I have 10 servers for administration bacially the servers are prim/sec dns, 3 radius, 1 web server, 1 firewall, 1 backup, 1 mail server with 1 antispam/antivirus. All servers are running redhat/centos and I have 10 server plesk license but only on one server it is installed. I need server maintenance and administration and some hardening if needed. No client part interaction. I just need this servers to be 100% uptime,maintened regularly (kernels, rules, patches ..)and fixing any problems that might occur.