Unfortunately (or not), Windoze based. My experience with it started out unstable and feature poor at version 4, but it kept the relatively inexpensive (core, support, and add-on) price tags, and features kept getting better, and stability continues to improve at version 7.1. Remote windows and java consoles, remote pollers, SNMPv3, easy custom MIB compiles, functional dependencies, device grouping, custom alarms, restricted console views, packaged third party paging and email, custom tool integration, easy maps, acceptable (to me) TCP service monitoring and third party script support. Reporting is also integrated, or use the up-featured SQL add-on. I'm using it for just shy of a couple thousand devices on a single modest server. It's been able to accommodate every NMS feature I need, and a great many wants. My only real gripes are: console authentication still doesn't have a RADIUS, LDAP, or AD hook, and I'd like a Linux port for the backend. Other than that, it's shamefully simple to get new staff up and running, and it requires very little care and feeding. Good luck with your search.