SNMP traps are sent by SNMP-capable devices to specified servers when a significant event occurs. SNMP trap servers then decide how to process and handle the event. For example, a trap server can e-mail a network administrator. This is useful for network administrators who want to receive alerts quickly, rather than wait for a potentially long polling cycle to complete.

To specify a trap server in pfSense, take the following steps:

1. Navigate to Services | SNMP.
2. Check the Enable SNMP Traps checkbox.
3. Enter the trap server hostname in the Trap Server Name edit box.
4. Enter the port in the Trap Server Port edit box.
5. Enter a string in the Trap Server String edit box.
6. Click on the Save button.