Use a redhat enterprise machine as Remote Access server for Win2K network?

Hi all,

We need to replace our ageing Windows-based remote access server.
This machine currently has an Eicon DivaServer 4/8 port ISDN/PSTN RAS
card and uses the Windows Routing and Remote Access Service (RRAS) to
route the network traffic in from the Eicon card thru it's network
interface onto the rest of the LAN here. It uses RADIUS to
communicate the authentication details between the connecting client
and the Active Directory servers.

I'd like to use a RedHat machine to provide this functionality rather
than a Windows box and wondered if:

1) is this possible (sure it must be)
2) what software I need on the machine in order to achieve this?

The RADIUS on the RH Enterprise machine would be a client of the
RADIUS service provided by the primary Active Directory authentication
server, I guess routing would be handled by complex sets of 'route'
commands unless there's some Linux equivalent of Windows RRAS? If
anyone has such a scenario or can envisage how it would go together
I'd really appereciate hearing about it!

TIA,
Niall