Managing an OpenSim installation with only the tools offered by the console is possible and for some tasks necessary, but especially when it comes to user administration it can be a bit tedious. So at some point or the other every prospecive OpenSim administrator will reach the point where he or she needs to look for a webgui to manage as much as possible. A commercial grid with sufficient funding might be able to pay for a custom development, but most will look for a standard tool that also integrates into a cms.
When talking about OpenSim- and Hypergrid-security I believe several aspects have to be taken into account it is not enough to secure the server and leave the Hypergrid door wide open or vice versa.
On the local side basically all average grid owners can do, is to take basic measures like a firewall and ensuring their system is up to date. It would be advisable though to go a step beyond the usual and use programs like portsentry or fail2ban to thwart and block the casual hacker. If you really have a determined and knowledgable hacker there is not really much you can do to keep him or her out.