Essential SNMP, 2nd Edition

Sending Traps

By now you should have a mechanism in place for receiving traps. In this section, we'll look at some different utilities that send traps and allow you to develop traps that are appropriate for your environment. You'll notice that almost all trap utilities are command-line based. This allows you to execute the command from within a script, which is almost always what you want to do. For example, you can write a shell script that checks disk space every five minutes and sends a trap to the NMS if you're running low. You can also use these trap generators within existing programs and scripts. If you have a Perl script that accesses a database, you can use the Perl SNMP module to send a trap from within the script if a database insert fails. The possibilities are almost endless.

Although there are many different snmptrap programs, they are all fundamentally similar. In particular, though their command-line syntax may vary, they all expect roughly the same arguments:

Port

The UDP port to which to send the trap. The default port is 162.

SNMP version

The SNMP version appropriate for the trap you want to send. Many traps are defined only for Version 2. Note that many SNMP tools support only Version 1.

Hostname or IP address of NMS

The hostname or IP address of your NMS—i.e., the trap's destination. It is better to use an IP address than a hostname in case you are sending traps during a DNS outage. Remember that SNMP is most valuable when your network is failing; therefore, try to ...