dial up users authentication problem

[Mohsen A. Momeni]

Hi,

I have two group of users connected to internet through a firewall for
traffic control. Both should be authenticated by firewall through a
RADIUS server before connecting to internet and there are different
user policies for different users in firewall.

1) LAN users.
2) Dial-up users which are connected to a router, and are
authenticated by a RADIUS server (for logging in)
The problem is that I don't want a second authentication in firewall.
I want the users logged in, can be automatically authenticated by the
firewall. Firewall should somehow know their username to apply the
policies.
I think there should be a mapping from IP to username in RADIUS server.

Is this possible? If yes, please tell me how.