Open-Source Network Management Tools

["Claydon, Tom" <Tom.Claydon () DobsonTelco net>]

I'm looking for open-source alternatives for network management, such as
Nagios or Big Brother. We are currently using WhatsUp Gold, and would
like to move to something more flexible (and not running on a Windows
platform). Something that has email/paging capabilities, and can process
SNMP traps would be a plus for us as well.

Recommendations?

Thanks.