WEBI - Identification of the WebI client workstation

Hi.

Environment context :
BO 4.1
Oracle 11g

We already have security policies enforced on the Oracle Database with customs VPD functions (Oracle Virtual Private Database).
To do so, we are using the @variables (BOUSER, DOCID, etc.) in the universes with the BEGIN_SQL parameter (calling context functionalities on Oracle).
So far, so good.

Related to internal security policies, we now try to identify the WEBI client workstation where the user is logged on. IP address is the best candidate, but something else identifying the workstation could also do the job.

We try @variables, environnements variables, everything that we can think of. But with no success so far.

Any ideas ?

Olivier