Lesson 3 File and Group Security

• file security in your home group

• file security in the PUB group

• file security in other groups

• The file you want to work with has been released with the RELEASE command.

• The group in which the file is located is either the PUB group or your home group.

• The file is protected by being locked with a lockword.

• The file is protected by some other system security measure.

File security in your Home group

With only the default set of capabilities, you can always access (read, change, save) any file in your home group, no matter what group you log on to.

File Security in PUB

With only the default set of capabilities, you can at least read (and probably change) any file in the PUB group, no matter what group you log on to. But in most cases, you cannot then save that file back to the PUB group unless you have advanced capabilities, or unless the file has been released with the RELEASE command.

You can, however, save this "borrowed" file to your current group, the one in which you are actively working.

Using your logon identity, log on to your PUB group:

   HELLO username.accountname,PUBReturn

	NOTE: The following exercise only works if you do not have AM capability.

Create an EDIT/3000 file that contains the following three lines:

   This is the file called REPORT.

   It is very short.

   The end.

Keep this file as REPORT and exit the editor.

Log on to your OTHERGRP group:

   HELLO username.acctname,OTHERGRPReturn

Get into the editor again:

   EDITORReturn

Try to text in REPORT:

   TEXT REPORTReturn

The problem is that REPORT is in the PUB group, and you are now in OTHERGRP.

MPE/iX assumes that the file that you want to work on is in your current logon group. To tell MPE/iX that REPORT is in another group, you need to specify the REPORT file with a partly qualified file name.

A partly qualified file name is the file name plus a period plus the name of the group in which the file resides. The partly qualified form of REPORT is REPORT.PUB

Do this:

   TEXT REPORT.PUBReturn

Because the REPORT file is located in the PUB or public group, you are able to access and text it into your work session in the OTHERGRP group.

Enter:

   LIST ALLReturn

Add the following lines to the REPORT file. (Use the ADD subcommand.)

   This is the REPORT file in the PUB group.  

The goal now is to save (KEEP) REPORT back to the PUB group.

The problem is that you are still in group OTHERGRP. Do this:

   KEEPReturn

The editor remembers that the file came from the PUB group, so it attempts to save the edited version of the file back to the PUB group.

Enter YES when you are asked whether to purge the old REPORT file.

This should appear on the screen:

   REPORT.PUB REPORT.PUB ALREADY EXISTS - RESPOND YES TO PURGE OLD

   AND KEEP NEW PURGE OLD?YES *60*FCLOSE FAILURE (93)

   SECURITY VIOLATION (FSERR 93) 

This security violation occurred for the following reasons:

This prevents unauthorized changes to the original file in its original group (the PUB group in this case), however, it is possible to save the file in the group to which you are logged on.

Now try saving the file as REPORT, without the PUB qualifier:

   K REPORT.OTHERGRPReturn

REPORT has now been kept in your OTHERGRP group as a new file.

File security in other groups

Stricter security applies to any group that is not PUB or your home group.

Log back on to your PUB group. Get into the editor and try to text in the REPORT.OTHERGRP file. What happened? You should see the following on your screen:

   +-F-I-L-E---I-N-F-O-R-M-A-T-I-O-N---D-I-S-P-L-A-Y+ !  ERROR

   NUMBER: 93 RESIDUE: 0 !  !  BLOCK NUMBER: 0 NUMREC: 0 !

   +------------------------------------------------+ *23*FAILURE

   TO OPEN TEXT FILE (93) SECURITY VIOLATION (FSERR 93) /

If you are not the creator of the file (the username.accountname,groupname that the system recognizes as the creator of the file), the system informs you that you have attempted to violate a security provision.

You cannot read, copy, or edit and keep a file from a non-PUB group that is not your home group unless:

You learn how to release those security provisions in module 5, "Working with Files."

	NOTE: The computer recognizes the creator of a file as the user.account identity of the person who first created the file.

The concept of account security becomes a little clearer in the context of copying and deleting files. That is why the subject comes up again in module 5, "Working with Files."

Remember: if you have files that must be kept entirely secure, keep them in a group other than PUB.