Restricting access to functional database account through unix

Hi,

At present there is a functional database account which can be accessed when logging in through a unix server. At present it can be accessed through from any UNIX account on this server. Is there any way of restricting it so it can only be accessed through a functional unix account but only when logged directly onto this account. Not when scsu'ed to it?

Cheers
Paul

What DBMS are you using?

Oracle.

I had thought of a trigger restricting this but have an application which also uses the functional login to access the database and cant have that restricted.