in inode_count: counter += 1 pp.add_gau("3.%s" % str(counter), x) pp=snmp.PassPersist(base_oid) pp.start(update,60)

9. Python Module: snmp_passpersist contiued Add to /etc/snmp/snmpd.conf pass_persist .1.3.6.1.4.1234.1.3 /usr/local/bin/inodeCount.py Results SNMPv2-SMI::private.1234.1.3.1.1 = INTEGER: 1 SNMPv2-SMI::private.1234.1.3.1.2 = INTEGER: 2 SNMPv2-SMI::private.1234.1.3.1.3 = INTEGER: 3 SNMPv2-SMI::private.1234.1.3.2.1 = STRING: "/dev/mapper/winkler-root" SNMPv2-SMI::private.1234.1.3.2.2 = STRING: "/dev/sda1" SNMPv2-SMI::private.1234.1.3.2.3 = STRING: "tmpfs" SNMPv2-SMI::private.1234.1.3.3.1 = Gauge32: 355793 SNMPv2-SMI::private.1234.1.3.3.2 = Gauge32: 48 SNMPv2-SMI::private.1234.1.3.3.3 = Gauge32: 1

10. Real World Example: Iostat • Problem • User: “The network is slow!” • Support: To many users hammering on a file system • Solution Requirements • Present Users with easy to read graphs of disk statistics. • Allow for Nagios monitoring of disk statistics • Minimal Impact of monitoring because of Iostat

11. Real World Example: Iostat • Iostat • First output from Iostat is garbage. • Cron Job runs Iostat and stores the results in a temp file • Python Script iostat.py • Reads results from temp file and uses snmp_passpersist to update a custom branch of OID tree. • SNMP OID • Data accessible to both Nagios and Cacti.

12. Thank you! www.chpc.utah.edu Questions? Robert V. Bolton robert.bolton@utah.edu