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access_control

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Access Control Strings

Access Control Strings (or ACS) are found all over Mystic BBS and are used to control the who, what, and when of security access to various parts of your BBS. Every menu, menu command, any many other functions in the BBS have an associated ACS definition which the SysOp can use to create and apply find-grained access control to all elements of the BBS.

The ACS system is designed to allow for the most intricate security controls without requiring programming, and consists comprised of a series of “functions” that either result in being True or False. At the end, if all functions in an ACS are True, that means the user has access.

Each ACS function is nothing more than a single character, most often followed by a parameter afterwards that supplements the function. The most basic example of this would probably be an ACS of “s20”. An ACS of “s20” uses the function “S” which means security level, followed by 20, which defines is parameter. The result of this ACS is that the user must have a security level of 20 or higher to have access.

In addition to this basic function and parameter system, ACS can use parenthesis to force an order of evaluation, and also has the typical Boolean operators AND OR NOT that can be used along with them. Let's look at one example of a more complex ACS before we move on:

   (s20!s21|s255)|u10|(h22!h23)
   

The above ACS says that the user must have ANY one of the following things to have access:

     User must have a security level of at least 20 but NOT 21 or higher
     (exactly level 20), OR they can have a security level of 255.
     
     OR
     
     User must be user ID #10 who may be a specific person you may want
     to have access regardless of any other parameters
     
     OR
     
     The user must be accessing the command between 10pm and 11pm.

Now that we've had a little introduction to the ACS lets look at a reference of the ACS functions and their parameters:

        Ax  -  This command is used to check the user's age.  Where X is
               the age the user must be in order to pass.
        Dx   - This command is used to check if a user has a certain flag
               toggled ON in their SECOND set of flags.  Where X is the
               flag which the user must have in order to pass.  For
               example: DA will require the user to have user access flag
               D in flag set 2 in order to pass.
        Ex  -  This command is used to check the user's current graphics
               mode.  Where X is one of the following:
                    1 - User must have ANSI graphics
                    0 - User must have ASCII (none) graphics.
        Fx  -  This command is used to check if a user has a certain flag
               toggled ON in their FIRST set of flags.  Where X is the
               flag which the user must have in order to pass.  For
               example: FA will require the user to have user access flag
               A in flag set 1 in order to pass.
        Gx  -  This command is used to check if a user is in a certain
               message group.  Where X is the number of the group as listed
               in the message group editor.  For example: G1 will require
               the user to be in message group #1 in order to pass.
        Hx  -  This command is used to check if a user is accessing
               a command at a certain hour.  Where X is the hour in the
               24-hour mode (ie 00 is midnight or after, 23 is 11pm or
               after).  For example: H12 will prevent the user from
               accessing this command before 12 noon on any given day.
        Nx  -  This command is used to check if a user is online a
               certain node number.  For example: N1 will require that
               the user is currently logged in on Node 1 in order to
               pass.
        OA  -  This command is used to check the status of the user's
               node message availibility.  If the user is able to
               receive node messages, OA will return true.  False if
               they are not available.
        OI  -  This command is used to check if a user's node status
               is invisible to other nodes.  It will be set TRUE if
               the user is invisible, false if not.
        OK  -  This command is used to check the result of the last
               called Boolean menu command.  For more information, see
               the menu commands: -P, -Y, and -N.
        OP  -  This command is used to check the status of the user's
               post / call ratio.  If the user meets the currently set
               ratio, then OP will be true - otherwise, if will return
               false.  This option is useful to restrict users from
               downloading if they're not active message posters.
        Sx  -  This command is used to check if a user meets a certain
               security level.  For example: S20 will require the user
               to have a security level of 20 or higher in order to
               pass.
        Tx  -  This command is used to check if a user has at least
               X minutes remaining in online time.  For example: T10
               would require the user to have a least 10 minutes of
               remaining time in order to pass.
        Ux  -  This command is used to check a user's permanent user
               number, where X is the number of the permanent index the
               user must match.  For example: U1 would require the user
               to have the permanent user index of 1.  Each user's
               permanent index is listed in the user editor, and no two
               users will ever have the same permanent index number.
        Zx  -  This command is used to check if a user is in a certain
               File Group.  Where X is the number of the group as listed
               in the File Group editor.  For example, Z1 will require
               the user to be in File Group #1 in order to pass the ACS
               check.
   Any of the above commands can be used together to create an ACS string
   used by Mystic BBS.  Below are some examples of how they can be used:
        s255     - User must have security of 255 or higher.
        s255n1fA - User must have a security level of 255 or higher, be
                   currently logged into Node 1, and have user flag A
                   toggled on, in order to pass this ACS string.
        s10z1h12 - User must have a security level of 10 or higher,
                   be currently in File Group #1, and be accessing this
                   function after 12:00 noon, in order to pass this
                   ACS string.
   For added flexibility, Mystic also supports five logical operators
   which can be used in ACS strings:
        & = Logical AND
        | = Logical OR
        ! = Logical NOT
        ^ = Always TRUE
        % = Always FALSE
   In addition to the operators, Mystic BBS also allows parenthesis in ACS
   strings to allow evaluation of grouped ACS commands.  Some examples of
   using operators and grouping are:
        ^               Always returns TRUE.  Grants access to ALL users.
        %               Always returns FALSE. Grants access to NO users,
                        not even the SysOp.
        s10!s20         User must have a security level which is at least
                        10 but NOT 20 or greater.
        t20|s255        User must have 20 minutes of time remaining, OR
                        have a security level of 255.
        !(s255|fa)      User must NOT have a security level of 255 and flag
                        A toggled on.
        (s20fa)|(s255)  User must have a security level of 20 with flag A
                        toggled on, *OR* have a security level of 255 or
                        higher.
   As you can see, the access command system gives Mystic BBS an
   incredible amount of flexibility when it comes to system security!
access_control.1458665438.txt.gz · Last modified: 2016/03/22 12:50 by g00r00