Using Nagios and SNMP to monitor network devices

Usage:

check_snmp 

-H <ip_address>
-o <OID>
[-w warn_range]
[-c crit_range]
[-C community]
[-s string]
[-r regex]
[-R regexi]
[-t timeout]
[-e retries]
[-l label]
[-u units]
[-p port-number]
[-d delimiter]
[-D output-delimiter]
[-m miblist]
[-P snmp version]
[-L seclevel]
[-U secname]
[-a authproto]
[-A authpasswd]
[-x privproto]
[-X privpasswd]

Note:

the -c and -w (critical and warning ranges respectively) reflect ranges differently depending on if you want a critical to be low (under 10 for example) or high (over 90). In the former case, say the Signal Level of a microwave device you are monitoring is critical when under 10% and warning under 20% then the format of the -w and -c would be:

            -w 25: -c 10:

If on the other hand you are looking at Signal to Noise ratio where warning is 50 dB and critical is 75 dB then the command would be:

            -w :50 -c :75

If you have say a table where numbers translate to other things, again using a Microwave example:

wvSubDataRate  OBJECT-TYPE
               SYNTAX      INTEGER {
                              rf-bw-1p5-Mbps(1),
                                                          rf-bw-2p25-Mbps(2),
                                                          rf-bw-3-Mbps(3),
                                                          rf-bw-4p5-Mbps(4),
                                      rf-bw-6-Mbps(5),
                                      rf-bw-9-Mbps(6),
                                      rf-bw-12-Mbps(7),
                                                          rf-bw-13p5-Mbps(8),
                                      rf-bw-18-Mbps(9),
                                      rf-bw-24-Mbps(10),
                                                          rf-bw-27-Mbps(11),
                                      rf-bw-36-Mbps(12),
                                      rf-bw-48-Mbps(13),
                                      rf-bw-54-Mbps(14),
                                      rf-bw-72-Mbps(15),
                                      rf-bw-96-Mbps(16),
                                      rf-bw-108-Mbps(17)
                           }
               MAX-ACCESS  read-only
               STATUS      current
               DESCRIPTION
                    "The data rate of the station."
               ::= { wvSubStatusEntry 4 }            

and you'd like to have the actual data rate instead of the number then you need to tell it what MIB to use by putting the -m switch at the end e.g.

-m MWAVE-MIB and it will translate the output (typically just a number like "15 = rf-bw-72-Mbps) - giving you meaningful output.

That's it for now but more to follow as I keep working with this type of hardware.