Conference noted::hackers_v1

Hmmm. The Set file/enter has some interesting uses. Like generating level
8 and above sub-directories with files in that people (not in the know)
cant get at ! Is there any way of checking if a set file/enter has been
done on a file ???

This reminds me of the trick of creating an SFD on Tops-10 named
"     !.SFD".  No monitor call can accept that SFD name as a
directory specification, except for the call that changes your
default directory.  So if you hide files in there, the only people
can access them are the ones that know the secret, and only after
writing their own program to connect to the directory (usually
done in DDT, of course).

One of the bad effects of using this is that BACKUP can't see the
files, so they don't get saved on tape every night, and if you don't
save them yourself, you lose big on head crashes.  Would this be
true of a typical BACKUP on VMS with the SET FILE/ENTER kludge?
				/AHM/THX

	No, V4 common system disks depend on SET FILE/ENTER to make them
work - I very much hope our system disk *has* been backed up for the last 
9 months !


Trevor

SET FILE/ENTER and SET FILE/REMOVE are documented in the V4 manuals.  
Sort of takes the fun out of it.

VMS BACKUP works by scanning the index file (in image mode, anyway) so 
it won't miss files that you can't access through directories.  One of 
the easiest ways to hide files on VMS is to rename a directory to 
something other than '.DIR;1'.

tom_p

One warning about "hiding" files:  Should the disk ever be run through
VERIFY, those files will disappear on you.

(Actually, they'll show up as lost files.)

For a more interesting hack, you can chain your directories into a loop.  The
easiest way is with SET FILE/ENTER.  (You used to be able to do this with
RENAME, as long as you went down at least two levels - i.e., the system
checked for an attempt to rename a directory into itself, but not into some
descendent; now it checks more thoroughly.)  Once you've done this, a
DIR [...] gets interesting....
								-- Jerry

re .-1
	If you hack somebody this way, he may be tempted to delete all those
	'duplicate' files.

re .1 (?)
	Another way to create directories with depth > 9 is by using rooted
	directories (this'll get you to 17 levels or so).

SET FILE/ENTER followed by a DELETE gives an interesting directory listing
(no such file)  More useful (if you have a gripe with with your SYS$MANAGER)
is creating a 12 bazillion block file and then $SET FILE/REMOVE on it.  The
disk is full, but everyone still has the "normal" amount in his directory

-Mike

re .7

Yeah, but the 12 bazillion blocks will show up in your disk quota.  

Dave C.

If you've got sufficient privs, you could:
	1. disable quota on the disk
	2. create the 12 bazillion block file with owner of [1,4]. 
	   Does anybody know if you can use [0,0]?  That would have
	   rather amusing side-effects down the road....
	3. re-enable quota on the disk

Now the blocks aren't charged to you and they don't show up in the DIskQuota
listing.

If a file _can_ be created with owner [0,0], the next time the quota info.
gets re-built, the default record ([0,0]) will now have a /PERMANENT quota of
12 bazillion blocks, as will any accounts created afterwards, IF the system
manager doesn't notice the [0,0] record.

Yeah, on Tops-10, [3,3] (the spooling area) is usually left 
write enabled (WOM).  You can fill up the system disk there
(since it usually has a big quota, if not infinite).

But if you close the file, you can't delete it later without privs
if you entered it with the default protection.  So, rather than
get tracked down by the file's author PPN, the wise person
doesn't take advantage of this.
				/AHM