The collected works of Ravege

Hey guys, contemplating dusting the dust off my SGI boxes. Looking for some ideas on securing, or improving security, or generally hardening the machines. I haven't worked with any UNIX for awhile, so even general/not IRIX specific stuff would be great. Thanks!
:Octane: 2x600 R14K, 8G, V12
:O2: 1x600 R7K, 1G
:Indigo2IMP: 1x75 R8K, 256M