This is an old article about SCO Unix security levels and is only left here for historical purposes.
There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.
It is not traditional Unix security without the TCB. Rather, it uses the TCB to achieve a level of security lower than traditional Unix security. For example, it gives all users the privileges to administer print services, backups/restores, and to run shutdown. The moral is not to use low security unless you know the security holes it opens and can live with them. The "traditional" security level is the closest to traditional Unix security, and should probably be the lowest security level that most people should consider using. The next level up is similar to C2 security as found in prior releases of SCO Unix, while the top level is tighter yet.
Note that each of the four security levels, as with the two levels in earlier releases, is only a set of defaults. Once you have installed a particular security level, you can adjust the exact settings to make security suit your needs. Note that once a system has been set up at a particular security level, it may be difficult or impossible to completely increase the security level, particularly if the system has been in use for some time.
Got something to add? Send me email.