which attribute identifies the client?

[Stefano Zanmarchi]

Hallo,
I can see in the logs the "client" calling my radius, e.g:

Wed Apr  1 13:28:06 2015 : Auth: Login OK: [jsmith at unipd.it] (from client
radius_garr_1 port 0 cli e4-d5-3d-b2-29-ca)
Wed Apr  1 13:28:07 2015 : Auth: Login OK: [anonymous at rug.nl] (from client
economia.unipd.it port 3 cli 94-eb-cd-6d-e0-ad)

which is the attribute containing the "client" (radius_garr_1,
economia.unipd.it,...)?
I'd like to use it in the %{...} form to perform some filtering in the
authorize section of inner-tunnel file.

Thanks a lot,
Stefano