IDS Forum

Re: chunk access

Posted By: Ravi T
Date: Thursday, 24 March 2005, at 11:36 a.m.

In Response To: Re: chunk access (Martin Fuerderer )

Informix by default grants select, insert, update, and delete privileges to a table once its created originally, at least with the versions I have worked with so far. I don't know if 10g has changed that.

So, keep in mind that unless you revoke all from the <table name> just any body can access that table.

Hope this helps.

Ravi.

"Martin Fuer...." <MARTINFU@de.ibm.com> wrote:
Hi,

this is one of the reasons you are using a database
and not accessing the data directly in files. Afterall
you have to get some kind of "service" from an expensive
database product - and this is one of them.

The database server processes are running as user informx,
therefore they have access to all the data, and that is correct,
because otherwise the whole thing would not work. And that's
why the chunks need to have "*rw-rw---- informix informix"
access rights and owner/group.

Which users can access the data via SQL is controlled by the
database server. There are SQL statements like GRANT, REVOKE
and even role-based privileges for all kinds of access levels (connect,
read, write, ...). And this is how you allow or restrict data access
when using a database server product.

The UNIX file "access rights - owner/group" concept with access
only for "informix" is to ensure that nobody else can access
the data by by-passing the database server, e.g. steal the data without
having data access permissions in/from the database server.

Hmm. If this explanation doesn't lift the fog, then I recommend one
of the more basic training classes for relational databases (preferrably
for IBM Informix Dynamic Server, e.g. "Database Administration", but
something more general might do just as well), or get yourself a text
book explaining the concepts of relational databases and SQL.

After that I guess you should then be fine with IBM Informix manuals
like "Guide to SQL: Tutorial", "Database Design and Implementation
Guide" and "Administrator's Guide". You can of course start with these
manuals right away (they are available for free download), but it may
not give you a structured approach to the fundamentals and hence not
necessarily a steep learning curve.

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich, Germany
Information Management

forum.subscriber@iiug.org wrote on 24.03.2005 06:05:50:

> Hi,
> The chunks are created with user and group informix. Theoritically only
users
> in this this group should be able to access the chunks. But i have
created a
> user "dummy" which is not in informix group. THis user is still able to
access the data in the database. How is this possible.
>
> I will list the steps here.
>
> All the chunks in the instance have the following permissions.
>
> crw-rw---- 1 informix informix 64 0x040004 Mar 1 16:29
/dev/vg04/rcalms2_dbs1
>
> And they are linked through links as
>
> lrwxrwxrwx 1 root sys 22 Mar 1 16:48
/dev/calms2/calms2_dbs1 -> /dev/vg04/rcalms2_dbs1
>
> created user dummy.
> created a database caldw and gave connect permission to dummy user on
this data
> base.
>
> And i tried to access the data in the database by giving
> select * from exp_cost.
> I was able to retrieve the data.
>
>
>
> My doubt is the "dummy" users does not have rw permision on this
character devices but still it is able to access. How is this?
>
>
>
> Bye.
>
>
>
>
>



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Messages In This Thread

• chunk access
  PARAMESHWAR PATHRI -- Thursday, 24 March 2005, at 12:05 a.m.
  • Re: chunk access
    Martin Fuerderer -- Thursday, 24 March 2005, at 2:48 a.m.
    • Re: chunk access
      Ravi T -- Thursday, 24 March 2005, at 11:36 a.m.
  • Re: chunk access
    Obnoxio The Chav -- Thursday, 24 March 2005, at 3:28 a.m.

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