By Default Windows2000 comes with the RADIUS services defined in the
services file as 1812 and 1813. If you don't explicitly define different
ports in the RadiusNT admin, it will listen on those. All legacy and
most common RADIUS clients (terminal servers) still use 1645/1646,
however. Therefore, if you don't match ports between client and
server, they will not be able to talk.
For more information about this list (including removal) go to: