As part of the LinuxServer project, and more importantly as part of my job, I've been looking at configuring and setting up a "security server".
Small to medium businesses.
A number of Hamilton IT companies with Wiki-associated staff have built or sold firewall systems based on RedHat Linux. One uses a KickStart install, one simply untars its filesystem etc. A standardised system would be easier for everyone involved, would make updating much easier (DebianLinux and apt(8) instead of Red Hat), and would generally make me a happy person.
The reasoning behind a "security server" derives from the fact that one firewalling paradigm is to run a firewall with no services whatsoever, and another is to run it on the same machine as some of your servers. A small company only has one IP which can only be terminated on the firewall (and some services don't NAT well). A small company can't afford to have lots of discrete servers. So. due to these practical concerns, you have to run a few services on your internet facing machine. (Dangerous ones may be chosen to be run only internally)
This system is designed to work with a LinuxServer (or as excellent first line protection for a Windows server) and provide all the security related functions for the network, leaving the central server to do the mail/files/whatever.
This server shouldn't share a common user auth with the rest of the network.