Chapter 7. SNMP
SNMP can change your life as a sysadmin. The rewards of using SNMP are not as instantaneous as writing a few lines of Python to parse a logfile, for example, but when an SNMP infrastructure has been setup, it is amazing to work with.
In this chapter, we will be covering these aspects of SNMP: autodiscovery, polling/monitoring, writing agents, device control, and finally enterprise SNMP integration. Of course, all of these things are going to be done with Python.
If you are unfamiliar with SNMP or need to brush up on SNMP, we highly recommend reading Essential SNMP by Douglas Mauro and Kevin Schmidt (O’Reilly), or at least keeping it handy. A good SNMP reference book is essential to truly understanding SNMP and what it can do. We will go over a few of the basics of SNMP in the next section, but going into much detail is beyond the scope of this book. In fact, there is more than enough material for a complete book on using Python with SNMP.
Brief Introduction to SNMP
The 10,000 foot view of SNMP is that it is a protocol for managing devices on an IP network. Typically, this is done via UDP ports 161 and 162, although it is possible, but rare, to use TCP as well. Just about any modern device in a data center supports SNMP; this means it is possible to manage not only switches and routers, but servers, printers, UPSs, storage, and more.
The basic use for SNMP is to send UDP packets to hosts and to wait for a response. This is how monitoring of devices ...