What are some good Linux server management programs?
I'm looking for some tools to help me get a better grasp of our RedHat and Ubuntu servers. I'm mostly a Windows guy so let me know if there are some nice gui-based apps out there. Open source is good because I don't really have a budget.
The best tool I've found for managing servers and services across the network is Nagios. It may take a little bit of time to wrap your head around it, but it's essential for maintaining a large and diverse network.